Bug 264371 – [WGSL] textureSampleGrad is not implemented

• Component: WebGPU
• Status: RESOLVED FIXED

[Mike Wyrzykowski]

textureSampleGrad should map to sample which takes a gradient (page 202 of the Metal shading language spec)

Open https://webgpu.github.io/webgpu-samples/samples/normalMap.

Note the failure:

MSL compilation error: Error Domain=MTLLibraryErrorDomain Code=3 "program_source:120:26: error: use of undeclared identifier 'textureSampleGrad'
        if ((local7.z >= textureSampleGrad(global11, global8, local7.xy, local2, local3).r)) {
                         ^
" UserInfo={NSLocalizedDescription=program_source:120:26: error: use of undeclared identifier 'textureSampleGrad'
        if ((local7.z >= textureSampleGrad(global11, global8, local7.xy, local2, local3).r)) {


it comes from this WGSL:

 // Walk the depth texture, and stop when the ray intersects the depth map
  var pos = vec3(startUV, 0);
  for (var i = 0; i < 32; i++) {
    if (pos.z >= textureSampleGrad(depthTexture, textureSampler, pos.xy, ddx, ddy).r) {
      break; // Hit the surface
    }
    pos += posDelta;
  }

in https://webgpu.github.io/webgpu-samples/samples/normalMap#./normalMap.wgsl

[Radar WebKit Bug Importer]

<rdar://problem/118084526>

[Tadeu Zagallo]

Pull request: https://github.com/WebKit/WebKit/pull/20162

[EWS]

Committed 270430@main (8af46bcd0f22): <https://commits.webkit.org/270430@main>

Reviewed commits have been landed. Closing PR #20162 and removing active labels.