TSL: Add CDLNode

src/nodes/Nodes.js

@@ -83,6 +83,7 @@ export { default as UserDataNode } from './accessors/UserDataNode.js';
 
 // display
 export { default as BumpMapNode } from './display/BumpMapNode.js';
+export { default as CDLNode } from './display/CDLNode.js';
 export { default as ColorSpaceNode } from './display/ColorSpaceNode.js';
 export { default as FrontFacingNode } from './display/FrontFacingNode.js';
 export { default as NormalMapNode } from './display/NormalMapNode.js';

src/nodes/TSL.js

@@ -84,6 +84,7 @@ export * from './accessors/VelocityNode.js';
 // display
 export * from './display/BlendMode.js';
 export * from './display/BumpMapNode.js';
+export * from './display/CDLNode.js';
 export * from './display/ColorAdjustment.js';
 export * from './display/ColorSpaceNode.js';
 export * from './display/FrontFacingNode.js';

src/nodes/display/CDLNode.js

@@ -0,0 +1,83 @@
+import TempNode from '../core/TempNode.js';
+import { Fn, nodeObject, vec3, vec4 } from '../tsl/TSLBase.js';
+import { max } from '../math/MathNode.js';
+import { LinearSRGBColorSpace } from '../../constants.js';
+import { ColorManagement } from '../../math/ColorManagement.js';
+import { Vector3 } from '../../math/Vector3.js';
+
+/**
+ * Color Decision List (CDL) v1.2
+ *
+ * References:
+ * - ASC CDL v1.2
+ * - https://blender.stackexchange.com/a/55239/43930
+ * - https://docs.acescentral.com/specifications/acescc/
+ */
+class CDLNode extends TempNode {
+
+	static get type() {
+
+		return 'CDLNode';
+
+	}
+
+	constructor( inputNode, slopeNode, offsetNode, powerNode, saturationNode ) {
+
+		super();
+
+		this.inputNode = inputNode;
+		this.slopeNode = slopeNode;
+		this.offsetNode = offsetNode;
+		this.powerNode = powerNode;
+		this.saturationNode = saturationNode;
+
+		// ASC CDL v1.2 explicitly requires Rec. 709 luminance coefficients, without input conversion to Rec. 709.
+		this.luminanceCoefficients = ColorManagement.getLuminanceCoefficients( new Vector3(), LinearSRGBColorSpace );
+
+	}
+
+	setup() {
+
+		const { inputNode, slopeNode, offsetNode, powerNode, saturationNode, luminanceCoefficients } = this;
+
+		const cdl = Fn( () => {
+
+			// NOTE: The ASC CDL v1.2 defines a [0, 1] clamp on slope+offset output,
+			// and another on saturation output. As discussed in ACEScc specification
+			// notes on CDL application, the limits may be omitted to support values >1
+			// if negative inputs to the power expression are avoided.
+			//
+			// We use `max( in, 0.0 )` for this reason, but the lower limit may not be
+			// required in all cases.
+
+			const luma = inputNode.rgb.dot( vec3( luminanceCoefficients ) );
+
+			// clamp( ( in * slope ) + offset ) ^ power
+			const output = max( inputNode.rgb.mul( slopeNode ).add( offsetNode ), 0.0 ).pow( powerNode ).toVar();
+
+			// clamp( luma + sat * ( in - luma ) )
+			output.assign( max( luma.add( saturationNode.mul( output.sub( luma ) ) ), 0.0 ) );
+
+			return vec4( output.rgb, inputNode.a );
+
+		} );
+
+		const outputNode = cdl();
+
+		return outputNode;
+
+	}
+
+}
+
+export default CDLNode;
+
+export const cdl = ( node, slope, offset, power, saturation ) => nodeObject(
+	new CDLNode(
+		nodeObject( node ),
+		nodeObject( slope ),
+		nodeObject( offset ),
+		nodeObject( power ),
+		nodeObject( saturation )
+	)
+);