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#pragma BLENDER_REQUIRE(volumetric_lib.glsl)
/* Based on Frosbite Unified Volumetric.
* https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */
/* Step 4 : Apply final integration on top of the scene color. */
uniform sampler2D inSceneDepth;
layout(local_size_x = 1, local_size_y = 1) in;
#ifdef TARGET_IMG_FLOAT
layout(binding = 0, rgba32f) uniform image2D target_img;
#else
layout(binding = 0, rgba16f) uniform image2D target_img;
#endif
void main()
{
ivec2 co = ivec2(gl_GlobalInvocationID.xy);
vec2 uvs = co / vec2(textureSize(inSceneDepth, 0));
float scene_depth = texture(inSceneDepth, uvs).r;
vec3 transmittance, scattering;
volumetric_resolve(uvs, scene_depth, transmittance, scattering);
/* Approximate volume alpha by using a monochromatic transmittance
* and adding it to the scene alpha. */
float alpha = dot(transmittance, vec3(1.0 / 3.0));
vec4 color0 = vec4(scattering, 1.0 - alpha);
vec4 color1 = vec4(transmittance, alpha);
vec4 color_in = imageLoad(target_img, co);
vec4 color_out = color0 + color1 * color_in;
imageStore(target_img, co, color_out);
}
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