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November 27, 2025 15:32
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WebGPU: SetScissorRect with storage texture
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| html, body { margin: 0; height: 100% } | |
| canvas { width: 100%; height: 100%; display: block; } | |
| #fail { | |
| position: fixed; | |
| left: 0; | |
| top: 0; | |
| width: 100%; | |
| height: 100%; | |
| display: flex; | |
| justify-content: center; | |
| align-items: center; | |
| background: red; | |
| color: white; | |
| font-weight: bold; | |
| font-family: monospace; | |
| font-size: 16pt; | |
| text-align: center; | |
| } |
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| /*bug-in-github-api-content-can-not-be-empty*/ |
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| // WebGPU Cube | |
| /* global GPUBufferUsage */ | |
| /* global GPUTextureUsage */ | |
| import {vec3, mat4} from 'https://webgpufundamentals.org/3rdparty/wgpu-matrix.module.js'; | |
| async function main() { | |
| const adapter = await navigator.gpu?.requestAdapter(); | |
| const device = await adapter?.requestDevice(); | |
| if (!device) { | |
| fail('need webgpu'); | |
| return; | |
| } | |
| const shaderSrc = ` | |
| @vertex | |
| fn myVSMain(@builtin(vertex_index) vNdx: u32) -> @builtin(position) vec4f { | |
| let pos = array( | |
| vec2f(-1, 3), | |
| vec2f( 3, -1), | |
| vec2f(-1, -1), | |
| ); | |
| return vec4f(pos[vNdx], 0, 1); | |
| } | |
| @group(0) @binding(0) var tex: texture_storage_2d<rgba8unorm, write>; | |
| @fragment | |
| fn myFSMain(@builtin(position) pos: vec4f) -> @location(0) vec4f { | |
| let t = vec2u(pos.xy); | |
| textureStore(tex, t, (pos + 0.5) * (1.0 / 255.0)); | |
| return vec4f(1,0,0,1); | |
| } | |
| `; | |
| const shaderModule = device.createShaderModule({code: shaderSrc}); | |
| const tex = device.createTexture({ | |
| size: [2, 2, 1], | |
| format: 'rgba8unorm', | |
| usage: | |
| GPUTextureUsage.STORAGE_BINDING | | |
| GPUTextureUsage.COPY_SRC, | |
| }); | |
| const destTex = device.createTexture({ | |
| size: [2, 2, 1], | |
| format: 'rgba8unorm', | |
| usage: | |
| GPUTextureUsage.RENDER_ATTACHMENT, | |
| }); | |
| const pipeline = device.createRenderPipeline({ | |
| layout: 'auto', | |
| vertex: { | |
| module: shaderModule, | |
| }, | |
| fragment: { | |
| module: shaderModule, | |
| targets: [ | |
| {format: 'rgba8unorm'}, | |
| ], | |
| }, | |
| }); | |
| const bindGroup = device.createBindGroup({ | |
| layout: pipeline.getBindGroupLayout(0), | |
| entries: [ | |
| { binding: 0, resource: tex.createView() }, | |
| ], | |
| }); | |
| const renderPassDescriptor = { | |
| colorAttachments: [ | |
| { | |
| view: destTex.createView(), | |
| loadOp: 'clear', | |
| storeOp: 'store', | |
| }, | |
| ], | |
| }; | |
| const encoder = device.createCommandEncoder(); | |
| const pass = encoder.beginRenderPass(renderPassDescriptor); | |
| pass.setPipeline(pipeline); | |
| pass.setBindGroup(0, bindGroup); | |
| pass.setScissorRect(0,0,1,1); | |
| pass.draw(3); | |
| pass.end(); | |
| const resultBuffer = device.createBuffer({ | |
| size: 256 * 2, | |
| usage: GPUBufferUsage.COPY_DST | GPUBufferUsage.MAP_READ, | |
| }); | |
| encoder.copyTextureToBuffer( | |
| { texture: tex }, | |
| { buffer: resultBuffer, bytesPerRow: 256 }, | |
| [2, 2], | |
| ); | |
| device.queue.submit([encoder.finish()]); | |
| await resultBuffer.mapAsync(GPUMapMode.READ); | |
| const pix = view => [...view].map(v => v.toString(16).padStart(2, '0')).join(' '); | |
| const result = new Uint8Array(resultBuffer.getMappedRange()); | |
| for (let y = 0; y < tex.height; ++y) { | |
| for (let x = 0; x < tex.width; ++x) { | |
| const off = y * 256 + x * 4; | |
| console.log(`${x},${y}: ${pix(result.subarray(off, off + 4))}`); | |
| } | |
| } | |
| } | |
| main(); | |
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| {"name":"WebGPU: SetScissorRect with storage texture","settings":{},"filenames":["index.html","index.css","index.js"]} |
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