op: Implement 'mipmapFilter' test in filter_mode.spec.ts

This PR adds a new test to test that mipmapFilter affects drawing the
slanted plane with different filter modes.

Issue: #2070

src/webgpu/api/operation/sampling/filter_mode.spec.ts

@@ -9,6 +9,172 @@ TODO:
 `;
 
 import { makeTestGroup } from '../../../../common/framework/test_group.js';
+import { assert } from '../../../../common/util/util.js';
 import { GPUTest } from '../../../gpu_test.js';
 
-export const g = makeTestGroup(GPUTest);
+const kRTSize = 16;
+const xMiddle = kRTSize / 2; // we check the pixel value in the middle of the render target
+const kColorAttachmentFormat = 'rgba8unorm';
+const colors = [
+  new Uint8Array([0xff, 0x00, 0x00, 0xff]), // miplevel = 0
+  new Uint8Array([0x00, 0xff, 0x00, 0xff]), // miplevel = 1
+  new Uint8Array([0x00, 0x00, 0xff, 0xff]), // miplevel = 2
+];
+
+class SamplerFilterModeSlantedPlaneTest extends GPUTest {
+  private pipeline: GPURenderPipeline | undefined;
+  async init(): Promise<void> {
+    await super.init();
+
+    this.pipeline = this.device.createRenderPipeline({
+      layout: 'auto',
+      vertex: {
+        module: this.device.createShaderModule({
+          code: `
+            struct Outputs {
+              @builtin(position) Position : vec4<f32>,
+              @location(0) fragUV : vec2<f32>,
+            };
+
+            @vertex fn main(
+              @builtin(vertex_index) VertexIndex : u32) -> Outputs {
+              var position : array<vec3<f32>, 6> = array<vec3<f32>, 6>(
+                vec3<f32>(-0.5, 0.5, -0.5),
+                vec3<f32>(0.5, 0.5, -0.5),
+                vec3<f32>(-0.5, 0.5, 0.5),
+                vec3<f32>(-0.5, 0.5, 0.5),
+                vec3<f32>(0.5, 0.5, -0.5),
+                vec3<f32>(0.5, 0.5, 0.5));
+              // uv is pre-scaled to mimic repeating tiled texture
+              var uv : array<vec2<f32>, 6> = array<vec2<f32>, 6>(
+                vec2<f32>(0.0, 0.0),
+                vec2<f32>(1.0, 0.0),
+                vec2<f32>(0.0, 50.0),
+                vec2<f32>(0.0, 50.0),
+                vec2<f32>(1.0, 0.0),
+                vec2<f32>(1.0, 50.0));
+              // draw a slanted plane in a specific way
+              let matrix : mat4x4<f32> = mat4x4<f32>(
+                vec4<f32>(-1.7320507764816284, 1.8322050568049563e-16, -6.176817699518044e-17, -6.170640314703498e-17),
+                vec4<f32>(-2.1211504944260596e-16, -1.496108889579773, 0.5043753981590271, 0.5038710236549377),
+                vec4<f32>(0.0, -43.63650894165039, -43.232173919677734, -43.18894577026367),
+                vec4<f32>(0.0, 21.693578720092773, 21.789791107177734, 21.86800193786621));
+
+              var output : Outputs;
+              output.fragUV = uv[VertexIndex];
+              output.Position = matrix * vec4<f32>(position[VertexIndex], 1.0);
+              return output;
+            }
+            `,
+        }),
+        entryPoint: 'main',
+      },
+      fragment: {
+        module: this.device.createShaderModule({
+          code: `
+            @group(0) @binding(0) var sampler0 : sampler;
+            @group(0) @binding(1) var texture0 : texture_2d<f32>;
+
+            @fragment fn main(
+              @builtin(position) FragCoord : vec4<f32>,
+              @location(0) fragUV: vec2<f32>)
+              -> @location(0) vec4<f32> {
+                return textureSample(texture0, sampler0, fragUV);
+            }
+            `,
+        }),
+        entryPoint: 'main',
+        targets: [{ format: 'rgba8unorm' }],
+      },
+      primitive: { topology: 'triangle-list' },
+    });
+  }
+
+  // return the render target texture object
+  drawSlantedPlane(textureView: GPUTextureView, sampler: GPUSampler): GPUTexture {
+    // make sure it's already initialized
+    assert(this.pipeline !== undefined);
+
+    const bindGroup = this.device.createBindGroup({
+      entries: [
+        { binding: 0, resource: sampler },
+        { binding: 1, resource: textureView },
+      ],
+      layout: this.pipeline.getBindGroupLayout(0),
+    });
+
+    const colorAttachment = this.device.createTexture({
+      format: kColorAttachmentFormat,
+      size: { width: kRTSize, height: kRTSize, depthOrArrayLayers: 1 },
+      usage: GPUTextureUsage.COPY_SRC | GPUTextureUsage.RENDER_ATTACHMENT,
+    });
+    const colorAttachmentView = colorAttachment.createView();
+
+    const encoder = this.device.createCommandEncoder();
+    const pass = encoder.beginRenderPass({
+      colorAttachments: [
+        {
+          view: colorAttachmentView,
+          storeOp: 'store',
+          clearValue: { r: 0.0, g: 0.0, b: 0.0, a: 1.0 },
+          loadOp: 'clear',
+        },
+      ],
+    });
+    pass.setPipeline(this.pipeline);
+    pass.setBindGroup(0, bindGroup);
+    pass.draw(6);
+    pass.end();
+    this.device.queue.submit([encoder.finish()]);
+
+    return colorAttachment;
+  }
+}
+
+export const g = makeTestGroup(SamplerFilterModeSlantedPlaneTest);
+
+g.test('mipmapFilter')
+  .desc('Test that mipmapFilter affects drawing the slanted plane with different filter modes.')
+  .params(u =>
+    u //
+      .combine('mipmapFilter', ['linear', 'nearest'] as const)
+      .combineWithParams([
+        {
+          results: [
+            { coord: { x: xMiddle, y: 2 }, expected: colors[2] },
+            { coord: { x: xMiddle, y: 6 }, expected: [colors[0], colors[1]] },
+          ],
+        },
+      ])
+  )
+  .fn(async t => {
+    const { mipmapFilter } = t.params;
+
+    const texture = t.createTexture2DWithMipmaps(colors);
+    const textureView = texture.createView();
+
+    const sampler = t.device.createSampler({
+      mipmapFilter,
+    });
+
+    const colorAttachment = t.drawSlantedPlane(textureView, sampler);
+
+    for (const entry of t.params.results) {
+      if (entry.expected instanceof Uint8Array) {
+        // equal exactly one color
+        t.expectSinglePixelIn2DTexture(colorAttachment, kColorAttachmentFormat, entry.coord, {
+          exp: entry.expected,
+        });
+      } else {
+        // a lerp between two colors
+        t.expectSinglePixelBetweenTwoValuesIn2DTexture(
+          colorAttachment,
+          kColorAttachmentFormat,
+          entry.coord,
+          {
+            exp: entry.expected as [Uint8Array, Uint8Array],
+          }
+        );
+      }
+    }
+  });