TSL: Add CDLNode

src/nodes/display/ColorAdjustment.js

@@ -1,8 +1,9 @@
-import { dot, mix } from '../math/MathNode.js';
+import { dot, max, mix } from '../math/MathNode.js';
 import { add } from '../math/OperatorNode.js';
-import { Fn, float, vec3 } from '../tsl/TSLBase.js';
+import { Fn, If, float, vec3, vec4 } from '../tsl/TSLBase.js';
 import { ColorManagement } from '../../math/ColorManagement.js';
 import { Vector3 } from '../../math/Vector3.js';
+import { LinearSRGBColorSpace } from '../../constants.js';
 
 export const grayscale = /*@__PURE__*/ Fn( ( [ color ] ) => {
 
@@ -44,3 +45,52 @@ export const luminance = (
 ) => dot( color, luminanceCoefficients );
 
 export const threshold = ( color, threshold ) => mix( vec3( 0.0 ), color, luminance( color ).sub( threshold ).max( 0 ) );
+
+/**
+ * Color Decision List (CDL) v1.2
+ *
+ * Compact representation of color grading information, defined by slope, offset, power, and
+ * saturation. The CDL should be typically be given input in a log space (such as LogC, ACEScc,
+ * or AgX Log), and will return output in the same space. Output may require clamping >=0.
+ *
+ * @param {vec4} color Input (-Infinity < input < +Infinity)
+ * @param {number | vec3} slope Slope (0 ≤ slope < +Infinity)
+ * @param {number | vec3} offset Offset (-Infinity < offset < +Infinity; typically -1 < offset < 1)
+ * @param {number | vec3} power Power (0 < power < +Infinity)
+ * @param {number} saturation Saturation (0 ≤ saturation < +Infinity; typically 0 ≤ saturation < 4)
+ * @param {vec3} luminanceCoefficients Luminance coefficients for saturation term, typically Rec. 709
+ * @return Output, -Infinity < output < +Infinity
+ *
+ * References:
+ * - ASC CDL v1.2
+ * - https://blender.stackexchange.com/a/55239/43930
+ * - https://docs.acescentral.com/specifications/acescc/
+ */
+export const cdl = /*@__PURE__*/ Fn( ( [
+	color,
+	slope = vec3( 1 ),
+	offset = vec3( 0 ),
+	power = vec3( 1 ),
+	saturation = float( 1 ),
+	// ASC CDL v1.2 explicitly requires Rec. 709 luminance coefficients.
+	luminanceCoefficients = vec3( ColorManagement.getLuminanceCoefficients( new Vector3(), LinearSRGBColorSpace ) )
+] ) => {
+
+	// NOTE: The ASC CDL v1.2 defines a [0, 1] clamp on the slope+offset term, and another on the
+	// saturation term. Per the ACEScc specification and Filament, limits may be omitted to support
+	// values outside [0, 1], requiring a workaround for negative values in the power expression.
+
+	const luma = color.rgb.dot( vec3( luminanceCoefficients ) );
+
+	const v = max( color.rgb.mul( slope ).add( offset ), 0.0 ).toVar();
+	const pv = v.pow( power ).toVar();
+
+	If( v.r.greaterThan( 0.0 ), () => { v.r.assign( pv.r ); } ); // eslint-disable-line
+	If( v.g.greaterThan( 0.0 ), () => { v.g.assign( pv.g ); } ); // eslint-disable-line
+	If( v.b.greaterThan( 0.0 ), () => { v.b.assign( pv.b ); } ); // eslint-disable-line
+
+	v.assign( luma.add( v.sub( luma ).mul( saturation ) ) );
+
+	return vec4( v.rgb, color.a );
+
+} );