multistep <1spp expand

implicit3-rt/frag-render.glsl

@@ -1310,7 +1310,7 @@ void main(void) {
                 float u = dot(col, ru), v = dot(col, rv), w = dot(col, rd);
                 totcol = vec4(u, v, w, u*u+v*v);
             }
-            else totcol += vec4(col, 1) / sSamples;
+            else totcol += vec4(col, 1);
         }
     }
     fragColor = totcol;

scripts/render-rt.js

@@ -5,14 +5,17 @@ var renderer = {
     gl: null,
     renderSource: "",
     copySource: "",
+    expandSource: "",
     postSource: "",
     tonemapSource: "",
     positionBuffer: null,
     renderProgram: null,
     copyProgram: null,
+    expandProgram: null,
     postProgram: null,
     renderTarget: null,
     renderTargetAccum: null,
+    expandTarget: null,
     denoiseTarget: null,
     tonemapProgram: null,
     tonemapTarget: null,
@@ -153,11 +156,16 @@ async function drawScene(state, transformMatrix, lightDir) {
         }
     }
 
+    let outputFramebuffer = renderer.denoiser ?
+        renderer.denoiseTarget.framebuffer :
+        renderer.tonemapTarget.framebuffer;
+    let fractionalSpp = state.iSpp < (renderer.denoiser ? 2 : 2);
+
     // post processing
     gl.useProgram(renderer.postProgram);
-    gl.bindFramebuffer(gl.FRAMEBUFFER, renderer.denoiser ?
-        renderer.denoiseTarget.framebuffer :
-        renderer.tonemapTarget.framebuffer);
+    gl.bindFramebuffer(gl.FRAMEBUFFER, fractionalSpp ?
+        renderer.expandTarget.framebuffer : outputFramebuffer
+    );
     setPositionBuffer(gl, renderer.postProgram);
     gl.activeTexture(gl.TEXTURE0);
     gl.bindTexture(gl.TEXTURE_2D, renderer.renderTargetAccum.texture);
@@ -171,6 +179,30 @@ async function drawScene(state, transformMatrix, lightDir) {
         state.iSpp+state.sSamples);
     renderPass();
 
+    // expand for <1spp
+    if (fractionalSpp) {
+        gl.useProgram(renderer.expandProgram);
+        gl.bindFramebuffer(gl.FRAMEBUFFER, outputFramebuffer);
+        setPositionBuffer(gl, renderer.expandProgram);
+        gl.activeTexture(gl.TEXTURE0);
+        gl.bindTexture(gl.TEXTURE_2D, renderer.expandTarget.texture);
+        gl.uniform1i(gl.getUniformLocation(renderer.expandProgram, "iChannel0"), 0);
+        renderPass();
+    }
+    var niter = state.iSpp<1.0/64.0 ? 3 :
+            state.iSpp<1.0/16.0 ? 2 :
+            state.iSpp<1.0/4.0 ? 1 : 0;
+    for (var i = 0; i < niter; i++) {
+        gl.bindTexture(gl.TEXTURE_2D, renderer.expandTarget.sampler);
+        gl.copyTexImage2D(gl.TEXTURE_2D,
+            0, gl.RGBA32F, 0, 0, state.width, state.height, 0);
+        setPositionBuffer(gl, renderer.expandProgram);
+        gl.activeTexture(gl.TEXTURE0);
+        gl.bindTexture(gl.TEXTURE_2D, renderer.expandTarget.sampler);
+        gl.uniform1i(gl.getUniformLocation(renderer.expandProgram, "iChannel0"), 0);
+        renderPass();
+    }
+
     // denoising
     if (renderer.denoiser) {
         gl.bindTexture(gl.TEXTURE_2D, renderer.denoiseTarget.sampler);
@@ -308,6 +340,7 @@ function initWebGL() {
         "void main(){vXy=vertexPosition.xy;gl_Position=vertexPosition;}";
     renderer.renderSource = getShaderSource("frag-render.glsl");
     renderer.copySource = getShaderSource("../shaders/frag-copy.glsl");
+    renderer.expandSource = getShaderSource("../shaders/frag-rt-expand.glsl");
     renderer.postSource = getShaderSource("../shaders/frag-rt-post.glsl");
     renderer.tonemapSource = getShaderSource("../shaders/frag-tonemap.glsl");
     console.timeEnd("load glsl code");
@@ -369,6 +402,10 @@ function updateBuffers() {
     renderer.renderTargetNormal = createRenderTarget(gl, state.width, state.height, false, true, true);
     if (oldRenderTargetNormal) destroyRenderTarget(gl, oldRenderTargetNormal);
 
+    var oldExpandTarget = renderer.expandTarget;
+    renderer.expandTarget = createRenderTarget(gl, state.width, state.height, false, true, true);
+    if (oldExpandTarget) destroyRenderTarget(gl, oldExpandTarget);
+
     var oldDenoiseTarget = renderer.denoiseTarget;
     renderer.denoiseTarget = createRenderTarget(gl, state.width, state.height, false, true, true);
     if (oldDenoiseTarget) destroyRenderTarget(gl, oldDenoiseTarget);
@@ -625,9 +662,10 @@ function updateShaderFunction(funCode, funGradCode, params) {
         prevCode.tonemapSource = tonemapSource;
     }
 
-    if (!renderer.copyProgram) {
+    if (!renderer.copyProgram)
         renderer.copyProgram = createShaderProgram(gl, null, renderer.copySource);
-    }
+    if (!renderer.expandProgram)
+        renderer.expandProgram = createShaderProgram(gl, null, renderer.expandSource);
     if (!renderer.postProgram)
         renderer.postProgram = createShaderProgram(gl, null, renderer.postSource);
 

shaders/frag-rt-expand.glsl

@@ -0,0 +1,29 @@
+#version 300 es
+precision highp float;
+
+uniform sampler2D iChannel0;
+out vec4 fragColor;
+
+void main(void) {
+
+    vec4 x = vec4(0);
+    for (float s = 0.; s < 3.; s++) {
+        mat2 m = mat2(1);
+        for (float r = 0.; r < 4.; r++) {
+            for (float l = 0.; l < 2.*s; l++) {
+                vec2 p = gl_FragCoord.xy + m * vec2(s, s-l);
+                x = texelFetch(iChannel0, ivec2(p)-1, 0);
+                if (x.w > 0.0) break;
+            }
+            if (x.w > 0.0) break;
+            m = mat2(1,1,-1,1) * m;
+        }
+        if (x.w > 0.0) break;
+    }
+    x /= x.w;
+
+    if (isnan(x.x+x.y+x.z))
+        x = vec4(0);
+
+    fragColor = x;
+}

shaders/frag-rt-post.glsl

@@ -12,8 +12,12 @@ void main(void) {
     vec4 pixel0 = texelFetch(iChannel0, ivec2(gl_FragCoord.xy), 0);
     vec4 pixel1 = texelFetch(iChannel1, ivec2(gl_FragCoord.xy), 0);
     vec4 pixel = pixel0 + pixel1;
+    if (pixel.w == 0.0) {
+        fragColor = vec4(0);
+        return;
+    }
     vec3 col = max(pixel.xyz/pixel.w, 0.0);
     fragColor = denoise ?
-        vec4(log(pow(col/min(iSpp,1.0), vec3(1.0/2.2))+1.0), 0.0) :
+        vec4(log(pow(col, vec3(1.0/2.2))+1.0), 1.0) :
         vec4(col, 1.0) * pixel.w;
 }

shaders/frag-tonemap.glsl

@@ -31,20 +31,7 @@ vec3 tonemapUncharted2(vec3 x) {
 
 void main(void) {
 
-    vec4 x = vec4(0);
-    for (float s = 0.; s < 16.; s++) {
-        mat2 m = mat2(1);
-        for (float r = 0.; r < 4.; r++) {
-            for (float l = 0.; l < 2.*s; l++) {
-                vec2 p = gl_FragCoord.xy + m * vec2(s, s-l);
-                x = texelFetch(iChannel0, ivec2(p), 0);
-                if (x.w > 0.0) break;
-            }
-            if (x.w > 0.0) break;
-            m = mat2(1,1,-1,1) * m;
-        }
-        if (x.w > 0.0) break;
-    }
+    vec4 x = texelFetch(iChannel0, ivec2(gl_FragCoord.xy), 0);
     x /= x.w;
 
     x.xyz = tonemap{%TONEMAP%}(x.xyz);