/*
 * Adapted from code Copyright 2009-2010 NVIDIA Corporation
 * Modifications Copyright 2011, Blender Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * "Persistent while-while kernel" used in:
 *
 * "Understanding the Efficiency of Ray Traversal on GPUs",
 * Timo Aila and Samuli Laine,
 * Proc. High-Performance Graphics 2009
 */

/* bottom-most stack entry, indicating the end of traversal */
#define ENTRYPOINT_SENTINEL 0x76543210

/* 64 object BVH + 64 mesh BVH + 64 object node splitting */
#define BVH_STACK_SIZE 192
#define BVH_NODE_SIZE 4
#define TRI_NODE_SIZE 3

/* silly workaround for float extended precision that happens when compiling
 * without sse support on x86, it results in different results for float ops
 * that you would otherwise expect to compare correctly */
#if !defined(__i386__) || defined(__SSE__)
#define NO_EXTENDED_PRECISION
#else
#define NO_EXTENDED_PRECISION volatile
#endif

#include "geom_object.h"
#include "geom_curve.h"
#include "geom_triangle.h"

CCL_NAMESPACE_BEGIN

/* BVH intersection function variations */

#define BVH_INSTANCING			1
#define BVH_MOTION				2
#define BVH_HAIR				4
#define BVH_HAIR_MINIMUM_WIDTH	8

#define BVH_FUNCTION_NAME bvh_intersect
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_traversal.h"

#if defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_traversal.h"
#endif

#if defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH
#include "geom_bvh_traversal.h"
#endif

#if defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_traversal.h"
#endif

#if defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_HAIR_MINIMUM_WIDTH|BVH_MOTION
#include "geom_bvh_traversal.h"
#endif

#if defined(__SUBSURFACE__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface
#define BVH_FUNCTION_FEATURES 0
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__INSTANCING__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_instancing
#define BVH_FUNCTION_FEATURES BVH_INSTANCING
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__HAIR__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_hair
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_MOTION
#include "geom_bvh_subsurface.h"
#endif

#if defined(__SUBSURFACE__) && defined(__HAIR__) && defined(__OBJECT_MOTION__)
#define BVH_FUNCTION_NAME bvh_intersect_subsurface_hair_motion
#define BVH_FUNCTION_FEATURES BVH_INSTANCING|BVH_HAIR|BVH_MOTION
#include "geom_bvh_subsurface.h"
#endif

/* to work around titan bug when using arrays instead of textures */
#if !defined(__KERNEL_CUDA__) || defined(__KERNEL_CUDA_TEX_STORAGE__)
ccl_device_inline
#else
ccl_device_noinline
#endif
#ifdef __HAIR__ 
bool scene_intersect(KernelGlobals *kg, const Ray *ray, const uint visibility, Intersection *isect, uint *lcg_state, float difl, float extmax)
#else
bool scene_intersect(KernelGlobals *kg, const Ray *ray, const uint visibility, Intersection *isect)
#endif
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_hair_motion(kg, ray, isect, visibility, lcg_state, difl, extmax);
#endif /* __HAIR__ */

		return bvh_intersect_motion(kg, ray, isect, visibility);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__ 
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_hair(kg, ray, isect, visibility, lcg_state, difl, extmax);
#endif /* __HAIR__ */

#ifdef __KERNEL_CPU__

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_instancing(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

	return bvh_intersect(kg, ray, isect, visibility);
#else /* __KERNEL_CPU__ */

#ifdef __INSTANCING__
	return bvh_intersect_instancing(kg, ray, isect, visibility);
#else
	return bvh_intersect(kg, ray, isect, visibility);
#endif /* __INSTANCING__ */

#endif /* __KERNEL_CPU__ */
}

/* to work around titan bug when using arrays instead of textures */
#ifdef __SUBSURFACE__
#if !defined(__KERNEL_CUDA__) || defined(__KERNEL_CUDA_TEX_STORAGE__)
ccl_device_inline
#else
ccl_device_noinline
#endif
uint scene_intersect_subsurface(KernelGlobals *kg, const Ray *ray, Intersection *isect, int subsurface_object, uint *lcg_state, int max_hits)
{
#ifdef __OBJECT_MOTION__
	if(kernel_data.bvh.have_motion) {
#ifdef __HAIR__
		if(kernel_data.bvh.have_curves)
			return bvh_intersect_subsurface_hair_motion(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#endif /* __HAIR__ */

		return bvh_intersect_subsurface_motion(kg, ray, isect, subsurface_object, lcg_state, max_hits);
	}
#endif /* __OBJECT_MOTION__ */

#ifdef __HAIR__ 
	if(kernel_data.bvh.have_curves)
		return bvh_intersect_subsurface_hair(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#endif /* __HAIR__ */

#ifdef __KERNEL_CPU__

#ifdef __INSTANCING__
	if(kernel_data.bvh.have_instancing)
		return bvh_intersect_subsurface_instancing(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#endif /* __INSTANCING__ */

	return bvh_intersect_subsurface(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#else /* __KERNEL_CPU__ */

#ifdef __INSTANCING__
	return bvh_intersect_subsurface_instancing(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#else
	return bvh_intersect_subsurface(kg, ray, isect, subsurface_object, lcg_state, max_hits);
#endif /* __INSTANCING__ */

#endif /* __KERNEL_CPU__ */
}
#endif

/* Ray offset to avoid self intersection */

ccl_device_inline float3 ray_offset(float3 P, float3 Ng)
{
#ifdef __INTERSECTION_REFINE__
	const float epsilon_f = 1e-5f;
	/* ideally this should match epsilon_f, but instancing and motion blur
	 * precision makes it problematic */
	const float epsilon_test = 1.0f;
	const int epsilon_i = 32;

	float3 res;

	/* x component */
	if(fabsf(P.x) < epsilon_test) {
		res.x = P.x + Ng.x*epsilon_f;
	}
	else {
		uint ix = __float_as_uint(P.x);
		ix += ((ix ^ __float_as_uint(Ng.x)) >> 31)? -epsilon_i: epsilon_i;
		res.x = __uint_as_float(ix);
	}

	/* y component */
	if(fabsf(P.y) < epsilon_test) {
		res.y = P.y + Ng.y*epsilon_f;
	}
	else {
		uint iy = __float_as_uint(P.y);
		iy += ((iy ^ __float_as_uint(Ng.y)) >> 31)? -epsilon_i: epsilon_i;
		res.y = __uint_as_float(iy);
	}

	/* z component */
	if(fabsf(P.z) < epsilon_test) {
		res.z = P.z + Ng.z*epsilon_f;
	}
	else {
		uint iz = __float_as_uint(P.z);
		iz += ((iz ^ __float_as_uint(Ng.z)) >> 31)? -epsilon_i: epsilon_i;
		res.z = __uint_as_float(iz);
	}

	return res;
#else
	const float epsilon_f = 1e-4f;
	return P + epsilon_f*Ng;
#endif
}

CCL_NAMESPACE_END