playcanvas/build/playcanvas/src/scene/shader-lib/wgsl/chunks/render-pass/frag/volumetricFog.js

Open-source WebGL/WebGPU 3D engine for the web

var volumetricFog_default = `
	#include "screenDepthPS"
	varying uv0: vec2f;
	uniform uFogCameraPos: vec3f;
	uniform uFogCameraFwd: vec3f;
	uniform uFogInvView: mat4x4f;
	uniform uFogProjScale: vec2f;
	uniform uFogTint: vec3f;
	uniform uFogLightColor: vec3f;
	uniform uFogLightDir: vec3f;
	uniform uFogAmbient: vec3f;
	uniform uFogParams: vec4f;
	uniform uFogScatterParams: vec4f;
	#ifdef FOG_SHADOWS
		uniform uFogShadowMatrixPalette: array<mat4x4f, 4>;
		uniform uFogShadowCascadeDistances: vec4f;
		uniform uFogShadowParams: vec4f;
		#ifdef FOG_SHADOW_PCF
			var uFogShadowMap: texture_depth_2d;
			var uFogShadowMapSampler: sampler_comparison;
		#else
			var uFogShadowMap: texture_2d<f32>;
			var uFogShadowMapSampler: sampler;
		#endif
		fn sampleFogShadow(worldPos: vec3f, viewDepth: f32) -> f32 {
			if (viewDepth >= uniform.uFogShadowParams.w) {
				return 1.0;
			}
			let comparisons: vec4f = step(uniform.uFogShadowCascadeDistances, vec4f(viewDepth));
			let cascadeIndex: i32 = i32(min(dot(comparisons, vec4f(1.0)), uniform.uFogShadowParams.x - 1.0));
			let shadowCoord: vec3f = (uniform.uFogShadowMatrixPalette[cascadeIndex] * vec4f(worldPos, 1.0)).xyz;
			let z: f32 = shadowCoord.z - uniform.uFogShadowParams.y;
			#ifdef FOG_SHADOW_PCF
				return textureSampleCompareLevel(uFogShadowMap, uFogShadowMapSampler, shadowCoord.xy, z);
			#else
				return step(z, textureSampleLevel(uFogShadowMap, uFogShadowMapSampler, shadowCoord.xy, 0.0).r);
			#endif
		}
	#endif
	fn fogNoise(fragCoord: vec2f) -> f32 {
		const magic: vec3f = vec3f(0.06711056, 0.00583715, 52.9829189);
		return fract(magic.z * fract(dot(fragCoord, magic.xy)));
	}
	fn fogPhase(cosTheta: f32, g: f32) -> f32 {
		let g2: f32 = g * g;
		let denom: f32 = 1.0 + g2 - 2.0 * g * cosTheta;
		return (1.0 - g2) / (12.56637 * denom * sqrt(denom));
	}
	@fragment
	fn fragmentMain(input: FragmentInput) -> FragmentOutput {
		var output: FragmentOutput;
		let ndcUV: vec2f = vec2f(input.uv0.x, 1.0 - input.uv0.y);
		let ndc: vec2f = ndcUV * 2.0 - 1.0;
		let rayDir: vec3f = normalize((uniform.uFogInvView * vec4f(ndc * uniform.uFogProjScale, -1.0, 0.0)).xyz);
		let rayDot: f32 = max(dot(rayDir, uniform.uFogCameraFwd), 0.001);
		let rayLength: f32 = min(getLinearScreenDepth(input.uv0) / rayDot, uniform.uFogParams.w);
		let stepCount: f32 = uniform.uFogScatterParams.y;
		let dt: f32 = rayLength / stepCount;
		let noise: f32 = fract(fogNoise(pcPosition.xy) + uniform.uFogScatterParams.z);
		let sunLight: vec3f = uniform.uFogLightColor * fogPhase(dot(rayDir, uniform.uFogLightDir), uniform.uFogScatterParams.x);
		var inscatter: vec3f = vec3f(0.0);
		var transmittance: f32 = 1.0;
		for (var i: f32 = 0.0; i < stepCount; i += 1.0) {
			let t: f32 = (i + noise) * dt;
			let pos: vec3f = uniform.uFogCameraPos + rayDir * t;
			let density: f32 = uniform.uFogParams.x * exp(-uniform.uFogParams.z * max(pos.y - uniform.uFogParams.y, 0.0));
			var shadow: f32 = 1.0;
			#ifdef FOG_SHADOWS
				shadow = mix(1.0, sampleFogShadow(pos, t * rayDot), uniform.uFogScatterParams.w);
			#endif
			let radiance: vec3f = sunLight * shadow + uniform.uFogAmbient;
			inscatter += transmittance * uniform.uFogTint * radiance * (density * dt);
			transmittance *= exp(-density * dt);
			if (transmittance < 0.005) {
				break;
			}
		}
		output.color = vec4f(inscatter, transmittance);
		return output;
	}
`;
export {
	volumetricFog_default as default
};