blender/intern/cycles/kernel/kernel_globals.h
Brecht Van Lommel de9dffc61e Cycles: initial subsurface multiple scattering support. It's not working as
well as I would like, but it works, just add a subsurface scattering node and
you can use it like any other BSDF.

It is using fully raytraced sampling compatible with progressive rendering
and other more advanced rendering algorithms we might used in the future, and
it uses no extra memory so it's suitable for complex scenes.

Disadvantage is that it can be quite noisy and slow. Two limitations that will
be solved are that it does not work with bump mapping yet, and that the falloff
function used is a simple cubic function, it's not using the real BSSRDF
falloff function yet.

The node has a color input, along with a scattering radius for each RGB color
channel along with an overall scale factor for the radii.

There is also no GPU support yet, will test if I can get that working later.

Node Documentation:
http://wiki.blender.org/index.php/Doc:2.6/Manual/Render/Cycles/Nodes/Shaders#BSSRDF

Implementation notes:
http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/Subsurface_Scattering
2013-04-01 20:26:52 +00:00

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C

/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* Constant Globals */
CCL_NAMESPACE_BEGIN
/* On the CPU, we pass along the struct KernelGlobals to nearly everywhere in
* the kernel, to access constant data. These are all stored as "textures", but
* these are really just standard arrays. We can't use actually globals because
* multiple renders may be running inside the same process. */
#ifdef __KERNEL_CPU__
#ifdef __OSL__
struct OSLGlobals;
struct OSLThreadData;
struct OSLShadingSystem;
#endif
#define MAX_BYTE_IMAGES 512
#define MAX_FLOAT_IMAGES 5
typedef struct KernelGlobals {
texture_image_uchar4 texture_byte_images[MAX_BYTE_IMAGES];
texture_image_float4 texture_float_images[MAX_FLOAT_IMAGES];
#define KERNEL_TEX(type, ttype, name) ttype name;
#define KERNEL_IMAGE_TEX(type, ttype, name)
#include "kernel_textures.h"
KernelData __data;
#ifdef __OSL__
/* On the CPU, we also have the OSL globals here. Most data structures are shared
* with SVM, the difference is in the shaders and object/mesh attributes. */
OSLGlobals *osl;
OSLShadingSystem *osl_ss;
OSLThreadData *osl_tdata;
#endif
} KernelGlobals;
#endif
/* For CUDA, constant memory textures must be globals, so we can't put them
* into a struct. As a result we don't actually use this struct and use actual
* globals and simply pass along a NULL pointer everywhere, which we hope gets
* optimized out. */
#ifdef __KERNEL_CUDA__
__constant__ KernelData __data;
typedef struct KernelGlobals {} KernelGlobals;
#define KERNEL_TEX(type, ttype, name) ttype name;
#define KERNEL_IMAGE_TEX(type, ttype, name) ttype name;
#include "kernel_textures.h"
#endif
/* OpenCL */
#ifdef __KERNEL_OPENCL__
typedef struct KernelGlobals {
__constant KernelData *data;
#define KERNEL_TEX(type, ttype, name) \
__global type *name;
#include "kernel_textures.h"
} KernelGlobals;
#endif
/* Interpolated lookup table access */
__device float lookup_table_read(KernelGlobals *kg, float x, int offset, int size)
{
x = clamp(x, 0.0f, 1.0f)*(size-1);
int index = min((int)x, size-1);
int nindex = min(index+1, size-1);
float t = x - index;
float data0 = kernel_tex_fetch(__lookup_table, index + offset);
if(t == 0.0f)
return data0;
float data1 = kernel_tex_fetch(__lookup_table, nindex + offset);
return (1.0f - t)*data0 + t*data1;
}
__device float lookup_table_read_2D(KernelGlobals *kg, float x, float y, int offset, int xsize, int ysize)
{
y = clamp(y, 0.0f, 1.0f)*(ysize-1);
int index = min((int)y, ysize-1);
int nindex = min(index+1, ysize-1);
float t = y - index;
float data0 = lookup_table_read(kg, x, offset + xsize*index, xsize);
if(t == 0.0f)
return data0;
float data1 = lookup_table_read(kg, x, offset + xsize*nindex, xsize);
return (1.0f - t)*data0 + t*data1;
}
CCL_NAMESPACE_END