src/webgpu/api/operation/sampling/sampler_texture.spec.ts - external/github.com/gpuweb/cts - Git at Google

 export const description = `
 Tests samplers with textures.

 - test that you can use the maximum number of textures
   with the maximum number of samplers.
 `;

 import { makeTestGroup } from '../../../../common/framework/test_group.js';
 import { assert, range } from '../../../../common/util/util.js';
 import { AllFeaturesMaxLimitsGPUTest } from '../../../gpu_test.js';
 import * as ttu from '../../../texture_test_utils.js';
 import { TexelView } from '../../../util/texture/texel_view.js';

 export const g = makeTestGroup(AllFeaturesMaxLimitsGPUTest);

 g.test('sample_texture_combos')
   .desc(
     `
 Test that you can use the maximum number of textures with the maximum number of samplers.
 and the maximum number of storage textures.

 The test works by making the maximum number of texture+sampler combos and the max storage
 textures per stage. Each texture is [maxSamplersPerShaderStage + maxStorageTexturesInStage, 1]
 in size and each texel is [textureId, samplerId]. A function "useCombo<StageNum>(comboId)" is
 made that returns stage[stageNum].combo[comboId].texel[id, 0] or to put it another way, it
 returns the nth texel from the nth combo for that stage.

 These are read in both the vertex shader and fragment shader and written to a
 [maxSamplerPerShaderStage + maxStorageTexturesInStage, 2] texture where the top row is the
 values from the vertex shader and the bottom row from the fragment shader.

 The result should be a texture that has a value in each texel unique to a particular combo
 or storage texture.
 `
   )
   .fn(t => {
     const { device } = t;
     const {
       maxSampledTexturesPerShaderStage,
       maxSamplersPerShaderStage,
       maxBindingsPerBindGroup,
       maxStorageTexturesInVertexStage,
       maxStorageTexturesInFragmentStage,
       maxStorageTexturesPerShaderStage,
     } = device.limits;

     assert(maxSampledTexturesPerShaderStage < 0xfffe);
     assert(maxSamplersPerShaderStage < 0xfffe);

     const numStorageTexturesInVertexStage =
       maxStorageTexturesInVertexStage ?? maxStorageTexturesPerShaderStage;
     const numStorageTexturesInFragmentStage =
       maxStorageTexturesInFragmentStage ?? maxStorageTexturesPerShaderStage;

     const maxTestableCombosPerStage = t.isCompatibility
       ? Math.min(maxSampledTexturesPerShaderStage, maxSamplersPerShaderStage)
       : maxSampledTexturesPerShaderStage * maxSamplersPerShaderStage;

     const textures: GPUTexture[] = [];
     const declarationLines: string[] = [];
     const groups: GPUBindGroupEntry[][] = [[]];
     const layouts: GPUBindGroupLayoutEntry[][] = [[]];
     const textureIdToTexelValue = new Map<string, number>();
     const samplerIds = new Set<string>();
     // per stage, per texel, each texel has 2 numbers, the texture id, and sampler id
     const expected: number[][][] = [[], []];

     function addResource(
       stage: number,
       resourceId: string,
       resource: GPUTextureView | GPUSampler,
       storageTexture?: boolean
     ) {
       let bindGroupEntries = groups[groups.length - 1];
       let bindGroupLayoutEntries = layouts[groups.length - 1];
       if (bindGroupEntries.length === maxBindingsPerBindGroup) {
         bindGroupEntries = [];
         bindGroupLayoutEntries = [];
         groups.push(bindGroupEntries);
         layouts.push(bindGroupLayoutEntries);
       }
       const resourceType =
         resource instanceof GPUSampler
           ? 'sampler'
           : storageTexture
           ? 'texture_storage_2d<rgba8unorm, read>'
           : 'texture_2d<f32>';
       const binding = bindGroupEntries.length;
       declarationLines.push(
         `    @group(${groups.length - 1}) @binding(${binding}) var ${resourceId}: ${resourceType};`
       );
       bindGroupEntries.push({
         binding,
         resource,
       });
       bindGroupLayoutEntries.push({
         binding,
         visibility: stage === 0 ? GPUShaderStage.VERTEX : GPUShaderStage.FRAGMENT,
         ...(resource instanceof GPUSampler
           ? {
               sampler: {},
             }
           : storageTexture
           ? {
               storageTexture: {
                 access: 'read-only',
                 format: 'rgba8unorm',
               },
             }
           : {
               texture: {},
             }),
       });
     }

     const width =
       maxSamplersPerShaderStage +
       Math.max(numStorageTexturesInVertexStage, numStorageTexturesInFragmentStage);
     t.debug(`width: ${width}`);

     function addTexture(stage: number, textureNum: number, storageTexture: boolean) {
       const textureId = `tex${stage}_${textureNum}`;
       let texelValue = textureIdToTexelValue.get(textureId);
       if (texelValue === undefined) {
         texelValue = textures.length + 1;
         textureIdToTexelValue.set(textureId, texelValue);
         const texture = t.createTextureTracked({
           format: 'rgba8unorm',
           size: [width, 1],
           usage:
             GPUTextureUsage.STORAGE_BINDING |
             GPUTextureUsage.TEXTURE_BINDING |
             GPUTextureUsage.COPY_DST,
         });
         textures.push(texture);
         // Encode an rgba8unorm texture with rg16uint data where each texel is
         // [texelValue | (stage << 15), {samplerId + 1}]
         // The +1 is to avoid 0.
         const data = new Uint16Array(width * 2);
         const rg = texelValue | (stage << 15);
         for (let x = 0; x < width; ++x) {
           const offset = x * 2;
           const samplerNum = (x % maxSamplersPerShaderStage) + 1;
           data[offset + 0] = rg;
           data[offset + 1] = storageTexture ? 0 : samplerNum;
         }
         device.queue.writeTexture({ texture }, data, {}, [width]);
         addResource(stage, textureId, texture.createView(), storageTexture);
       }
       return { textureId, texelValue };
     }

     const kAddressModes = ['repeat', 'clamp-to-edge', 'mirror-repeat'] as const;
     const getAddressMode = (hash: number, depth: number) => {
       return kAddressModes[
         ((hash / Math.pow(kAddressModes.length, depth)) | 0) % kAddressModes.length
       ];
     };

     function addSampler(stage: number, samplerNum: number) {
       const samplerId = `smp${stage}_${samplerNum}`;
       if (!samplerIds.has(samplerId)) {
         const samplerNum = samplerIds.size;
         samplerIds.add(samplerId);
         // try to make each sampler unique. This is because some backends
         // coalesce samplers with the same settings.
         const addressHash = samplerNum >> 3;
         const sampler = device.createSampler({
           minFilter: samplerNum & 1 ? 'linear' : 'nearest',
           magFilter: samplerNum & 2 ? 'linear' : 'nearest',
           mipmapFilter: samplerNum & 4 ? 'linear' : 'nearest',
           addressModeU: getAddressMode(addressHash, 0),
           addressModeV: getAddressMode(addressHash, 1),
           addressModeW: getAddressMode(addressHash, 2),
         });
         addResource(stage, samplerId, sampler);
       }
       return samplerId;
     }

     const numStorageTexturesInStage = [
       numStorageTexturesInVertexStage,
       numStorageTexturesInFragmentStage,
     ];

     // Note: We are storing textureId, samplerId in the texture. That suggests we could use rgba32uint
     // texture but we can't do that because we want to be able to set the samplers to linear.
     // Similarly we can't use rgba32float since they're not filterable by default.
     // So, we encode via rgba8unorm where rg is a 16bit textureId and ba is a 16bit samplerId
     const code = `
     // maxTestableCombosPerStage: ${maxTestableCombosPerStage}
     // numStorageTexturesPerVertexStage: ${numStorageTexturesInVertexStage}
     // numStorageTexturesPerFragmentStage: ${numStorageTexturesInFragmentStage}

     fn sample(t: texture_2d<f32>, s: sampler, validId: u32, currentId: u32, c: vec4f) -> vec4f {
       let size = textureDimensions(t, 0);
       let uv = vec2f((f32(currentId % ${maxSamplersPerShaderStage}) + 0.5) / f32(size.x), 0.5);
       let v = textureSampleLevel(t, s, uv, 0);
       return select(c, v, currentId == validId);
     }

     fn load(t: texture_storage_2d<rgba8unorm, read>, validId: u32, currentId: u32, c: vec4f) -> vec4f {
       let size = textureDimensions(t);
       let uv = vec2u(currentId % size.x, 0);
       let v = textureLoad(t, uv);
       return select(c, v, currentId == validId);
     }

     ${range(
       2,
       stage => `
       fn useCombos${stage}(id: u32) -> vec4f {
         var c: vec4f;
 ${range(maxTestableCombosPerStage, i => {
   const texNum = (i / maxSamplersPerShaderStage) | 0;
   const { textureId, texelValue } = addTexture(stage, texNum, false);
   const smpNum = i % maxSamplersPerShaderStage;
   const samplerId = addSampler(stage, smpNum);
   expected[stage].push([texelValue | (stage << 15), smpNum + 1]);
   return `        c = sample(${textureId}, ${samplerId}, ${i}, id, c);`;
 }).join('\n')}
 ${range(numStorageTexturesInStage[stage], i => {
   const texNum = textures.length;
   const { textureId, texelValue } = addTexture(stage, texNum, true);
   expected[stage].push([texelValue | (stage << 15), 0]);
   return `        c = load(${textureId}, ${i + maxTestableCombosPerStage}, id, c);`;
 }).join('\n')}
         return c;
       }
     `
     ).join('\n\n')}

 ${declarationLines.join('\n')}

     struct VOut {
       @builtin(position) pos: vec4f,
       @location(0) value: vec4f,
     };

     @vertex fn vs(@builtin(instance_index) iNdx: u32) -> VOut {
       return VOut(
         vec4f(0, 0, 0, 1),
         useCombos0(iNdx),
       );
     }

     @fragment fn fs(vin: VOut) -> @location(0) vec4u {
       let ndx = u32(vin.pos.x);
       let f = select(vin.value, useCombos1(ndx), vin.pos.y > 1.0);

       // We're putting two u16 values in the source data but as rgba8unorm.
       // Convert them back to u32 then split them back into two u16s
       let bytes = pack4x8unorm(f);
       return vec4u(bytes & 0xffff, bytes >> 16, 0, 0);
     }
     `;

     t.debug(code);

     const module = device.createShaderModule({ code });
     const bindGroupLayouts = layouts.map(entries => device.createBindGroupLayout({ entries }));

     const pipeline = device.createRenderPipeline({
       layout: device.createPipelineLayout({ bindGroupLayouts }),
       vertex: {
         module,
       },
       fragment: {
         module,
         targets: [{ format: 'rg16uint' }],
       },
       primitive: { topology: 'point-list' },
     });

     const bindGroups = groups.map((entries, i) =>
       device.createBindGroup({
         layout: pipeline.getBindGroupLayout(i),
         entries,
       })
     );

     const numAcross =
       maxTestableCombosPerStage +
       numStorageTexturesInVertexStage +
       numStorageTexturesInFragmentStage;

     const renderTarget = t.createTextureTracked({
       format: 'rg16uint',
       size: [numAcross, 2],
       usage: GPUTextureUsage.RENDER_ATTACHMENT | GPUTextureUsage.COPY_SRC,
     });
     textures.push(renderTarget);

     const encoder = device.createCommandEncoder();
     const pass = encoder.beginRenderPass({
       colorAttachments: [
         {
           view: renderTarget.createView(),
           loadOp: 'clear',
           storeOp: 'store',
         },
       ],
     });
     pass.setPipeline(pipeline);
     bindGroups.forEach((bindGroup, i) => pass.setBindGroup(i, bindGroup));
     for (let y = 0; y < 2; ++y) {
       for (let x = 0; x < numAcross; ++x) {
         pass.setViewport(x, y, 1, 1, 0, 1);
         pass.draw(1, 1, 0, x);
       }
     }
     pass.end();

     device.queue.submit([encoder.finish()]);

     const expectedData = new Uint16Array(numAcross * 2 * 2);
     for (let stage = 0; stage < 2; ++stage) {
       expected[stage].forEach(([tid, sid], i) => {
         const offset = (numAcross * stage + i) * 2;
         expectedData[offset + 0] = tid;
         expectedData[offset + 1] = sid;
       });
     }

     const expTexelView = TexelView.fromTextureDataByReference(
       'rg16uint',
       new Uint8Array(expectedData.buffer),
       {
         bytesPerRow: numAcross * 4,
         rowsPerImage: 2,
         subrectOrigin: [0, 0, 0],
         subrectSize: [numAcross, 2],
       }
     );

     const size = [numAcross, 2];
     ttu.expectTexelViewComparisonIsOkInTexture(t, { texture: renderTarget }, expTexelView, size);

     textures.forEach(texture => texture.destroy());
   });
	export const description = `
	Tests samplers with textures.

	- test that you can use the maximum number of textures
	with the maximum number of samplers.
	`;

	import { makeTestGroup } from '../../../../common/framework/test_group.js';
	import { assert, range } from '../../../../common/util/util.js';
	import { AllFeaturesMaxLimitsGPUTest } from '../../../gpu_test.js';
	import * as ttu from '../../../texture_test_utils.js';
	import { TexelView } from '../../../util/texture/texel_view.js';

	export const g = makeTestGroup(AllFeaturesMaxLimitsGPUTest);

	g.test('sample_texture_combos')
	.desc(
	`
	Test that you can use the maximum number of textures with the maximum number of samplers.
	and the maximum number of storage textures.

	The test works by making the maximum number of texture+sampler combos and the max storage
	textures per stage. Each texture is [maxSamplersPerShaderStage + maxStorageTexturesInStage, 1]
	in size and each texel is [textureId, samplerId]. A function "useCombo<StageNum>(comboId)" is
	made that returns stage[stageNum].combo[comboId].texel[id, 0] or to put it another way, it
	returns the nth texel from the nth combo for that stage.

	These are read in both the vertex shader and fragment shader and written to a
	[maxSamplerPerShaderStage + maxStorageTexturesInStage, 2] texture where the top row is the
	values from the vertex shader and the bottom row from the fragment shader.

	The result should be a texture that has a value in each texel unique to a particular combo
	or storage texture.
	`
	)
	.fn(t => {
	const { device } = t;
	const {
	maxSampledTexturesPerShaderStage,
	maxSamplersPerShaderStage,
	maxBindingsPerBindGroup,
	maxStorageTexturesInVertexStage,
	maxStorageTexturesInFragmentStage,
	maxStorageTexturesPerShaderStage,
	} = device.limits;

	assert(maxSampledTexturesPerShaderStage < 0xfffe);
	assert(maxSamplersPerShaderStage < 0xfffe);

	const numStorageTexturesInVertexStage =
	maxStorageTexturesInVertexStage ?? maxStorageTexturesPerShaderStage;
	const numStorageTexturesInFragmentStage =
	maxStorageTexturesInFragmentStage ?? maxStorageTexturesPerShaderStage;

	const maxTestableCombosPerStage = t.isCompatibility
	? Math.min(maxSampledTexturesPerShaderStage, maxSamplersPerShaderStage)
	: maxSampledTexturesPerShaderStage * maxSamplersPerShaderStage;

	const textures: GPUTexture[] = [];
	const declarationLines: string[] = [];
	const groups: GPUBindGroupEntry[][] = [[]];
	const layouts: GPUBindGroupLayoutEntry[][] = [[]];
	const textureIdToTexelValue = new Map<string, number>();
	const samplerIds = new Set<string>();
	// per stage, per texel, each texel has 2 numbers, the texture id, and sampler id
	const expected: number[][][] = [[], []];

	function addResource(
	stage: number,
	resourceId: string,
	resource: GPUTextureView \| GPUSampler,
	storageTexture?: boolean
	) {
	let bindGroupEntries = groups[groups.length - 1];
	let bindGroupLayoutEntries = layouts[groups.length - 1];
	if (bindGroupEntries.length === maxBindingsPerBindGroup) {
	bindGroupEntries = [];
	bindGroupLayoutEntries = [];
	groups.push(bindGroupEntries);
	layouts.push(bindGroupLayoutEntries);
	}
	const resourceType =
	resource instanceof GPUSampler
	? 'sampler'
	: storageTexture
	? 'texture_storage_2d<rgba8unorm, read>'
	: 'texture_2d<f32>';
	const binding = bindGroupEntries.length;
	declarationLines.push(
	` @group(${groups.length - 1}) @binding(${binding}) var ${resourceId}: ${resourceType};`
	);
	bindGroupEntries.push({
	binding,
	resource,
	});
	bindGroupLayoutEntries.push({
	binding,
	visibility: stage === 0 ? GPUShaderStage.VERTEX : GPUShaderStage.FRAGMENT,
	...(resource instanceof GPUSampler
	? {
	sampler: {},
	}
	: storageTexture
	? {
	storageTexture: {
	access: 'read-only',
	format: 'rgba8unorm',
	},
	}
	: {
	texture: {},
	}),
	});
	}

	const width =
	maxSamplersPerShaderStage +
	Math.max(numStorageTexturesInVertexStage, numStorageTexturesInFragmentStage);
	t.debug(`width: ${width}`);

	function addTexture(stage: number, textureNum: number, storageTexture: boolean) {
	const textureId = `tex${stage}_${textureNum}`;
	let texelValue = textureIdToTexelValue.get(textureId);
	if (texelValue === undefined) {
	texelValue = textures.length + 1;
	textureIdToTexelValue.set(textureId, texelValue);
	const texture = t.createTextureTracked({
	format: 'rgba8unorm',
	size: [width, 1],
	usage:
	GPUTextureUsage.STORAGE_BINDING \|
	GPUTextureUsage.TEXTURE_BINDING \|
	GPUTextureUsage.COPY_DST,
	});
	textures.push(texture);
	// Encode an rgba8unorm texture with rg16uint data where each texel is
	// [texelValue \| (stage << 15), {samplerId + 1}]
	// The +1 is to avoid 0.
	const data = new Uint16Array(width * 2);
	const rg = texelValue \| (stage << 15);
	for (let x = 0; x < width; ++x) {
	const offset = x * 2;
	const samplerNum = (x % maxSamplersPerShaderStage) + 1;
	data[offset + 0] = rg;
	data[offset + 1] = storageTexture ? 0 : samplerNum;
	}
	device.queue.writeTexture({ texture }, data, {}, [width]);
	addResource(stage, textureId, texture.createView(), storageTexture);
	}
	return { textureId, texelValue };
	}

	const kAddressModes = ['repeat', 'clamp-to-edge', 'mirror-repeat'] as const;
	const getAddressMode = (hash: number, depth: number) => {
	return kAddressModes[
	((hash / Math.pow(kAddressModes.length, depth)) \| 0) % kAddressModes.length
	];
	};

	function addSampler(stage: number, samplerNum: number) {
	const samplerId = `smp${stage}_${samplerNum}`;
	if (!samplerIds.has(samplerId)) {
	const samplerNum = samplerIds.size;
	samplerIds.add(samplerId);
	// try to make each sampler unique. This is because some backends
	// coalesce samplers with the same settings.
	const addressHash = samplerNum >> 3;
	const sampler = device.createSampler({
	minFilter: samplerNum & 1 ? 'linear' : 'nearest',
	magFilter: samplerNum & 2 ? 'linear' : 'nearest',
	mipmapFilter: samplerNum & 4 ? 'linear' : 'nearest',
	addressModeU: getAddressMode(addressHash, 0),
	addressModeV: getAddressMode(addressHash, 1),
	addressModeW: getAddressMode(addressHash, 2),
	});
	addResource(stage, samplerId, sampler);
	}
	return samplerId;
	}

	const numStorageTexturesInStage = [
	numStorageTexturesInVertexStage,
	numStorageTexturesInFragmentStage,
	];

	// Note: We are storing textureId, samplerId in the texture. That suggests we could use rgba32uint
	// texture but we can't do that because we want to be able to set the samplers to linear.
	// Similarly we can't use rgba32float since they're not filterable by default.
	// So, we encode via rgba8unorm where rg is a 16bit textureId and ba is a 16bit samplerId
	const code = `
	// maxTestableCombosPerStage: ${maxTestableCombosPerStage}
	// numStorageTexturesPerVertexStage: ${numStorageTexturesInVertexStage}
	// numStorageTexturesPerFragmentStage: ${numStorageTexturesInFragmentStage}

	fn sample(t: texture_2d<f32>, s: sampler, validId: u32, currentId: u32, c: vec4f) -> vec4f {
	let size = textureDimensions(t, 0);
	let uv = vec2f((f32(currentId % ${maxSamplersPerShaderStage}) + 0.5) / f32(size.x), 0.5);
	let v = textureSampleLevel(t, s, uv, 0);
	return select(c, v, currentId == validId);
	}

	fn load(t: texture_storage_2d<rgba8unorm, read>, validId: u32, currentId: u32, c: vec4f) -> vec4f {
	let size = textureDimensions(t);
	let uv = vec2u(currentId % size.x, 0);
	let v = textureLoad(t, uv);
	return select(c, v, currentId == validId);
	}

	${range(
	2,
	stage => `
	fn useCombos${stage}(id: u32) -> vec4f {
	var c: vec4f;
	${range(maxTestableCombosPerStage, i => {
	const texNum = (i / maxSamplersPerShaderStage) \| 0;
	const { textureId, texelValue } = addTexture(stage, texNum, false);
	const smpNum = i % maxSamplersPerShaderStage;
	const samplerId = addSampler(stage, smpNum);
	expected[stage].push([texelValue \| (stage << 15), smpNum + 1]);
	return ` c = sample(${textureId}, ${samplerId}, ${i}, id, c);`;
	}).join('\n')}
	${range(numStorageTexturesInStage[stage], i => {
	const texNum = textures.length;
	const { textureId, texelValue } = addTexture(stage, texNum, true);
	expected[stage].push([texelValue \| (stage << 15), 0]);
	return ` c = load(${textureId}, ${i + maxTestableCombosPerStage}, id, c);`;
	}).join('\n')}
	return c;
	}
	`
	).join('\n\n')}

	${declarationLines.join('\n')}

	struct VOut {
	@builtin(position) pos: vec4f,
	@location(0) value: vec4f,
	};

	@vertex fn vs(@builtin(instance_index) iNdx: u32) -> VOut {
	return VOut(
	vec4f(0, 0, 0, 1),
	useCombos0(iNdx),
	);
	}

	@fragment fn fs(vin: VOut) -> @location(0) vec4u {
	let ndx = u32(vin.pos.x);
	let f = select(vin.value, useCombos1(ndx), vin.pos.y > 1.0);

	// We're putting two u16 values in the source data but as rgba8unorm.
	// Convert them back to u32 then split them back into two u16s
	let bytes = pack4x8unorm(f);
	return vec4u(bytes & 0xffff, bytes >> 16, 0, 0);
	}
	`;

	t.debug(code);

	const module = device.createShaderModule({ code });
	const bindGroupLayouts = layouts.map(entries => device.createBindGroupLayout({ entries }));

	const pipeline = device.createRenderPipeline({
	layout: device.createPipelineLayout({ bindGroupLayouts }),
	vertex: {
	module,
	},
	fragment: {
	module,
	targets: [{ format: 'rg16uint' }],
	},
	primitive: { topology: 'point-list' },
	});

	const bindGroups = groups.map((entries, i) =>
	device.createBindGroup({
	layout: pipeline.getBindGroupLayout(i),
	entries,
	})
	);

	const numAcross =
	maxTestableCombosPerStage +
	numStorageTexturesInVertexStage +
	numStorageTexturesInFragmentStage;

	const renderTarget = t.createTextureTracked({
	format: 'rg16uint',
	size: [numAcross, 2],
	usage: GPUTextureUsage.RENDER_ATTACHMENT \| GPUTextureUsage.COPY_SRC,
	});
	textures.push(renderTarget);

	const encoder = device.createCommandEncoder();
	const pass = encoder.beginRenderPass({
	colorAttachments: [
	{
	view: renderTarget.createView(),
	loadOp: 'clear',
	storeOp: 'store',
	},
	],
	});
	pass.setPipeline(pipeline);
	bindGroups.forEach((bindGroup, i) => pass.setBindGroup(i, bindGroup));
	for (let y = 0; y < 2; ++y) {
	for (let x = 0; x < numAcross; ++x) {
	pass.setViewport(x, y, 1, 1, 0, 1);
	pass.draw(1, 1, 0, x);
	}
	}
	pass.end();

	device.queue.submit([encoder.finish()]);

	const expectedData = new Uint16Array(numAcross * 2 * 2);
	for (let stage = 0; stage < 2; ++stage) {
	expected[stage].forEach(([tid, sid], i) => {
	const offset = (numAcross * stage + i) * 2;
	expectedData[offset + 0] = tid;
	expectedData[offset + 1] = sid;
	});
	}

	const expTexelView = TexelView.fromTextureDataByReference(
	'rg16uint',
	new Uint8Array(expectedData.buffer),
	{
	bytesPerRow: numAcross * 4,
	rowsPerImage: 2,
	subrectOrigin: [0, 0, 0],
	subrectSize: [numAcross, 2],
	}
	);

	const size = [numAcross, 2];
	ttu.expectTexelViewComparisonIsOkInTexture(t, { texture: renderTarget }, expTexelView, size);

	textures.forEach(texture => texture.destroy());
	});