Differential D5740 Diff 18034 source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl

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source/blender/draw/engines/eevee/shaders/volumetric_integration_frag.glsl


	/* Based on Frosbite Unified Volumetric.			/* Based on Frosbite Unified Volumetric.
	* https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */			* https://www.ea.com/frostbite/news/physically-based-unified-volumetric-rendering-in-frostbite */

	/* Step 3 : Integrate for each froxel the final amount of light			/* Step 3 : Integrate for each froxel the final amount of light
	* scattered back to the viewer and the amount of transmittance. */			* scattered back to the viewer and the amount of transmittance. */

	uniform sampler3D volumeScattering; /* Result of the scatter step */			uniform sampler3D volumeScattering; /* Result of the scatter step */
	uniform sampler3D volumeExtinction;			uniform sampler3D volumeExtinction;

				#ifdef USE_VOLUME_OPTI
				uniform layout(binding = 0, r11f_g11f_b10f) writeonly restrict image3D finalScattering_img;
				uniform layout(binding = 1, r11f_g11f_b10f) writeonly restrict image3D finalTransmittance_img;
				vec3 finalScattering;
				vec3 finalTransmittance;
				#else
	flat in int slice;			flat in int slice;

	layout(location = 0) out vec3 finalScattering;			layout(location = 0) out vec3 finalScattering;
	layout(location = 1) out vec3 finalTransmittance;			layout(location = 1) out vec3 finalTransmittance;
				#endif

	void main()			void main()
	{			{
	/* Start with full transmittance and no scattered light. */			/* Start with full transmittance and no scattered light. */
	finalScattering = vec3(0.0);			finalScattering = vec3(0.0);
	finalTransmittance = vec3(1.0);			finalTransmittance = vec3(1.0);

	vec3 tex_size = vec3(textureSize(volumeScattering, 0).xyz);			vec3 tex_size = vec3(textureSize(volumeScattering, 0).xyz);

	/* Compute view ray. */			/* Compute view ray. */
	vec2 uvs = gl_FragCoord.xy / tex_size.xy;			vec2 uvs = gl_FragCoord.xy / tex_size.xy;
	vec3 ndc_cell = volume_to_ndc(vec3(uvs, 1e-5));			vec3 ndc_cell = volume_to_ndc(vec3(uvs, 1e-5));
	vec3 view_cell = get_view_space_from_depth(ndc_cell.xy, ndc_cell.z);			vec3 view_cell = get_view_space_from_depth(ndc_cell.xy, ndc_cell.z);

	/* Ortho */			/* Ortho */
	float prev_ray_len = view_cell.z;			float prev_ray_len = view_cell.z;
	float orig_ray_len = 1.0;			float orig_ray_len = 1.0;

	/* Persp */			/* Persp */
	if (ProjectionMatrix[3][3] == 0.0) {			if (ProjectionMatrix[3][3] == 0.0) {
	prev_ray_len = length(view_cell);			prev_ray_len = length(view_cell);
	orig_ray_len = prev_ray_len / view_cell.z;			orig_ray_len = prev_ray_len / view_cell.z;
	}			}

	/* Without compute shader and arbitrary write we need to			#ifdef USE_VOLUME_OPTI
	* accumulate from the beginning of the ray for each cell. */			int slice = textureSize(volumeScattering, 0).z;
	float integration_end = float(slice);			ivec2 texco = ivec2(gl_FragCoord.xy);
				#endif
	for (int i = 0; i < slice; i++) {			for (int i = 0; i < slice; i++) {
	ivec3 volume_cell = ivec3(gl_FragCoord.xy, i);			ivec3 volume_cell = ivec3(gl_FragCoord.xy, i);

	vec3 Lscat = texelFetch(volumeScattering, volume_cell, 0).rgb;			vec3 Lscat = texelFetch(volumeScattering, volume_cell, 0).rgb;
	vec3 s_extinction = texelFetch(volumeExtinction, volume_cell, 0).rgb;			vec3 s_extinction = texelFetch(volumeExtinction, volume_cell, 0).rgb;

	float cell_depth = volume_z_to_view_z((float(i) + 1.0) / tex_size.z);			float cell_depth = volume_z_to_view_z((float(i) + 1.0) / tex_size.z);
	float ray_len = orig_ray_len * cell_depth;			float ray_len = orig_ray_len * cell_depth;

	/* Emission does not work of there is no extinction because			/* Emission does not work of there is no extinction because
	* Tr evaluates to 1.0 leading to Lscat = 0.0. (See T65771) */			* Tr evaluates to 1.0 leading to Lscat = 0.0. (See T65771) */
	s_extinction = max(vec3(1e-7) * step(1e-5, Lscat), s_extinction);			s_extinction = max(vec3(1e-7) * step(1e-5, Lscat), s_extinction);

	/* Evaluate Scattering */			/* Evaluate Scattering */
	float s_len = abs(ray_len - prev_ray_len);			float s_len = abs(ray_len - prev_ray_len);
	prev_ray_len = ray_len;			prev_ray_len = ray_len;
	vec3 Tr = exp(-s_extinction * s_len);			vec3 Tr = exp(-s_extinction * s_len);

	/* integrate along the current step segment */			/* integrate along the current step segment */
	Lscat = (Lscat - Lscat * Tr) / max(vec3(1e-8), s_extinction);			Lscat = (Lscat - Lscat * Tr) / max(vec3(1e-8), s_extinction);
	/* accumulate and also take into account the transmittance from previous steps */			/* accumulate and also take into account the transmittance from previous steps */
	finalScattering += finalTransmittance * Lscat;			finalScattering += finalTransmittance * Lscat;

	finalTransmittance *= Tr;			finalTransmittance *= Tr;

				#ifdef USE_VOLUME_OPTI
				ivec3 coord = ivec3(texco, i);
				imageStore(finalScattering_img, coord, vec4(finalScattering, 0.0));
				imageStore(finalTransmittance_img, coord, vec4(finalTransmittance, 0.0));
				#endif
	}			}
	}			}