Clément Foucault
98dd2a518b
The problem was that orthographic views can have hit position that are negative. Thus we cannot encode the hit in the sign of the Z component. The workaround is to store the hit position in screenspace. But since we are using floating point render target, we are loosing quite a bit of precision. TODO: use RGBA16 instead of RGBA16F. But that means encoding the pdf value somehow.
446 lines
14 KiB
GLSL
446 lines
14 KiB
GLSL
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/* Based on Stochastic Screen Space Reflections
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* https://www.ea.com/frostbite/news/stochastic-screen-space-reflections */
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#ifndef UTIL_TEX
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#define UTIL_TEX
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uniform sampler2DArray utilTex;
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#endif /* UTIL_TEX */
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#define BRDF_BIAS 0.7
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#define MAX_MIP 9.0
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#ifdef STEP_RAYTRACE
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uniform sampler2D normalBuffer;
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uniform sampler2D specroughBuffer;
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uniform int planar_count;
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uniform float noiseOffset;
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layout(location = 0) out vec4 hitData0;
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layout(location = 1) out vec4 hitData1;
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layout(location = 2) out vec4 hitData2;
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layout(location = 3) out vec4 hitData3;
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vec4 do_planar_ssr(int index, vec3 V, vec3 N, vec3 T, vec3 B, vec3 planeNormal, vec3 viewPosition, float a2, vec3 rand, float ofs)
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{
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float pdf, NH;
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float jitter = fract(rand.x + ofs);
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/* Importance sampling bias */
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rand.x = mix(rand.x, 0.0, BRDF_BIAS);
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vec3 H = sample_ggx(rand, a2, N, T, B, NH); /* Microfacet normal */
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pdf = pdf_ggx_reflect(NH, a2);
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vec3 R = reflect(-V, H);
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R = reflect(R, planeNormal);
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/* If ray is bad (i.e. going below the plane) regenerate. */
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if (dot(R, planeNormal) > 0.0) {
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vec3 H = sample_ggx(rand * vec3(1.0, -1.0, -1.0), a2, N, T, B, NH); /* Microfacet normal */
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pdf = pdf_ggx_reflect(NH, a2);
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R = reflect(-V, H);
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R = reflect(R, planeNormal);
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}
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pdf = min(1024e32, pdf); /* Theoretical limit of 16bit float */
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pdf *= -1.0; /* Tag as planar ray. */
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/* Since viewspace hit position can land behind the camera in this case,
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* we save the reflected view position (visualize it as the hit position
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* below the reflection plane). This way it's garanted that the hit will
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* be in front of the camera. That let us tag the bad rays with a negative
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* sign in the Z component. */
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vec3 hit_pos = raycast(index, viewPosition, R, 1e16, jitter, a2);
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return vec4(hit_pos, pdf);
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}
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vec4 do_ssr(vec3 V, vec3 N, vec3 T, vec3 B, vec3 viewPosition, float a2, vec3 rand, float ofs)
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{
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float pdf, NH;
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float jitter = fract(rand.x + ofs);
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/* Importance sampling bias */
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rand.x = mix(rand.x, 0.0, BRDF_BIAS);
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vec3 H = sample_ggx(rand, a2, N, T, B, NH); /* Microfacet normal */
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pdf = pdf_ggx_reflect(NH, a2);
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vec3 R = reflect(-V, H);
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pdf = min(1024e32, pdf); /* Theoretical limit of 16bit float */
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vec3 hit_pos = raycast(-1, viewPosition, R, ssrThickness, jitter, a2);
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return vec4(hit_pos, pdf);
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}
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void main()
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{
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#ifdef FULLRES
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ivec2 fullres_texel = ivec2(gl_FragCoord.xy);
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ivec2 halfres_texel = fullres_texel;
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#else
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ivec2 fullres_texel = ivec2(gl_FragCoord.xy) * 2;
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ivec2 halfres_texel = ivec2(gl_FragCoord.xy);
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#endif
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float depth = texelFetch(depthBuffer, fullres_texel, 0).r;
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/* Early out */
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if (depth == 1.0)
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discard;
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vec2 uvs = gl_FragCoord.xy / vec2(textureSize(depthBuffer, 0));
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#ifndef FULLRES
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uvs *= 2.0;
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#endif
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/* Using view space */
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vec3 viewPosition = get_view_space_from_depth(uvs, depth);
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vec3 V = viewCameraVec;
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vec3 N = normal_decode(texelFetch(normalBuffer, fullres_texel, 0).rg, V);
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/* Retrieve pixel data */
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vec4 speccol_roughness = texelFetch(specroughBuffer, fullres_texel, 0).rgba;
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/* Early out */
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if (dot(speccol_roughness.rgb, vec3(1.0)) == 0.0)
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discard;
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float roughness = speccol_roughness.a;
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float roughnessSquared = max(1e-3, roughness * roughness);
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float a2 = roughnessSquared * roughnessSquared;
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if (roughness > maxRoughness + 0.2) {
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hitData0 = hitData1 = hitData2 = hitData3 = vec4(0.0);
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return;
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}
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vec3 rand = texelFetch(utilTex, ivec3(halfres_texel % LUT_SIZE, 2), 0).rba;
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vec3 worldPosition = transform_point(ViewMatrixInverse, viewPosition);
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vec3 wN = transform_direction(ViewMatrixInverse, N);
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vec3 T, B;
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make_orthonormal_basis(N, T, B); /* Generate tangent space */
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/* Planar Reflections */
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for (int i = 0; i < MAX_PLANAR && i < planar_count; ++i) {
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PlanarData pd = planars_data[i];
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float fade = probe_attenuation_planar(pd, worldPosition, wN, 0.0);
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if (fade > 0.5) {
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/* Find view vector / reflection plane intersection. */
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/* TODO optimize, use view space for all. */
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vec3 tracePosition = line_plane_intersect(worldPosition, cameraVec, pd.pl_plane_eq);
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tracePosition = transform_point(ViewMatrix, tracePosition);
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vec3 planeNormal = transform_direction(ViewMatrix, pd.pl_normal);
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hitData0 = do_planar_ssr(i, V, N, T, B, planeNormal, tracePosition, a2, rand, 0.0);
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#if (RAY_COUNT > 1)
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hitData1 = do_planar_ssr(i, V, N, T, B, planeNormal, tracePosition, a2, rand.xyz * vec3(1.0, -1.0, -1.0), 1.0 / float(RAY_COUNT));
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#endif
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#if (RAY_COUNT > 2)
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hitData2 = do_planar_ssr(i, V, N, T, B, planeNormal, tracePosition, a2, rand.xzy * vec3(1.0, 1.0, -1.0), 2.0 / float(RAY_COUNT));
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#endif
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#if (RAY_COUNT > 3)
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hitData3 = do_planar_ssr(i, V, N, T, B, planeNormal, tracePosition, a2, rand.xzy * vec3(1.0, -1.0, 1.0), 3.0 / float(RAY_COUNT));
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#endif
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return;
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}
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}
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/* TODO : Raytrace together if textureGather is supported. */
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hitData0 = do_ssr(V, N, T, B, viewPosition, a2, rand, 0.0);
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#if (RAY_COUNT > 1)
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hitData1 = do_ssr(V, N, T, B, viewPosition, a2, rand.xyz * vec3(1.0, -1.0, -1.0), 1.0 / float(RAY_COUNT));
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#endif
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#if (RAY_COUNT > 2)
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hitData2 = do_ssr(V, N, T, B, viewPosition, a2, rand.xzy * vec3(1.0, 1.0, -1.0), 2.0 / float(RAY_COUNT));
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#endif
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#if (RAY_COUNT > 3)
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hitData3 = do_ssr(V, N, T, B, viewPosition, a2, rand.xzy * vec3(1.0, -1.0, 1.0), 3.0 / float(RAY_COUNT));
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#endif
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}
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#else /* STEP_RESOLVE */
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uniform sampler2D prevColorBuffer; /* previous frame */
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uniform sampler2D normalBuffer;
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uniform sampler2D specroughBuffer;
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uniform sampler2D hitBuffer0;
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uniform sampler2D hitBuffer1;
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uniform sampler2D hitBuffer2;
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uniform sampler2D hitBuffer3;
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uniform int probe_count;
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uniform int planar_count;
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uniform mat4 PastViewProjectionMatrix;
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out vec4 fragColor;
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void fallback_cubemap(vec3 N, vec3 V, vec3 W, float roughness, float roughnessSquared, inout vec4 spec_accum)
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{
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/* Specular probes */
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vec3 spec_dir = get_specular_reflection_dominant_dir(N, V, roughnessSquared);
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/* Starts at 1 because 0 is world probe */
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for (int i = 1; i < MAX_PROBE && i < probe_count && spec_accum.a < 0.999; ++i) {
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CubeData cd = probes_data[i];
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float fade = probe_attenuation_cube(cd, W);
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if (fade > 0.0) {
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vec3 spec = probe_evaluate_cube(float(i), cd, W, spec_dir, roughness);
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accumulate_light(spec, fade, spec_accum);
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}
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}
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/* World Specular */
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if (spec_accum.a < 0.999) {
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vec3 spec = probe_evaluate_world_spec(spec_dir, roughness);
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accumulate_light(spec, 1.0, spec_accum);
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}
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}
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#if 0 /* Finish reprojection with motion vectors */
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vec3 get_motion_vector(vec3 pos)
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{
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}
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/* http://bitsquid.blogspot.fr/2017/06/reprojecting-reflections_22.html */
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vec3 find_reflection_incident_point(vec3 cam, vec3 hit, vec3 pos, vec3 N)
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{
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float d_cam = point_plane_projection_dist(cam, pos, N);
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float d_hit = point_plane_projection_dist(hit, pos, N);
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if (d_hit < d_cam) {
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/* Swap */
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float tmp = d_cam;
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d_cam = d_hit;
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d_hit = tmp;
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}
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vec3 proj_cam = cam - (N * d_cam);
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vec3 proj_hit = hit - (N * d_hit);
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return (proj_hit - proj_cam) * d_cam / (d_cam + d_hit) + proj_cam;
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}
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#endif
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float brightness(vec3 c)
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{
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return max(max(c.r, c.g), c.b);
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}
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vec2 get_reprojected_reflection(vec3 hit, vec3 pos, vec3 N)
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{
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/* TODO real reprojection with motion vectors, etc... */
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return project_point(PastViewProjectionMatrix, hit).xy * 0.5 + 0.5;
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}
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vec4 get_ssr_sample(
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sampler2D hitBuffer, PlanarData pd, float planar_index, vec3 worldPosition, vec3 N, vec3 V, float roughnessSquared,
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float cone_tan, vec2 source_uvs, vec2 texture_size, ivec2 target_texel,
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inout float weight_acc)
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{
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vec4 hit_co_pdf = texelFetch(hitBuffer, target_texel, 0).rgba;
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bool has_hit = (hit_co_pdf.z > 0.0);
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bool is_planar = (hit_co_pdf.w < 0.0);
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hit_co_pdf.z = abs(hit_co_pdf.z);
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hit_co_pdf.w = abs(hit_co_pdf.w);
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/* Hit position in world space. */
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hit_co_pdf.xyz = get_view_space_from_depth(hit_co_pdf.xy, hit_co_pdf.z);
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vec3 hit_pos = transform_point(ViewMatrixInverse, hit_co_pdf.xyz);
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vec2 ref_uvs;
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vec3 hit_vec;
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float mask = 1.0;
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if (is_planar) {
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/* Reflect back the hit position to have it in non-reflected world space */
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vec3 trace_pos = line_plane_intersect(worldPosition, V, pd.pl_plane_eq);
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hit_vec = hit_pos - trace_pos;
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hit_vec = reflect(hit_vec, pd.pl_normal);
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ref_uvs = project_point(ProjectionMatrix, hit_co_pdf.xyz).xy * 0.5 + 0.5;
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}
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else {
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/* Find hit position in previous frame. */
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ref_uvs = get_reprojected_reflection(hit_pos, worldPosition, N);
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hit_vec = hit_pos - worldPosition;
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mask = screen_border_mask(gl_FragCoord.xy / texture_size);
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}
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mask = min(mask, screen_border_mask(ref_uvs));
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mask *= float(has_hit);
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float hit_dist = max(1e-8, length(hit_vec));
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vec3 L = hit_vec / hit_dist;
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float cone_footprint = hit_dist * cone_tan;
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/* Compute cone footprint in screen space. */
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float homcoord = ProjectionMatrix[2][3] * hit_co_pdf.z + ProjectionMatrix[3][3];
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cone_footprint = BRDF_BIAS * 0.5 * cone_footprint * max(ProjectionMatrix[0][0], ProjectionMatrix[1][1]) / homcoord;
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/* Estimate a cone footprint to sample a corresponding mipmap level. */
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float mip = clamp(log2(cone_footprint * max(texture_size.x, texture_size.y)), 0.0, MAX_MIP);
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/* Correct UVs for mipmaping mis-alignment */
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ref_uvs *= mip_ratio_interp(mip);
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/* Slide 54 */
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float bsdf = bsdf_ggx(N, L, V, roughnessSquared);
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float weight = step(1e-8, hit_co_pdf.w) * bsdf / max(1e-8, hit_co_pdf.w);
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weight_acc += weight;
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vec3 sample;
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if (is_planar) {
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sample = textureLod(probePlanars, vec3(ref_uvs, planar_index), mip).rgb;
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}
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else {
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sample = textureLod(prevColorBuffer, ref_uvs, mip).rgb;
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}
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/* Clamped brightness. */
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float luma = max(1e-8, brightness(sample));
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sample *= 1.0 - max(0.0, luma - fireflyFactor) / luma;
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/* Do not add light if ray has failed. */
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sample *= float(has_hit);
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/* Protection against NaNs in the history buffer.
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* This could be removed if some previous pass has already
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* sanitized the input. */
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if (any(isnan(sample))) {
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sample = vec3(0.0);
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weight = 0.0;
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}
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return vec4(sample, mask) * weight;
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}
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#define NUM_NEIGHBORS 4
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void main()
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{
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ivec2 fullres_texel = ivec2(gl_FragCoord.xy);
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#ifdef FULLRES
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ivec2 halfres_texel = fullres_texel;
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#else
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ivec2 halfres_texel = ivec2(gl_FragCoord.xy / 2.0);
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#endif
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vec2 texture_size = vec2(textureSize(depthBuffer, 0));
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vec2 uvs = gl_FragCoord.xy / texture_size;
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vec3 rand = texelFetch(utilTex, ivec3(fullres_texel % LUT_SIZE, 2), 0).rba;
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float depth = textureLod(depthBuffer, uvs, 0.0).r;
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/* Early out */
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if (depth == 1.0)
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discard;
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/* Using world space */
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vec3 viewPosition = get_view_space_from_depth(uvs, depth); /* Needed for viewCameraVec */
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vec3 worldPosition = transform_point(ViewMatrixInverse, viewPosition);
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vec3 V = cameraVec;
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vec3 vN = normal_decode(texelFetch(normalBuffer, fullres_texel, 0).rg, viewCameraVec);
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vec3 N = transform_direction(ViewMatrixInverse, vN);
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vec4 speccol_roughness = texelFetch(specroughBuffer, fullres_texel, 0).rgba;
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/* Early out */
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if (dot(speccol_roughness.rgb, vec3(1.0)) == 0.0)
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discard;
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/* Find Planar Reflections affecting this pixel */
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PlanarData pd;
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float planar_index;
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for (int i = 0; i < MAX_PLANAR && i < planar_count; ++i) {
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pd = planars_data[i];
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float fade = probe_attenuation_planar(pd, worldPosition, N, 0.0);
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if (fade > 0.5) {
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planar_index = float(i);
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break;
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}
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}
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float roughness = speccol_roughness.a;
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float roughnessSquared = max(1e-3, roughness * roughness);
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vec4 spec_accum = vec4(0.0);
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/* Resolve SSR */
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float cone_cos = cone_cosine(roughnessSquared);
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float cone_tan = sqrt(1 - cone_cos * cone_cos) / cone_cos;
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cone_tan *= mix(saturate(dot(N, -V) * 2.0), 1.0, roughness); /* Elongation fit */
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vec2 source_uvs = project_point(PastViewProjectionMatrix, worldPosition).xy * 0.5 + 0.5;
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vec4 ssr_accum = vec4(0.0);
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float weight_acc = 0.0;
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const ivec2 neighbors[9] = ivec2[9](
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ivec2(0, 0),
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ivec2(0, 1),
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ivec2(-1, -1), ivec2(1, -1),
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ivec2(-1, 1), ivec2(1, 1),
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ivec2(0, -1),
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ivec2(-1, 0), ivec2(1, 0)
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);
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ivec2 invert_neighbor;
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invert_neighbor.x = ((fullres_texel.x & 0x1) == 0) ? 1 : -1;
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invert_neighbor.y = ((fullres_texel.y & 0x1) == 0) ? 1 : -1;
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if (roughness < maxRoughness + 0.2) {
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for (int i = 0; i < NUM_NEIGHBORS; i++) {
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ivec2 target_texel = halfres_texel + neighbors[i] * invert_neighbor;
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ssr_accum += get_ssr_sample(hitBuffer0, pd, planar_index, worldPosition, N, V,
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roughnessSquared, cone_tan, source_uvs,
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texture_size, target_texel, weight_acc);
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#if (RAY_COUNT > 1)
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ssr_accum += get_ssr_sample(hitBuffer1, pd, planar_index, worldPosition, N, V,
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roughnessSquared, cone_tan, source_uvs,
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texture_size, target_texel, weight_acc);
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#endif
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#if (RAY_COUNT > 2)
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ssr_accum += get_ssr_sample(hitBuffer2, pd, planar_index, worldPosition, N, V,
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roughnessSquared, cone_tan, source_uvs,
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texture_size, target_texel, weight_acc);
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#endif
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#if (RAY_COUNT > 3)
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ssr_accum += get_ssr_sample(hitBuffer3, pd, planar_index, worldPosition, N, V,
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roughnessSquared, cone_tan, source_uvs,
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texture_size, target_texel, weight_acc);
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#endif
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}
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}
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/* Compute SSR contribution */
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if (weight_acc > 0.0) {
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ssr_accum /= weight_acc;
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/* fade between 0.5 and 1.0 roughness */
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ssr_accum.a *= smoothstep(maxRoughness + 0.2, maxRoughness, roughness);
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accumulate_light(ssr_accum.rgb, ssr_accum.a, spec_accum);
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}
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/* If SSR contribution is not 1.0, blend with cubemaps */
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if (spec_accum.a < 1.0) {
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fallback_cubemap(N, V, worldPosition, roughness, roughnessSquared, spec_accum);
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}
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fragColor = vec4(spec_accum.rgb * speccol_roughness.rgb, 1.0);
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}
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#endif
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