text: // deno-fmt-ignore-file
  /// <reference lib="dom" />
  // Copyright 2020 Brandon Jones
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  import { GPUIndexFormat, GPUFilterMode, GPUPrimitiveTopology } from './constants.js';
  
  // ported from https://github.com/toji/web-texture-tool/blob/master/src/webgpu-mipmap-generator.js
  
  class WebGPUTextureUtils {
  
  	constructor( device, glslang ) {
  
  		this.device = device;
  
  		const mipmapVertexSource = `#version 450
  			const vec2 pos[4] = vec2[4](vec2(-1.0f, 1.0f), vec2(1.0f, 1.0f), vec2(-1.0f, -1.0f), vec2(1.0f, -1.0f));
  			const vec2 tex[4] = vec2[4](vec2(0.0f, 0.0f), vec2(1.0f, 0.0f), vec2(0.0f, 1.0f), vec2(1.0f, 1.0f));
  			layout(location = 0) out vec2 vTex;
  			void main() {
  				vTex = tex[gl_VertexIndex];
  				gl_Position = vec4(pos[gl_VertexIndex], 0.0, 1.0);
  			}
  		`;
  
  		const mipmapFragmentSource = `#version 450
  			layout(set = 0, binding = 0) uniform sampler imgSampler;
  			layout(set = 0, binding = 1) uniform texture2D img;
  			layout(location = 0) in vec2 vTex;
  			layout(location = 0) out vec4 outColor;
  			void main() {
  				outColor = texture(sampler2D(img, imgSampler), vTex);
  			}`;
  
  		this.sampler = device.createSampler( { minFilter: GPUFilterMode.Linear } );
  
  		// We'll need a new pipeline for every texture format used.
  		this.pipelines = {};
  
  		this.mipmapVertexShaderModule = device.createShaderModule( {
  			 code: glslang.compileGLSL( mipmapVertexSource, 'vertex' ),
  		 } );
  		 this.mipmapFragmentShaderModule = device.createShaderModule( {
  			 code: glslang.compileGLSL( mipmapFragmentSource, 'fragment' ),
  		 } );
  
  	}
  
  	getMipmapPipeline( format ) {
  
  		let pipeline = this.pipelines[ format ];
  
  		if ( pipeline === undefined ) {
  
  			pipeline = this.device.createRenderPipeline( {
  				vertexStage: {
  					module: this.mipmapVertexShaderModule,
  					entryPoint: 'main',
  				},
  				fragmentStage: {
  					module: this.mipmapFragmentShaderModule,
  					entryPoint: 'main',
  				},
  				primitiveTopology: GPUPrimitiveTopology.TriangleStrip,
  				vertexState: {
  					indexFormat: GPUIndexFormat.Uint32
  				},
  				colorStates: [ { format } ],
  			} );
  			this.pipelines[ format ] = pipeline;
  
  		}
  
  		return pipeline;
  
  	}
  
  	generateMipmaps( textureGPU, textureGPUDescriptor ) {
  
  		const pipeline = this.getMipmapPipeline( textureGPUDescriptor.format );
  
  		const commandEncoder = this.device.createCommandEncoder( {} );
  		const bindGroupLayout = pipeline.getBindGroupLayout( 0 ); // @TODO: Consider making this static.
  
  		let srcView = textureGPU.createView( {
  			baseMipLevel: 0,
  			mipLevelCount: 1,
  		} );
  
  		for ( let i = 1; i < textureGPUDescriptor.mipLevelCount; i ++ ) {
  
  			const dstView = textureGPU.createView( {
  				baseMipLevel: i,
  				mipLevelCount: 1,
  			} );
  
  			const passEncoder = commandEncoder.beginRenderPass( {
  				colorAttachments: [ {
  					attachment: dstView,
  					loadValue: [ 0, 0, 0, 0 ],
  				} ],
  			} );
  
  			const bindGroup = this.device.createBindGroup( {
  				layout: bindGroupLayout,
  				entries: [ {
  					binding: 0,
  					resource: this.sampler,
  				}, {
  					binding: 1,
  					resource: srcView,
  				} ],
  			} );
  
  			passEncoder.setPipeline( pipeline );
  			passEncoder.setBindGroup( 0, bindGroup );
  			passEncoder.draw( 4, 1, 0, 0 );
  			passEncoder.endPass();
  
  			srcView = dstView;
  
  		}
  
  		this.device.defaultQueue.submit( [ commandEncoder.finish() ] );
  
  	}
  
  }
  
  export default WebGPUTextureUtils;
  