Merge pull request #907 from js6i/master
Handle vertex attributes with zero stride
diff --git a/MoltenVK/MoltenVK/GPUObjects/MVKPipeline.mm b/MoltenVK/MoltenVK/GPUObjects/MVKPipeline.mm
index e2d61ec..2afcc78 100644
--- a/MoltenVK/MoltenVK/GPUObjects/MVKPipeline.mm
+++ b/MoltenVK/MoltenVK/GPUObjects/MVKPipeline.mm
@@ -970,9 +970,17 @@
maxBinding = max(pVKVB->binding, maxBinding);
uint32_t vbIdx = getMetalBufferIndexForVertexAttributeBinding(pVKVB->binding);
MTLVertexBufferLayoutDescriptor* vbDesc = plDesc.vertexDescriptor.layouts[vbIdx];
- vbDesc.stride = (pVKVB->stride == 0) ? sizeof(simd::float4) : pVKVB->stride; // Vulkan allows zero stride but Metal doesn't. Default to float4
- vbDesc.stepFunction = mvkMTLVertexStepFunctionFromVkVertexInputRate(pVKVB->inputRate);
- vbDesc.stepRate = 1;
+ if (pVKVB->stride == 0) {
+ // Stride can't be 0, it will be set later to attributes' maximum offset + size
+ // to prevent it from being larger than the underlying buffer permits.
+ vbDesc.stride = 0;
+ vbDesc.stepFunction = MTLVertexStepFunctionConstant;
+ vbDesc.stepRate = 0;
+ } else {
+ vbDesc.stride = pVKVB->stride;
+ vbDesc.stepFunction = mvkMTLVertexStepFunctionFromVkVertexInputRate(pVKVB->inputRate);
+ vbDesc.stepRate = 1;
+ }
}
}
@@ -1004,26 +1012,31 @@
// Vulkan allows offsets to exceed the buffer stride, but Metal doesn't.
// If this is the case, fetch an a translated artificial buffer binding, using the same MTLBuffer,
// but that is translated so that the reduced VA offset fits into the binding stride.
- // Only check non-zero offsets, as it's common for both to be zero when step rate is instance.
- if (vaOffset > 0) {
- const VkVertexInputBindingDescription* pVKVB = pVI->pVertexBindingDescriptions;
- for (uint32_t j = 0; j < vbCnt; j++, pVKVB++) {
- if (pVKVB->binding == pVKVA->binding) {
- if (vaOffset >= pVKVB->stride) {
- // Move vertex attribute offset into the stride. This vertex attribute may be
- // combined with other vertex attributes into the same translated buffer binding.
- // But if the reduced offset combined with the vertex attribute size still won't
- // fit into the buffer binding stride, force the vertex attribute offset to zero,
- // effectively dedicating this vertex attribute to its own buffer binding.
- uint32_t origOffset = vaOffset;
- vaOffset %= pVKVB->stride;
- if (vaOffset + getPixelFormats()->getBytesPerBlock(pVKVA->format) > pVKVB->stride) {
- vaOffset = 0;
- }
- vaBinding = getTranslatedVertexBinding(vaBinding, origOffset - vaOffset, maxBinding);
+ const VkVertexInputBindingDescription* pVKVB = pVI->pVertexBindingDescriptions;
+ for (uint32_t j = 0; j < vbCnt; j++, pVKVB++) {
+ if (pVKVB->binding == pVKVA->binding) {
+ uint32_t attrSize = getPixelFormats()->getBytesPerBlock(pVKVA->format);
+ if (pVKVB->stride == 0) {
+ // The step is set to constant, but we need to change stride to be non-zero for metal.
+ // Look for the maximum offset + size to set as the stride.
+ uint32_t vbIdx = getMetalBufferIndexForVertexAttributeBinding(pVKVB->binding);
+ MTLVertexBufferLayoutDescriptor* vbDesc = plDesc.vertexDescriptor.layouts[vbIdx];
+ uint32_t strideLowBound = vaOffset + attrSize;
+ if (vbDesc.stride < strideLowBound) vbDesc.stride = strideLowBound;
+ } else if (vaOffset >= pVKVB->stride) {
+ // Move vertex attribute offset into the stride. This vertex attribute may be
+ // combined with other vertex attributes into the same translated buffer binding.
+ // But if the reduced offset combined with the vertex attribute size still won't
+ // fit into the buffer binding stride, force the vertex attribute offset to zero,
+ // effectively dedicating this vertex attribute to its own buffer binding.
+ uint32_t origOffset = vaOffset;
+ vaOffset %= pVKVB->stride;
+ if (vaOffset + attrSize > pVKVB->stride) {
+ vaOffset = 0;
}
- break;
+ vaBinding = getTranslatedVertexBinding(vaBinding, origOffset - vaOffset, maxBinding);
}
+ break;
}
}
