playcanvas/build/playcanvas/src/extras/render-passes/render-pass-downsample.js

PlayCanvas WebGL game engine

import { SHADERLANGUAGE_GLSL, SHADERLANGUAGE_WGSL, SEMANTIC_POSITION } from '../../platform/graphics/constants.js';
import { RenderPassShaderQuad } from '../../scene/graphics/render-pass-shader-quad.js';
import { ShaderUtils } from '../../scene/shader-lib/shader-utils.js';
import glslDownsamplePS from '../../scene/shader-lib/glsl/chunks/render-pass/frag/downsample.js';
import wgslDownsamplePS from '../../scene/shader-lib/wgsl/chunks/render-pass/frag/downsample.js';
import { ShaderChunks } from '../../scene/shader-lib/shader-chunks.js';

class RenderPassDownsample extends RenderPassShaderQuad {
		constructor(device, sourceTexture, options = {}){
				super(device);
				this.sourceTexture = sourceTexture;
				this.premultiplyTexture = options.premultiplyTexture;
				ShaderChunks.get(device, SHADERLANGUAGE_GLSL).set('downsamplePS', glslDownsamplePS);
				ShaderChunks.get(device, SHADERLANGUAGE_WGSL).set('downsamplePS', wgslDownsamplePS);
				const boxFilter = options.boxFilter ?? false;
				const key = `${boxFilter ? 'Box' : ''}-${options.premultiplyTexture ? 'Premultiply' : ''}-${options.premultiplySrcChannel ?? ''}-${options.removeInvalid ? 'RemoveInvalid' : ''}`;
				const defines = new Map();
				if (boxFilter) defines.set('BOXFILTER', '');
				if (options.premultiplyTexture) defines.set('PREMULTIPLY', '');
				if (options.removeInvalid) defines.set('REMOVE_INVALID', '');
				defines.set('{PREMULTIPLY_SRC_CHANNEL}', options.premultiplySrcChannel ?? 'x');
				this.shader = ShaderUtils.createShader(device, {
						uniqueName: `DownSampleShader:${key}`,
						attributes: {
								aPosition: SEMANTIC_POSITION
						},
						vertexChunk: 'quadVS',
						fragmentChunk: 'downsamplePS',
						fragmentDefines: defines
				});
				this.sourceTextureId = device.scope.resolve('sourceTexture');
				this.premultiplyTextureId = device.scope.resolve('premultiplyTexture');
				this.sourceInvResolutionId = device.scope.resolve('sourceInvResolution');
				this.sourceInvResolutionValue = new Float32Array(2);
		}
		setSourceTexture(value) {
				this._sourceTexture = value;
				this.options.resizeSource = value;
		}
		execute() {
				this.sourceTextureId.setValue(this.sourceTexture);
				if (this.premultiplyTexture) {
						this.premultiplyTextureId.setValue(this.premultiplyTexture);
				}
				this.sourceInvResolutionValue[0] = 1.0 / this.sourceTexture.width;
				this.sourceInvResolutionValue[1] = 1.0 / this.sourceTexture.height;
				this.sourceInvResolutionId.setValue(this.sourceInvResolutionValue);
				super.execute();
		}
}

export { RenderPassDownsample };