WebGLRenderer: Add support for AgX Tone Mapping

examples/webgl_tonemapping.html

@@ -49,6 +49,7 @@
 				Reinhard: THREE.ReinhardToneMapping,
 				Cineon: THREE.CineonToneMapping,
 				ACESFilmic: THREE.ACESFilmicToneMapping,
+				AgX: THREE.AgXToneMapping,
 				Custom: THREE.CustomToneMapping
 			};
 

src/constants.js

@@ -57,6 +57,7 @@ export const ReinhardToneMapping = 2;
 export const CineonToneMapping = 3;
 export const ACESFilmicToneMapping = 4;
 export const CustomToneMapping = 5;
+export const AgXToneMapping = 6;
 export const AttachedBindMode = 'attached';
 export const DetachedBindMode = 'detached';
 

src/renderers/shaders/ShaderChunk/tonemapping_pars_fragment.glsl.js

@@ -73,5 +73,78 @@ vec3 ACESFilmicToneMapping( vec3 color ) {
 
 }
 
+// AGX Tone Mapping implementation from
+// https://iolite-engine.com/blog_posts/minimal_agx_implementation
+// https://www.shadertoy.com/view/cd3XWr
+// Mean error^2: 3.6705141e-06
+vec3 agxDefaultContrastApprox( vec3 x ) {
+
+	vec3 x2 = x * x;
+	vec3 x4 = x2 * x2;
+
+	return + 15.5 * x4 * x2
+		- 40.14 * x4 * x
+		+ 31.96 * x4
+		- 6.868 * x2 * x
+		+ 0.4298 * x2
+		+ 0.1191 * x
+		- 0.00232;
+
+}
+
+vec3 agx( vec3 val ) {
+
+	const mat3 agx_mat = mat3(
+		0.842479062253094, 0.0423282422610123, 0.0423756549057051,
+		0.0784335999999992, 0.878468636469772, 0.0784336,
+		0.0792237451477643, 0.0791661274605434, 0.879142973793104
+	);
+
+	const float min_ev = -12.47393;
+	const float max_ev = 4.026069;
+
+	// Input transform (inset)
+	val = agx_mat * val;
+
+	// Log2 space encoding
+	val = clamp( log2( val ), min_ev, max_ev );
+	val = ( val - min_ev ) / ( max_ev - min_ev );
+
+	// Apply sigmoid function approximation
+	val = agxDefaultContrastApprox( val );
+
+	return val;
+
+}
+
+vec3 agxEotf( vec3 val ) {
+
+  	const mat3 agx_mat_inv = mat3(
+		1.19687900512017, -0.0528968517574562, -0.0529716355144438,
+		-0.0980208811401368, 1.15190312990417, -0.0980434501171241,
+		-0.0990297440797205, -0.0989611768448433, 1.15107367264116
+	);
+
+ 	// Inverse input transform (outset)
+	val = agx_mat_inv * val;
+
+	// sRGB IEC 61966-2-1 2.2 Exponent Reference EOTF Display
+	// NOTE: We're linearizing the output here. Comment/adjust when
+	// *not* using a sRGB render target
+	val = pow( val, vec3( 2.2 ) );
+
+	return val;
+
+}
+
+vec3 AgXToneMapping( vec3 color ) {
+
+	color *= toneMappingExposure;
+	color = agx( color );
+	color = agxEotf( color );
+	return color;
+
+}
+
 vec3 CustomToneMapping( vec3 color ) { return color; }
 `;

src/renderers/webgl/WebGLProgram.js

@@ -1,7 +1,7 @@
 import { WebGLUniforms } from './WebGLUniforms.js';
 import { WebGLShader } from './WebGLShader.js';
 import { ShaderChunk } from '../shaders/ShaderChunk.js';
-import { NoToneMapping, AddOperation, MixOperation, MultiplyOperation, CubeRefractionMapping, CubeUVReflectionMapping, CubeReflectionMapping, PCFSoftShadowMap, PCFShadowMap, VSMShadowMap, ACESFilmicToneMapping, CineonToneMapping, CustomToneMapping, ReinhardToneMapping, LinearToneMapping, GLSL3, LinearSRGBColorSpace, SRGBColorSpace, LinearDisplayP3ColorSpace, DisplayP3ColorSpace, P3Primaries, Rec709Primaries } from '../../constants.js';
+import { NoToneMapping, AddOperation, MixOperation, MultiplyOperation, CubeRefractionMapping, CubeUVReflectionMapping, CubeReflectionMapping, PCFSoftShadowMap, PCFShadowMap, VSMShadowMap, AgXToneMapping, ACESFilmicToneMapping, CineonToneMapping, CustomToneMapping, ReinhardToneMapping, LinearToneMapping, GLSL3, LinearSRGBColorSpace, SRGBColorSpace, LinearDisplayP3ColorSpace, DisplayP3ColorSpace, P3Primaries, Rec709Primaries } from '../../constants.js';
 import { ColorManagement } from '../../math/ColorManagement.js';
 
 // From https://www.khronos.org/registry/webgl/extensions/KHR_parallel_shader_compile/
@@ -120,6 +120,10 @@ function getToneMappingFunction( functionName, toneMapping ) {
 			toneMappingName = 'ACESFilmic';
 			break;
 
+		case AgXToneMapping:
+			toneMappingName = 'AgX';
+			break;
+
 		case CustomToneMapping:
 			toneMappingName = 'Custom';
 			break;

test/unit/src/constants.tests.js

@@ -71,6 +71,7 @@ export default QUnit.module( 'Constants', () => {
 		assert.equal( Constants.CineonToneMapping, 3, 'CineonToneMapping is equal to 3' );
 		assert.equal( Constants.ACESFilmicToneMapping, 4, 'ACESFilmicToneMapping is equal to 4' );
 		assert.equal( Constants.CustomToneMapping, 5, 'CustomToneMapping is equal to 5' );
+		assert.equal( Constants.AgXToneMapping, 6, 'AgXToneMapping is equal to 6' );
 
 		assert.equal( Constants.AttachedBindMode, 'attached', 'AttachedBindMode is equal to attached' );
 		assert.equal( Constants.DetachedBindMode, 'detached', 'DetachedBindMode is equal to detached' );