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Cycles code internals: add support for mesh voxel grid attributes.

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These are internally stored as a 3D image textures, but accessible like e.g.
UV coordinates though the attribute node and getattribute().

This is convenient for rendering e.g. smoke objects where data like density is
really a property of the mesh, and it avoids having to specify the smoke object
in a texture node, instead the material will work with any smoke domain.
This commit is contained in:
Brecht Van Lommel
2014-03-29 13:03:48 +01:00
parent 393216a6df
commit 27043b8e40
13 changed files with 258 additions and 117 deletions
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75
intern/cycles/kernel/geom/geom_volume.h Normal file
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/*
* Copyright 2011-2013 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
*/
/* Volume Primitive
*
* Volumes are just regions inside meshes with the mesh surface as boundaries.
* There isn't as much data to access as for surfaces, there is only a position
* to do lookups in 3D voxel or procedural textures.
*
* 3D voxel textures can be assigned as attributes per mesh, which means the
* same shader can be used for volume objects with different densities, etc. */
CCL_NAMESPACE_BEGIN
#ifdef __VOLUME__
/* Return position normalized to 0..1 in mesh bounds */
ccl_device float3 volume_normalized_position(KernelGlobals *kg, const ShaderData *sd, float3 P)
{
/* todo: optimize this so it's just a single matrix multiplication when
* possible (not motion blur), or perhaps even just translation + scale */
AttributeElement attr_elem;
int attr_offset = find_attribute(kg, sd, ATTR_STD_GENERATED_TRANSFORM, &attr_elem);
object_inverse_position_transform(kg, sd, &P);
if(attr_offset != ATTR_STD_NOT_FOUND) {
Transform tfm = primitive_attribute_matrix(kg, sd, attr_offset);
P = transform_point(&tfm, P);
}
return P;
}
ccl_device float volume_attribute_float(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int id, float *dx, float *dy)
{
float3 P = volume_normalized_position(kg, sd, sd->P);
float4 r = kernel_tex_image_interp_3d(id, P.x, P.y, P.z);
if(dx) *dx = 0.0f;
if(dx) *dy = 0.0f;
/* todo: support float textures to lower memory usage for single floats */
return average(float4_to_float3(r));
}
ccl_device float3 volume_attribute_float3(KernelGlobals *kg, const ShaderData *sd, AttributeElement elem, int id, float3 *dx, float3 *dy)
{
float3 P = volume_normalized_position(kg, sd, sd->P);
float4 r = kernel_tex_image_interp_3d(id, P.x, P.y, P.z);
if(dx) *dx = make_float3(0.0f, 0.0f, 0.0f);
if(dy) *dy = make_float3(0.0f, 0.0f, 0.0f);
return float4_to_float3(r);
}
#endif
CCL_NAMESPACE_END