Double buffer TAA’s accumulation buffer in preparation for last frame…

… reprojection (#6025)

Co-authored-by: Martin Valigursky <mvaligursky@snapchat.com>

extras/render-passes/render-pass-bloom.js

@@ -24,7 +24,7 @@ class RenderPassBloom extends RenderPass {
 
     constructor(device, sourceTexture, format) {
         super(device);
-        this.sourceTexture = sourceTexture;
+        this._sourceTexture = sourceTexture;
         this.textureFormat = format;
 
         this.bloomRenderTarget = this.createRenderTarget(0);
@@ -87,7 +87,7 @@ class RenderPassBloom extends RenderPass {
         const device = this.device;
 
         // progressive downscale
-        let passSourceTexture = this.sourceTexture;
+        let passSourceTexture = this._sourceTexture;
         for (let i = 0; i < numPasses; i++) {
 
             const pass = new RenderPassDownsample(device, passSourceTexture);
@@ -124,11 +124,29 @@ class RenderPassBloom extends RenderPass {
         this.destroyRenderTargets(1);
     }
 
+    set sourceTexture(value) {
+        this._sourceTexture = value;
+
+        if (this.beforePasses.length > 0) {
+            const firstPass = this.beforePasses[0];
+
+            // change resize source
+            firstPass.options.resizeSource = value;
+
+            // change downsample source
+            firstPass.sourceTexture = value;
+        }
+    }
+
+    get sourceTexture() {
+        return this._sourceTexture;
+    }
+
     frameUpdate() {
         super.frameUpdate();
 
         // create an appropriate amount of render passes
-        let numPasses = this.calcMipLevels(this.sourceTexture.width, this.sourceTexture.height, 2 ** this.lastMipLevel);
+        let numPasses = this.calcMipLevels(this._sourceTexture.width, this._sourceTexture.height, 2 ** this.lastMipLevel);
         numPasses = Math.max(1, numPasses);
 
         if (this.renderTargets.length !== numPasses) {

extras/render-passes/render-pass-camera-frame.js

@@ -23,6 +23,8 @@ class RenderPassCameraFrame extends RenderPass {
 
     bloomPass;
 
+    taaPass;
+
     _bloomEnabled = true;
 
     _renderTargetScale = 1;
@@ -174,11 +176,10 @@ class RenderPassCameraFrame extends RenderPass {
 
         // ------ TAA ------
 
-        let taaPass;
         let sceneTextureWithTaa = sceneTexture;
         if (options.taaEnabled) {
-            taaPass = new RenderPassTAA(device, sceneTexture);
-            sceneTextureWithTaa = taaPass.accumulationTexture;
+            this.taaPass = new RenderPassTAA(device, sceneTexture);
+            sceneTextureWithTaa = this.taaPass.accumulationTexture;
         }
 
         // ------ BLOOM GENERATION ------
@@ -190,7 +191,7 @@ class RenderPassCameraFrame extends RenderPass {
 
         // create a compose pass, which combines the scene texture with the bloom texture
         this.composePass = new RenderPassCompose(app.graphicsDevice);
-        this.composePass.sceneTexture = sceneTextureWithTaa;
+        // this.composePass.sceneTexture = sceneTextureWithTaa;
         this.composePass.bloomTexture = this.bloomPass.bloomTexture;
 
         // compose pass renders directly to target renderTarget
@@ -206,9 +207,23 @@ class RenderPassCameraFrame extends RenderPass {
         afterPass.addLayers(composition, cameraComponent, lastAddedIndex, clearRenderTarget);
 
         // use these prepared render passes in the order they should be executed
-        const allPasses = [this.scenePass, colorGrabPass, scenePassTransparent, taaPass, this.bloomPass, this.composePass, afterPass];
+        const allPasses = [this.scenePass, colorGrabPass, scenePassTransparent, this.taaPass, this.bloomPass, this.composePass, afterPass];
         this.beforePasses = allPasses.filter(element => element !== undefined);
     }
+
+    frameUpdate() {
+
+        super.frameUpdate();
+
+        // scene texture is either output of taa pass or the scene render target
+        const sceneTexture = this.taaPass?.update() ?? this._rt.colorBuffer;
+
+        // TAA accumulation buffer is double buffered, assign the current one to the follow up passes.
+        this.composePass.sceneTexture = sceneTexture;
+        if (this.bloomEnabled) {
+            this.bloomPass.sourceTexture = sceneTexture;
+        }
+    }
 }
 
 export { RenderPassCameraFrame };

extras/render-passes/render-pass-taa.js

@@ -1,18 +1,29 @@
 import {
     FILTER_LINEAR, ADDRESS_CLAMP_TO_EDGE,
-    BLENDEQUATION_ADD, BLENDMODE_CONSTANT, BLENDMODE_ONE_MINUS_CONSTANT,
-    Color,
-    BlendState,
     RenderPassShaderQuad,
     Texture,
     RenderTarget
 } from "playcanvas";
 
 class RenderPassTAA extends RenderPassShaderQuad {
     /**
-     * @type {Texture}
+     * The index of the accumulation texture to render to.
+     *
+     * @type {number}
      */
-    accumulationTexture;
+    accumulationIndex = 0;
+
+    accumulationTexture = null;
+
+    /**
+     * @type {Texture[]}
+     */
+    accumulationTextures = [];
+
+    /**
+     * @type {RenderTarget[]}
+     */
+    accumulationRenderTargets = [];
 
     constructor(device, sourceTexture) {
         super(device);
@@ -21,18 +32,19 @@ class RenderPassTAA extends RenderPassShaderQuad {
         this.shader = this.createQuadShader('TaaResolveShader', `
 
             uniform sampler2D sourceTexture;
+            uniform sampler2D accumulationTexture;
             varying vec2 uv0;
 
             void main()
             {
                 vec4 src = texture2D(sourceTexture, uv0);
-                gl_FragColor = src;
+                vec4 acc = texture2D(accumulationTexture, uv0);
+                gl_FragColor = mix(acc, src, 0.05);
             }`
         );
 
         this.sourceTextureId = device.scope.resolve('sourceTexture');
-
-        this.blendState = new BlendState(true, BLENDEQUATION_ADD, BLENDMODE_CONSTANT, BLENDMODE_ONE_MINUS_CONSTANT);
+        this.accumulationTextureId = device.scope.resolve('accumulationTexture');
 
         this.setup();
     }
@@ -47,46 +59,48 @@ class RenderPassTAA extends RenderPassShaderQuad {
 
     setup() {
 
-        const { device } = this;
-
-        // create the accumulation render target
-        const texture = new Texture(device, {
-            name: 'TAA Accumulation Texture',
-            width: 4,
-            height: 4,
-            format: this.sourceTexture.format,
-            mipmaps: false,
-            minFilter: FILTER_LINEAR,
-            magFilter: FILTER_LINEAR,
-            addressU: ADDRESS_CLAMP_TO_EDGE,
-            addressV: ADDRESS_CLAMP_TO_EDGE
-        });
-        this.accumulationTexture = texture;
-
-        const rt = new RenderTarget({
-            colorBuffer: texture,
-            depth: false
-        });
+        // double buffered accumulation render target
+        for (let i = 0; i < 2; ++i) {
+            this.accumulationTextures[i] = new Texture(this.device, {
+                name: `TAA-Accumulation-${i}`,
+                width: 4,
+                height: 4,
+                format: this.sourceTexture.format,
+                mipmaps: false,
+                minFilter: FILTER_LINEAR,
+                magFilter: FILTER_LINEAR,
+                addressU: ADDRESS_CLAMP_TO_EDGE,
+                addressV: ADDRESS_CLAMP_TO_EDGE
+            });
+
+            this.accumulationRenderTargets[i] = new RenderTarget({
+                colorBuffer: this.accumulationTextures[i],
+                depth: false
+            });
+        }
 
-        this.init(rt, {
+        this.accumulationTexture = this.accumulationTextures[0];
+        this.init(this.accumulationRenderTargets[0], {
             resizeSource: this.sourceTexture
         });
-
-        // clear it to black initially
-        this.setClearColor(Color.BLACK);
     }
 
     execute() {
         this.sourceTextureId.setValue(this.sourceTexture);
-
-        // TODO: add this to the parent class
-        const blend = 0.05;
-        this.device.setBlendColor(blend, blend, blend, blend);
+        this.accumulationTextureId.setValue(this.accumulationTextures[1 - this.accumulationIndex]);
 
         super.execute();
+    }
+
+    // called when the parent render pass gets added to the frame graph
+    update() {
+
+        // swap source and destination accumulation texture
+        this.accumulationIndex = 1 - this.accumulationIndex;
+        this.accumulationTexture = this.accumulationTextures[this.accumulationIndex];
+        this.renderTarget = this.accumulationRenderTargets[this.accumulationIndex];
 
-        // disable clearing
-        this.setClearColor();
+        return this.accumulationTexture;
     }
 }