src/webgpu/api/operation/render_pass/resolve.spec.ts

export const description = `API Operation Tests for multisample resolve in render passes.`;

import { makeTestGroup } from '../../../../common/framework/test_group.js';
import { isTextureFormatPossiblyResolvable, kColorTextureFormats } from '../../../format_info.js';
import { AllFeaturesMaxLimitsGPUTest } from '../../../gpu_test.js';
import * as ttu from '../../../texture_test_utils.js';

const kSlotsToResolve = [
  [0, 2],
  [1, 3],
  [0, 1, 2, 3],
];

const kSize = 4;
const kDepthStencilFormat: GPUTextureFormat = 'depth24plus-stencil8';

export const g = makeTestGroup(AllFeaturesMaxLimitsGPUTest);

g.test('render_pass_resolve')
  .desc(
    `
Test basic render pass resolve behavior for combinations of:
  - number of color attachments, some with and some without a resolveTarget
  - {a single draw+resolve pass, one draw-store pass and one empty load-resolve pass}
    (attempts to test known driver bugs with empty resolve passes)
  - in the resolve pass, storeOp set to {'store', 'discard'}
  - mip levels {0, 1} and array layers {0, 1}
    TODO: cases where color attachment and resolve target don't have the same mip level
  - resolveTarget {2d array layer, TODO: 3d slice} {0, >0} with {2d, TODO: 3d} resolveTarget
    TODO: cases where color attachment and resolve target don't have the same z (slice or layer)
  - TODO: test that any not-resolved attachments are rendered to correctly.
  - TODO: test different loadOps
  - TODO?: resolveTarget mip level {0, >0} (TODO?: different mip level from colorAttachment)
  - TODO?: resolveTarget {2d array layer, TODO: 3d slice} {0, >0} with {2d, TODO: 3d} resolveTarget
    (different z from colorAttachment)
`
  )
  .params(u =>
    u
      .combine('colorFormat', kColorTextureFormats)
      .filter(t => isTextureFormatPossiblyResolvable(t.colorFormat))
      .combine('separateResolvePass', [false, true])
      .combine('storeOperation', ['discard', 'store'] as const)
      .beginSubcases()
      .combine('transientColorAttachment', [false, true])
      // Exclude if transient AND (separate pass OR storing)
      .unless(
        t => t.transientColorAttachment && (t.separateResolvePass || t.storeOperation === 'store')
      )
      .combine('numColorAttachments', [2, 4] as const)
      .combine('slotsToResolve', kSlotsToResolve)
      .combine('resolveTargetBaseMipLevel', [0, 1] as const)
      .combine('resolveTargetBaseArrayLayer', [0, 1] as const)
      .combine('transientDepthStencilAttachment', [false, true])
      .combine('depthStencilAttachment', [false, true])
      .unless(t => !t.depthStencilAttachment && t.transientDepthStencilAttachment)
  )
  .fn(t => {
    const { colorFormat } = t.params;
    t.skipIfTextureFormatNotSupported(colorFormat);
    t.skipIfTextureFormatNotResolvable(colorFormat);
    // MAINTENANCE_TODO(#4509): Remove this when TRANSIENT_ATTACHMENT is added to the WebGPU spec.
    if (t.params.transientColorAttachment || t.params.transientDepthStencilAttachment) {
      t.skipIfTransientAttachmentNotSupported();
    }

    const targets: GPUColorTargetState[] = [];
    for (let i = 0; i < t.params.numColorAttachments; i++) {
      targets.push({ format: colorFormat });
    }

    let depthStencil: GPUDepthStencilState | undefined;
    if (t.params.depthStencilAttachment) {
      depthStencil = {
        format: kDepthStencilFormat,
        depthWriteEnabled: false,
      };
    }

    // These shaders will draw a white triangle into a texture. After draw, the top left
    // half of the texture will be white, and the bottom right half will be unchanged. When this
    // texture is resolved, there will be two distinct colors in each portion of the texture, as
    // well as a line between the portions that contain the midpoint color due to the multisample
    // resolve.
    const pipeline = t.device.createRenderPipeline({
      layout: 'auto',
      vertex: {
        module: t.device.createShaderModule({
          code: `
            @vertex fn main(
              @builtin(vertex_index) VertexIndex : u32
              ) -> @builtin(position) vec4<f32> {
              var pos : array<vec2<f32>, 3> = array<vec2<f32>, 3>(
                  vec2<f32>(-1.0, -1.0),
                  vec2<f32>(-1.0,  1.0),
                  vec2<f32>( 1.0,  1.0));
              return vec4<f32>(pos[VertexIndex], 0.0, 1.0);
            }`,
        }),
        entryPoint: 'main',
      },
      fragment: {
        module: t.device.createShaderModule({
          code: `
            struct Output {
              @location(0) fragColor0 : vec4<f32>,
              @location(1) fragColor1 : vec4<f32>,
              @location(2) fragColor2 : vec4<f32>,
              @location(3) fragColor3 : vec4<f32>,
            };

            @fragment fn main() -> Output {
              return Output(
                vec4<f32>(1.0, 1.0, 1.0, 1.0),
                vec4<f32>(1.0, 1.0, 1.0, 1.0),
                vec4<f32>(1.0, 1.0, 1.0, 1.0),
                vec4<f32>(1.0, 1.0, 1.0, 1.0)
              );
            }`,
        }),
        entryPoint: 'main',
        targets,
      },
      depthStencil,
      primitive: { topology: 'triangle-list' },
      multisample: { count: 4 },
    });

    const resolveTargets: GPUTexture[] = [];
    const drawPassAttachments: GPURenderPassColorAttachment[] = [];
    const resolvePassAttachments: GPURenderPassColorAttachment[] = [];

    // The resolve target must be the same size as the color attachment. If we're resolving to mip
    // level 1, the resolve target base mip level should be 2x the color attachment size.
    const kResolveTargetSize = kSize << t.params.resolveTargetBaseMipLevel;

    for (let i = 0; i < t.params.numColorAttachments; i++) {
      const colorAttachment = t
        .createTextureTracked({
          format: colorFormat,
          size: [kSize, kSize, 1],
          sampleCount: 4,
          mipLevelCount: 1,
          usage: t.params.transientColorAttachment
            ? GPUTextureUsage.RENDER_ATTACHMENT | GPUTextureUsage.TRANSIENT_ATTACHMENT
            : GPUTextureUsage.RENDER_ATTACHMENT,
        })
        .createView();

      let resolveTarget: GPUTextureView | undefined;
      if (t.params.slotsToResolve.includes(i)) {
        const resolveTargetTexture = t.createTextureTracked({
          format: colorFormat,
          size: [kResolveTargetSize, kResolveTargetSize, t.params.resolveTargetBaseArrayLayer + 1],
          sampleCount: 1,
          mipLevelCount: t.params.resolveTargetBaseMipLevel + 1,
          usage: GPUTextureUsage.COPY_SRC | GPUTextureUsage.RENDER_ATTACHMENT,
        });
        resolveTargets.push(resolveTargetTexture);

        resolveTarget = resolveTargetTexture.createView({
          baseMipLevel: t.params.resolveTargetBaseMipLevel,
          baseArrayLayer: t.params.resolveTargetBaseArrayLayer,
        });
      }

      // Clear to black for the load operation. After the draw, the top left half of the attachment
      // will be white and the bottom right half will be black.
      if (t.params.separateResolvePass) {
        drawPassAttachments.push({
          view: colorAttachment,
          clearValue: { r: 0.0, g: 0.0, b: 0.0, a: 0.0 },
          loadOp: 'clear',
          storeOp: 'store',
        });
        resolvePassAttachments.push({
          view: colorAttachment,
          resolveTarget,
          loadOp: 'load',
          storeOp: t.params.storeOperation,
        });
      } else {
        drawPassAttachments.push({
          view: colorAttachment,
          resolveTarget,
          clearValue: { r: 0.0, g: 0.0, b: 0.0, a: 0.0 },
          loadOp: 'clear',
          storeOp: t.params.storeOperation,
        });
      }
    }

    let depthStencilAttachment: GPURenderPassDepthStencilAttachment | undefined;
    if (t.params.depthStencilAttachment) {
      const depthStencilTexture = t.createTextureTracked({
        format: kDepthStencilFormat,
        size: [kSize, kSize, 1],
        sampleCount: 4,
        usage: t.params.transientDepthStencilAttachment
          ? GPUTextureUsage.RENDER_ATTACHMENT | GPUTextureUsage.TRANSIENT_ATTACHMENT
          : GPUTextureUsage.RENDER_ATTACHMENT,
      });
      depthStencilAttachment = {
        view: depthStencilTexture.createView(),
        depthClearValue: 1.0,
        depthLoadOp: 'clear',
        depthStoreOp: 'discard',
        stencilLoadOp: 'clear',
        stencilStoreOp: 'discard',
      };
    }

    const encoder = t.device.createCommandEncoder();
    const pass = encoder.beginRenderPass({
      colorAttachments: drawPassAttachments,
      depthStencilAttachment,
    });
    pass.setPipeline(pipeline);
    pass.draw(3);
    pass.end();
    if (t.params.separateResolvePass) {
      const pass = encoder.beginRenderPass({
        colorAttachments: resolvePassAttachments,
        depthStencilAttachment,
      });
      pass.end();
    }
    t.device.queue.submit([encoder.finish()]);

    // Verify the resolve targets contain the correct values. Note that we use z to specify the
    // array layer from which to pull the pixels for testing.
    const z = t.params.resolveTargetBaseArrayLayer;
    for (const resolveTarget of resolveTargets) {
      ttu.expectSinglePixelComparisonsAreOkInTexture(
        t,
        { texture: resolveTarget, mipLevel: t.params.resolveTargetBaseMipLevel },
        // Note: Channels that do not exist in the actual texture are not compared.
        [
          // Top left pixel should be {1.0, 1.0, 1.0, 1.0}.
          { coord: { x: 0, y: 0, z }, exp: { R: 1.0, G: 1.0, B: 1.0, A: 1.0 } },
          // Bottom right pixel should be {0, 0, 0, 0}.
          { coord: { x: kSize - 1, y: kSize - 1, z }, exp: { R: 0, G: 0, B: 0, A: 0 } },
          // Top right pixel should be {0.5, 0.5, 0.5, 0.5} due to the multisampled resolve.
          { coord: { x: kSize - 1, y: 0, z }, exp: { R: 0.5, G: 0.5, B: 0.5, A: 0.5 } },
        ]
      );
    }
  });