Thomas Dinges
6b8bb26c45
Required by Metal backend for efficient shader compilation. EEVEE material resource binding permutations now controlled via CreateInfo and selected based on material options. Other existing CreateInfo's also modified to ensure explicitness for depth-writing mode. Other missing bindings also addressed to ensure full compliance with the Metal backend. Authored by Apple: Michael Parkin-White Ref T96261 Reviewed By: fclem Differential Revision: https://developer.blender.org/D16243
81 lines
2.6 KiB
GLSL
81 lines
2.6 KiB
GLSL
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#pragma BLENDER_REQUIRE(volumetric_lib.glsl)
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/* Based on Frosbite Unified Volumetric.
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* https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */
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/* Step 3 : Integrate for each froxel the final amount of light
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* scattered back to the viewer and the amount of transmittance. */
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/* Globals when using OPTI */
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#ifdef USE_VOLUME_OPTI
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vec3 finalScattering;
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vec3 finalTransmittance;
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#endif
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void main()
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{
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/* Start with full transmittance and no scattered light. */
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finalScattering = vec3(0.0);
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finalTransmittance = vec3(1.0);
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vec3 tex_size = vec3(textureSize(volumeScattering, 0).xyz);
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/* Compute view ray. */
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vec2 uvs = gl_FragCoord.xy / tex_size.xy;
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vec3 ndc_cell = volume_to_ndc(vec3(uvs, 1e-5));
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vec3 view_cell = get_view_space_from_depth(ndc_cell.xy, ndc_cell.z);
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/* Ortho */
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float prev_ray_len = view_cell.z;
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float orig_ray_len = 1.0;
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/* Persp */
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if (ProjectionMatrix[3][3] == 0.0) {
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prev_ray_len = length(view_cell);
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orig_ray_len = prev_ray_len / view_cell.z;
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}
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#ifdef USE_VOLUME_OPTI
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int slice = textureSize(volumeScattering, 0).z;
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ivec2 texco = ivec2(gl_FragCoord.xy);
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#else
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int slice = volumetric_geom_iface.slice;
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#endif
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for (int i = 0; i <= slice; i++) {
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ivec3 volume_cell = ivec3(ivec2(gl_FragCoord.xy), i);
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vec3 Lscat = texelFetch(volumeScattering, volume_cell, 0).rgb;
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vec3 s_extinction = texelFetch(volumeExtinction, volume_cell, 0).rgb;
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float cell_depth = volume_z_to_view_z((float(i) + 1.0) / tex_size.z);
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float ray_len = orig_ray_len * cell_depth;
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/* Emission does not work of there is no extinction because
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* Tr evaluates to 1.0 leading to Lscat = 0.0. (See T65771) */
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s_extinction = max(vec3(1e-7) * step(1e-5, Lscat), s_extinction);
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/* Evaluate Scattering */
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float s_len = abs(ray_len - prev_ray_len);
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prev_ray_len = ray_len;
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vec3 Tr = exp(-s_extinction * s_len);
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/* integrate along the current step segment */
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/* NOTE: Original calculation carries precision issues when compiling for AMD GPUs
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* and running Metal. This version of the equation retains precision well for all
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* macOS HW configurations. */
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Lscat = (Lscat * (1.0f - Tr)) / max(vec3(1e-8), s_extinction);
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/* accumulate and also take into account the transmittance from previous steps */
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finalScattering += finalTransmittance * Lscat;
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finalTransmittance *= Tr;
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#ifdef USE_VOLUME_OPTI
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ivec3 coord = ivec3(texco, i);
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imageStore(finalScattering_img, coord, vec4(finalScattering, 0.0));
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imageStore(finalTransmittance_img, coord, vec4(finalTransmittance, 0.0));
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#endif
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}
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}
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