forked from bartvdbraak/blender
876 lines
18 KiB
C++
876 lines
18 KiB
C++
/*
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* Copyright 2011-2013 Blender Foundation
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __UTIL_MATH_H__
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#define __UTIL_MATH_H__
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/* Math
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*
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* Basic math functions on scalar and vector types. This header is used by
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* both the kernel code when compiled as C++, and other C++ non-kernel code. */
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#ifndef __KERNEL_GPU__
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# include <cmath>
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#endif
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#ifdef __HIP__
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# include <hip/hip_vector_types.h>
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#endif
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#include <float.h>
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#include <math.h>
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#include <stdio.h>
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#include "util/types.h"
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CCL_NAMESPACE_BEGIN
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/* Float Pi variations */
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/* Division */
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#ifndef M_PI_F
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# define M_PI_F (3.1415926535897932f) /* pi */
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#endif
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#ifndef M_PI_2_F
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# define M_PI_2_F (1.5707963267948966f) /* pi/2 */
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#endif
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#ifndef M_PI_4_F
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# define M_PI_4_F (0.7853981633974830f) /* pi/4 */
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#endif
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#ifndef M_1_PI_F
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# define M_1_PI_F (0.3183098861837067f) /* 1/pi */
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#endif
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#ifndef M_2_PI_F
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# define M_2_PI_F (0.6366197723675813f) /* 2/pi */
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#endif
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#ifndef M_1_2PI_F
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# define M_1_2PI_F (0.1591549430918953f) /* 1/(2*pi) */
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#endif
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#ifndef M_SQRT_PI_8_F
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# define M_SQRT_PI_8_F (0.6266570686577501f) /* sqrt(pi/8) */
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#endif
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#ifndef M_LN_2PI_F
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# define M_LN_2PI_F (1.8378770664093454f) /* ln(2*pi) */
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#endif
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/* Multiplication */
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#ifndef M_2PI_F
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# define M_2PI_F (6.2831853071795864f) /* 2*pi */
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#endif
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#ifndef M_4PI_F
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# define M_4PI_F (12.566370614359172f) /* 4*pi */
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#endif
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/* Float sqrt variations */
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#ifndef M_SQRT2_F
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# define M_SQRT2_F (1.4142135623730950f) /* sqrt(2) */
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#endif
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#ifndef M_LN2_F
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# define M_LN2_F (0.6931471805599453f) /* ln(2) */
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#endif
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#ifndef M_LN10_F
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# define M_LN10_F (2.3025850929940457f) /* ln(10) */
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#endif
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/* Scalar */
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#ifndef __HIP__
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# ifdef _WIN32
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ccl_device_inline float fmaxf(float a, float b)
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{
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return (a > b) ? a : b;
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}
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ccl_device_inline float fminf(float a, float b)
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{
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return (a < b) ? a : b;
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}
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# endif /* _WIN32 */
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#endif /* __HIP__ */
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#ifndef __KERNEL_GPU__
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using std::isfinite;
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using std::isnan;
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using std::sqrt;
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ccl_device_inline int abs(int x)
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{
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return (x > 0) ? x : -x;
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}
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ccl_device_inline int max(int a, int b)
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{
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return (a > b) ? a : b;
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}
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ccl_device_inline int min(int a, int b)
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{
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return (a < b) ? a : b;
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}
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ccl_device_inline uint min(uint a, uint b)
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{
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return (a < b) ? a : b;
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}
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ccl_device_inline float max(float a, float b)
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{
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return (a > b) ? a : b;
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}
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ccl_device_inline float min(float a, float b)
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{
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return (a < b) ? a : b;
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}
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ccl_device_inline double max(double a, double b)
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{
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return (a > b) ? a : b;
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}
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ccl_device_inline double min(double a, double b)
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{
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return (a < b) ? a : b;
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}
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/* These 2 guys are templated for usage with registers data.
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*
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* NOTE: Since this is CPU-only functions it is ok to use references here.
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* But for other devices we'll need to be careful about this.
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*/
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template<typename T> ccl_device_inline T min4(const T &a, const T &b, const T &c, const T &d)
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{
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return min(min(a, b), min(c, d));
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}
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template<typename T> ccl_device_inline T max4(const T &a, const T &b, const T &c, const T &d)
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{
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return max(max(a, b), max(c, d));
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}
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#endif /* __KERNEL_GPU__ */
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ccl_device_inline float min4(float a, float b, float c, float d)
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{
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return min(min(a, b), min(c, d));
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}
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ccl_device_inline float max4(float a, float b, float c, float d)
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{
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return max(max(a, b), max(c, d));
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}
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/* Int/Float conversion */
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ccl_device_inline int as_int(uint i)
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{
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union {
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uint ui;
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int i;
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} u;
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u.ui = i;
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return u.i;
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}
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ccl_device_inline uint as_uint(int i)
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{
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union {
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uint ui;
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int i;
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} u;
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u.i = i;
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return u.ui;
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}
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ccl_device_inline uint as_uint(float f)
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{
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union {
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uint i;
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float f;
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} u;
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u.f = f;
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return u.i;
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}
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#ifndef __HIP__
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ccl_device_inline int __float_as_int(float f)
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{
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union {
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int i;
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float f;
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} u;
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u.f = f;
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return u.i;
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}
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ccl_device_inline float __int_as_float(int i)
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{
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union {
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int i;
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float f;
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} u;
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u.i = i;
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return u.f;
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}
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ccl_device_inline uint __float_as_uint(float f)
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{
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union {
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uint i;
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float f;
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} u;
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u.f = f;
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return u.i;
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}
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ccl_device_inline float __uint_as_float(uint i)
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{
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union {
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uint i;
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float f;
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} u;
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u.i = i;
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return u.f;
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}
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#endif
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ccl_device_inline int4 __float4_as_int4(float4 f)
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{
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#ifdef __KERNEL_SSE__
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return int4(_mm_castps_si128(f.m128));
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#else
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return make_int4(
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__float_as_int(f.x), __float_as_int(f.y), __float_as_int(f.z), __float_as_int(f.w));
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#endif
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}
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ccl_device_inline float4 __int4_as_float4(int4 i)
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{
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#ifdef __KERNEL_SSE__
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return float4(_mm_castsi128_ps(i.m128));
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#else
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return make_float4(
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__int_as_float(i.x), __int_as_float(i.y), __int_as_float(i.z), __int_as_float(i.w));
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#endif
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}
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template<typename T> ccl_device_inline uint pointer_pack_to_uint_0(T *ptr)
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{
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return ((uint64_t)ptr) & 0xFFFFFFFF;
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}
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template<typename T> ccl_device_inline uint pointer_pack_to_uint_1(T *ptr)
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{
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return (((uint64_t)ptr) >> 32) & 0xFFFFFFFF;
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}
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template<typename T> ccl_device_inline T *pointer_unpack_from_uint(const uint a, const uint b)
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{
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return (T *)(((uint64_t)b << 32) | a);
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}
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ccl_device_inline uint uint16_pack_to_uint(const uint a, const uint b)
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{
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return (a << 16) | b;
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}
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ccl_device_inline uint uint16_unpack_from_uint_0(const uint i)
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{
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return i >> 16;
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}
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ccl_device_inline uint uint16_unpack_from_uint_1(const uint i)
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{
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return i & 0xFFFF;
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}
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/* Versions of functions which are safe for fast math. */
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ccl_device_inline bool isnan_safe(float f)
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{
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unsigned int x = __float_as_uint(f);
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return (x << 1) > 0xff000000u;
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}
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ccl_device_inline bool isfinite_safe(float f)
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{
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/* By IEEE 754 rule, 2*Inf equals Inf */
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unsigned int x = __float_as_uint(f);
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return (f == f) && (x == 0 || x == (1u << 31) || (f != 2.0f * f)) && !((x << 1) > 0xff000000u);
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}
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ccl_device_inline float ensure_finite(float v)
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{
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return isfinite_safe(v) ? v : 0.0f;
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}
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ccl_device_inline int clamp(int a, int mn, int mx)
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{
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return min(max(a, mn), mx);
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}
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ccl_device_inline float clamp(float a, float mn, float mx)
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{
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return min(max(a, mn), mx);
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}
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ccl_device_inline float mix(float a, float b, float t)
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{
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return a + t * (b - a);
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}
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ccl_device_inline float smoothstep(float edge0, float edge1, float x)
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{
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float result;
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if (x < edge0)
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result = 0.0f;
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else if (x >= edge1)
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result = 1.0f;
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else {
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float t = (x - edge0) / (edge1 - edge0);
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result = (3.0f - 2.0f * t) * (t * t);
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}
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return result;
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}
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#ifndef __KERNEL_CUDA__
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ccl_device_inline float saturatef(float a)
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{
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return clamp(a, 0.0f, 1.0f);
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}
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#else
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ccl_device_inline float saturatef(float a)
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{
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return __saturatef(a);
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}
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#endif /* __KERNEL_CUDA__ */
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ccl_device_inline int float_to_int(float f)
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{
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return (int)f;
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}
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ccl_device_inline int floor_to_int(float f)
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{
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return float_to_int(floorf(f));
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}
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ccl_device_inline int quick_floor_to_int(float x)
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{
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return float_to_int(x) - ((x < 0) ? 1 : 0);
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}
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ccl_device_inline float floorfrac(float x, ccl_private int *i)
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{
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*i = quick_floor_to_int(x);
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return x - *i;
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}
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ccl_device_inline int ceil_to_int(float f)
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{
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return float_to_int(ceilf(f));
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}
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ccl_device_inline float fractf(float x)
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{
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return x - floorf(x);
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}
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/* Adapted from godot-engine math_funcs.h. */
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ccl_device_inline float wrapf(float value, float max, float min)
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{
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float range = max - min;
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return (range != 0.0f) ? value - (range * floorf((value - min) / range)) : min;
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}
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ccl_device_inline float pingpongf(float a, float b)
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{
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return (b != 0.0f) ? fabsf(fractf((a - b) / (b * 2.0f)) * b * 2.0f - b) : 0.0f;
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}
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ccl_device_inline float smoothminf(float a, float b, float k)
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{
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if (k != 0.0f) {
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float h = fmaxf(k - fabsf(a - b), 0.0f) / k;
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return fminf(a, b) - h * h * h * k * (1.0f / 6.0f);
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}
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else {
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return fminf(a, b);
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}
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}
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ccl_device_inline float signf(float f)
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{
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return (f < 0.0f) ? -1.0f : 1.0f;
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}
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ccl_device_inline float nonzerof(float f, float eps)
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{
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if (fabsf(f) < eps)
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return signf(f) * eps;
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else
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return f;
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}
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/* `signum` function testing for zero. Matches GLSL and OSL functions. */
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ccl_device_inline float compatible_signf(float f)
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{
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if (f == 0.0f) {
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return 0.0f;
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}
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else {
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return signf(f);
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}
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}
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ccl_device_inline float smoothstepf(float f)
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{
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float ff = f * f;
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return (3.0f * ff - 2.0f * ff * f);
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}
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ccl_device_inline int mod(int x, int m)
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{
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return (x % m + m) % m;
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}
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ccl_device_inline float3 float2_to_float3(const float2 a)
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{
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return make_float3(a.x, a.y, 0.0f);
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}
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ccl_device_inline float3 float4_to_float3(const float4 a)
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{
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return make_float3(a.x, a.y, a.z);
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}
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ccl_device_inline float4 float3_to_float4(const float3 a)
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{
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return make_float4(a.x, a.y, a.z, 1.0f);
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}
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ccl_device_inline float inverse_lerp(float a, float b, float x)
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{
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return (x - a) / (b - a);
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}
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/* Cubic interpolation between b and c, a and d are the previous and next point. */
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ccl_device_inline float cubic_interp(float a, float b, float c, float d, float x)
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{
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return 0.5f *
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(((d + 3.0f * (b - c) - a) * x + (2.0f * a - 5.0f * b + 4.0f * c - d)) * x +
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(c - a)) *
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x +
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b;
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}
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CCL_NAMESPACE_END
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#include "util/math_int2.h"
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#include "util/math_int3.h"
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#include "util/math_int4.h"
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#include "util/math_float2.h"
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#include "util/math_float3.h"
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#include "util/math_float4.h"
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#include "util/rect.h"
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CCL_NAMESPACE_BEGIN
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/* Interpolation */
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template<class A, class B> A lerp(const A &a, const A &b, const B &t)
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{
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return (A)(a * ((B)1 - t) + b * t);
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}
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/* Triangle */
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ccl_device_inline float triangle_area(ccl_private const float3 &v1,
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ccl_private const float3 &v2,
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ccl_private const float3 &v3)
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{
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return len(cross(v3 - v2, v1 - v2)) * 0.5f;
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}
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/* Orthonormal vectors */
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ccl_device_inline void make_orthonormals(const float3 N,
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ccl_private float3 *a,
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ccl_private float3 *b)
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{
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#if 0
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if (fabsf(N.y) >= 0.999f) {
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*a = make_float3(1, 0, 0);
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*b = make_float3(0, 0, 1);
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return;
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}
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if (fabsf(N.z) >= 0.999f) {
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*a = make_float3(1, 0, 0);
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*b = make_float3(0, 1, 0);
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return;
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}
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#endif
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if (N.x != N.y || N.x != N.z)
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*a = make_float3(N.z - N.y, N.x - N.z, N.y - N.x); //(1,1,1)x N
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else
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*a = make_float3(N.z - N.y, N.x + N.z, -N.y - N.x); //(-1,1,1)x N
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*a = normalize(*a);
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*b = cross(N, *a);
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}
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/* Color division */
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ccl_device_inline float3 safe_invert_color(float3 a)
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{
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float x, y, z;
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x = (a.x != 0.0f) ? 1.0f / a.x : 0.0f;
|
|
y = (a.y != 0.0f) ? 1.0f / a.y : 0.0f;
|
|
z = (a.z != 0.0f) ? 1.0f / a.z : 0.0f;
|
|
|
|
return make_float3(x, y, z);
|
|
}
|
|
|
|
ccl_device_inline float3 safe_divide_color(float3 a, float3 b)
|
|
{
|
|
float x, y, z;
|
|
|
|
x = (b.x != 0.0f) ? a.x / b.x : 0.0f;
|
|
y = (b.y != 0.0f) ? a.y / b.y : 0.0f;
|
|
z = (b.z != 0.0f) ? a.z / b.z : 0.0f;
|
|
|
|
return make_float3(x, y, z);
|
|
}
|
|
|
|
ccl_device_inline float3 safe_divide_even_color(float3 a, float3 b)
|
|
{
|
|
float x, y, z;
|
|
|
|
x = (b.x != 0.0f) ? a.x / b.x : 0.0f;
|
|
y = (b.y != 0.0f) ? a.y / b.y : 0.0f;
|
|
z = (b.z != 0.0f) ? a.z / b.z : 0.0f;
|
|
|
|
/* try to get gray even if b is zero */
|
|
if (b.x == 0.0f) {
|
|
if (b.y == 0.0f) {
|
|
x = z;
|
|
y = z;
|
|
}
|
|
else if (b.z == 0.0f) {
|
|
x = y;
|
|
z = y;
|
|
}
|
|
else
|
|
x = 0.5f * (y + z);
|
|
}
|
|
else if (b.y == 0.0f) {
|
|
if (b.z == 0.0f) {
|
|
y = x;
|
|
z = x;
|
|
}
|
|
else
|
|
y = 0.5f * (x + z);
|
|
}
|
|
else if (b.z == 0.0f) {
|
|
z = 0.5f * (x + y);
|
|
}
|
|
|
|
return make_float3(x, y, z);
|
|
}
|
|
|
|
/* Rotation of point around axis and angle */
|
|
|
|
ccl_device_inline float3 rotate_around_axis(float3 p, float3 axis, float angle)
|
|
{
|
|
float costheta = cosf(angle);
|
|
float sintheta = sinf(angle);
|
|
float3 r;
|
|
|
|
r.x = ((costheta + (1 - costheta) * axis.x * axis.x) * p.x) +
|
|
(((1 - costheta) * axis.x * axis.y - axis.z * sintheta) * p.y) +
|
|
(((1 - costheta) * axis.x * axis.z + axis.y * sintheta) * p.z);
|
|
|
|
r.y = (((1 - costheta) * axis.x * axis.y + axis.z * sintheta) * p.x) +
|
|
((costheta + (1 - costheta) * axis.y * axis.y) * p.y) +
|
|
(((1 - costheta) * axis.y * axis.z - axis.x * sintheta) * p.z);
|
|
|
|
r.z = (((1 - costheta) * axis.x * axis.z - axis.y * sintheta) * p.x) +
|
|
(((1 - costheta) * axis.y * axis.z + axis.x * sintheta) * p.y) +
|
|
((costheta + (1 - costheta) * axis.z * axis.z) * p.z);
|
|
|
|
return r;
|
|
}
|
|
|
|
/* NaN-safe math ops */
|
|
|
|
ccl_device_inline float safe_sqrtf(float f)
|
|
{
|
|
return sqrtf(max(f, 0.0f));
|
|
}
|
|
|
|
ccl_device_inline float inversesqrtf(float f)
|
|
{
|
|
return (f > 0.0f) ? 1.0f / sqrtf(f) : 0.0f;
|
|
}
|
|
|
|
ccl_device float safe_asinf(float a)
|
|
{
|
|
return asinf(clamp(a, -1.0f, 1.0f));
|
|
}
|
|
|
|
ccl_device float safe_acosf(float a)
|
|
{
|
|
return acosf(clamp(a, -1.0f, 1.0f));
|
|
}
|
|
|
|
ccl_device float compatible_powf(float x, float y)
|
|
{
|
|
#ifdef __KERNEL_GPU__
|
|
if (y == 0.0f) /* x^0 -> 1, including 0^0 */
|
|
return 1.0f;
|
|
|
|
/* GPU pow doesn't accept negative x, do manual checks here */
|
|
if (x < 0.0f) {
|
|
if (fmodf(-y, 2.0f) == 0.0f)
|
|
return powf(-x, y);
|
|
else
|
|
return -powf(-x, y);
|
|
}
|
|
else if (x == 0.0f)
|
|
return 0.0f;
|
|
#endif
|
|
return powf(x, y);
|
|
}
|
|
|
|
ccl_device float safe_powf(float a, float b)
|
|
{
|
|
if (UNLIKELY(a < 0.0f && b != float_to_int(b)))
|
|
return 0.0f;
|
|
|
|
return compatible_powf(a, b);
|
|
}
|
|
|
|
ccl_device float safe_divide(float a, float b)
|
|
{
|
|
return (b != 0.0f) ? a / b : 0.0f;
|
|
}
|
|
|
|
ccl_device float safe_logf(float a, float b)
|
|
{
|
|
if (UNLIKELY(a <= 0.0f || b <= 0.0f))
|
|
return 0.0f;
|
|
|
|
return safe_divide(logf(a), logf(b));
|
|
}
|
|
|
|
ccl_device float safe_modulo(float a, float b)
|
|
{
|
|
return (b != 0.0f) ? fmodf(a, b) : 0.0f;
|
|
}
|
|
|
|
ccl_device_inline float sqr(float a)
|
|
{
|
|
return a * a;
|
|
}
|
|
|
|
ccl_device_inline float pow20(float a)
|
|
{
|
|
return sqr(sqr(sqr(sqr(a)) * a));
|
|
}
|
|
|
|
ccl_device_inline float pow22(float a)
|
|
{
|
|
return sqr(a * sqr(sqr(sqr(a)) * a));
|
|
}
|
|
|
|
ccl_device_inline float beta(float x, float y)
|
|
{
|
|
return expf(lgammaf(x) + lgammaf(y) - lgammaf(x + y));
|
|
}
|
|
|
|
ccl_device_inline float xor_signmask(float x, int y)
|
|
{
|
|
return __int_as_float(__float_as_int(x) ^ y);
|
|
}
|
|
|
|
ccl_device float bits_to_01(uint bits)
|
|
{
|
|
return bits * (1.0f / (float)0xFFFFFFFF);
|
|
}
|
|
|
|
ccl_device_inline uint count_leading_zeros(uint x)
|
|
{
|
|
#if defined(__KERNEL_CUDA__) || defined(__KERNEL_OPTIX__) || defined(__KERNEL_HIP__)
|
|
return __clz(x);
|
|
#else
|
|
assert(x != 0);
|
|
# ifdef _MSC_VER
|
|
unsigned long leading_zero = 0;
|
|
_BitScanReverse(&leading_zero, x);
|
|
return (31 - leading_zero);
|
|
# else
|
|
return __builtin_clz(x);
|
|
# endif
|
|
#endif
|
|
}
|
|
|
|
ccl_device_inline uint count_trailing_zeros(uint x)
|
|
{
|
|
#if defined(__KERNEL_CUDA__) || defined(__KERNEL_OPTIX__) || defined(__KERNEL_HIP__)
|
|
return (__ffs(x) - 1);
|
|
#else
|
|
assert(x != 0);
|
|
# ifdef _MSC_VER
|
|
unsigned long ctz = 0;
|
|
_BitScanForward(&ctz, x);
|
|
return ctz;
|
|
# else
|
|
return __builtin_ctz(x);
|
|
# endif
|
|
#endif
|
|
}
|
|
|
|
ccl_device_inline uint find_first_set(uint x)
|
|
{
|
|
#if defined(__KERNEL_CUDA__) || defined(__KERNEL_OPTIX__) || defined(__KERNEL_HIP__)
|
|
return __ffs(x);
|
|
#else
|
|
# ifdef _MSC_VER
|
|
return (x != 0) ? (32 - count_leading_zeros(x & (-x))) : 0;
|
|
# else
|
|
return __builtin_ffs(x);
|
|
# endif
|
|
#endif
|
|
}
|
|
|
|
/* projections */
|
|
ccl_device_inline float2 map_to_tube(const float3 co)
|
|
{
|
|
float len, u, v;
|
|
len = sqrtf(co.x * co.x + co.y * co.y);
|
|
if (len > 0.0f) {
|
|
u = (1.0f - (atan2f(co.x / len, co.y / len) / M_PI_F)) * 0.5f;
|
|
v = (co.z + 1.0f) * 0.5f;
|
|
}
|
|
else {
|
|
u = v = 0.0f;
|
|
}
|
|
return make_float2(u, v);
|
|
}
|
|
|
|
ccl_device_inline float2 map_to_sphere(const float3 co)
|
|
{
|
|
float l = len(co);
|
|
float u, v;
|
|
if (l > 0.0f) {
|
|
if (UNLIKELY(co.x == 0.0f && co.y == 0.0f)) {
|
|
u = 0.0f; /* Otherwise domain error. */
|
|
}
|
|
else {
|
|
u = (1.0f - atan2f(co.x, co.y) / M_PI_F) / 2.0f;
|
|
}
|
|
v = 1.0f - safe_acosf(co.z / l) / M_PI_F;
|
|
}
|
|
else {
|
|
u = v = 0.0f;
|
|
}
|
|
return make_float2(u, v);
|
|
}
|
|
|
|
/* Compares two floats.
|
|
* Returns true if their absolute difference is smaller than abs_diff (for numbers near zero)
|
|
* or their relative difference is less than ulp_diff ULPs.
|
|
* Based on
|
|
* https://randomascii.wordpress.com/2012/02/25/comparing-floating-point-numbers-2012-edition/
|
|
*/
|
|
|
|
ccl_device_inline bool compare_floats(float a, float b, float abs_diff, int ulp_diff)
|
|
{
|
|
if (fabsf(a - b) < abs_diff) {
|
|
return true;
|
|
}
|
|
|
|
if ((a < 0.0f) != (b < 0.0f)) {
|
|
return false;
|
|
}
|
|
|
|
return (abs(__float_as_int(a) - __float_as_int(b)) < ulp_diff);
|
|
}
|
|
|
|
/* Calculate the angle between the two vectors a and b.
|
|
* The usual approach `acos(dot(a, b))` has severe precision issues for small angles,
|
|
* which are avoided by this method.
|
|
* Based on "Mangled Angles" from https://people.eecs.berkeley.edu/~wkahan/Mindless.pdf
|
|
*/
|
|
ccl_device_inline float precise_angle(float3 a, float3 b)
|
|
{
|
|
return 2.0f * atan2f(len(a - b), len(a + b));
|
|
}
|
|
|
|
/* Return value which is greater than the given one and is a power of two. */
|
|
ccl_device_inline uint next_power_of_two(uint x)
|
|
{
|
|
return x == 0 ? 1 : 1 << (32 - count_leading_zeros(x));
|
|
}
|
|
|
|
/* Return value which is lower than the given one and is a power of two. */
|
|
ccl_device_inline uint prev_power_of_two(uint x)
|
|
{
|
|
return x < 2 ? x : 1 << (31 - count_leading_zeros(x - 1));
|
|
}
|
|
|
|
#ifndef __has_builtin
|
|
# define __has_builtin(v) 0
|
|
#endif
|
|
|
|
/* Reverses the bits of a 32 bit integer. */
|
|
ccl_device_inline uint32_t reverse_integer_bits(uint32_t x)
|
|
{
|
|
/* Use a native instruction if it exists. */
|
|
#if defined(__arm__) || defined(__aarch64__)
|
|
__asm__("rbit %w0, %w1" : "=r"(x) : "r"(x));
|
|
return x;
|
|
#elif defined(__KERNEL_CUDA__)
|
|
return __brev(x);
|
|
#elif __has_builtin(__builtin_bitreverse32)
|
|
return __builtin_bitreverse32(x);
|
|
#else
|
|
/* Flip pairwise. */
|
|
x = ((x & 0x55555555) << 1) | ((x & 0xAAAAAAAA) >> 1);
|
|
/* Flip pairs. */
|
|
x = ((x & 0x33333333) << 2) | ((x & 0xCCCCCCCC) >> 2);
|
|
/* Flip nibbles. */
|
|
x = ((x & 0x0F0F0F0F) << 4) | ((x & 0xF0F0F0F0) >> 4);
|
|
/* Flip bytes. CPUs have an instruction for that, pretty fast one. */
|
|
# ifdef _MSC_VER
|
|
return _byteswap_ulong(x);
|
|
# elif defined(__INTEL_COMPILER)
|
|
return (uint32_t)_bswap((int)x);
|
|
# else
|
|
/* Assuming gcc or clang. */
|
|
return __builtin_bswap32(x);
|
|
# endif
|
|
#endif
|
|
}
|
|
|
|
CCL_NAMESPACE_END
|
|
|
|
#endif /* __UTIL_MATH_H__ */
|