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rhi: metal: Add support for multiview rendering 

Some shortcomings and unexpected problems are not unlikely.
The basic feature, with 2 views going to a texture array's
0 and 1 elements, seems to be working with macOS, also with
MSAA. Instanced drawing has not been verified. (relevant
because layered rendering works via instancing in Metal
and the QRhi backend has to adjust the instance count
in every draw call)

Fixes: QTBUG-114774
Change-Id: I3655e0d2c658b88c4cd6b52a32f94134324e4ac9
Reviewed-by: Andy Nichols <andy.nichols@qt.io>
bb10
Laszlo Agocs 2023-06-26 12:51:05 +02:00
parent 2a65849e10
commit 74bd7a7019
8 changed files with 114 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/gui/rhi/qrhi.cpp
View File

@ -986,7 +986,9 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general")
the left and right eyes). Rather, the target of a multiview render pass is
always a texture array, automatically rendering to the layer (array element)
corresponding to each view. Therefore this feature implies \l TextureArrays
as well. This enum value has been introduced in Qt 6.7.
as well. Multiview rendering is not supported in combination with
tessellation or geometry shaders. See QRhiColorAttachment::setMultiViewCount()
for further details on multiview rendering. This enum value has been introduced in Qt 6.7.
*/
/*!
@ -2390,17 +2392,18 @@ QRhiColorAttachment::QRhiColorAttachment(QRhiRenderBuffer *renderBuffer)
\l{QRhi::isFeatureSupported()}{isFeatureSupported()}.
\note For portability, be aware of limitations that exist for multiview
rendering with some of the graphics APIs. For example, OpenGL disallows
tessellation or geometry shaders with multiview. With other APIs, e.g.
Vulkan, some of these are optional features, the actual support depending
on the implementation. It is therefore recommended that multiview render
passes do not rely on any of the features that
rendering with some of the graphics APIs. It is recommended that multiview
render passes do not rely on any of the features that
\l{https://registry.khronos.org/OpenGL/extensions/OVR/OVR_multiview.txt}{GL_OVR_multiview}
declares as unsupported. The one exception is shader stage outputs other
than \c{gl_Position} depending on \c{gl_ViewIndex}: that can be relied on
(even with OpenGL) because QRhi never reports multiview as supported without
\c{GL_OVR_multiview2} also being present.
\note Multiview rendering is not supported in combination with tessellation
or geometry shaders, even though some implementations of some graphics APIs
may allow this.
\since 6.7
*/
@ -6816,6 +6819,9 @@ QRhiResource::Type QRhiGraphicsPipeline::resourceType() const
is reported as supported. The render target must be a 2D texture array, and
the color attachment for the render target must have the same \a count set.
See QRhiColorAttachment::setMultiViewCount() for further details on
multiview rendering.
\since 6.7
\sa QRhi::MultiView, QRhiColorAttachment::setMultiViewCount()
*/

119
src/gui/rhi/qrhimetal.mm
View File

@ -377,6 +377,15 @@ struct QMetalGraphicsPipelineData
float slopeScaledDepthBias;
QMetalShader vs;
QMetalShader fs;
struct ExtraBufferManager {
enum class WorkBufType {
DeviceLocal,
HostVisible
};
QMetalBuffer *acquireWorkBuffer(QRhiMetal *rhiD, quint32 size, WorkBufType type = WorkBufType::DeviceLocal);
QVector<QMetalBuffer *> deviceLocalWorkBuffers;
QVector<QMetalBuffer *> hostVisibleWorkBuffers;
} extraBufMgr;
struct Tessellation {
QMetalGraphicsPipelineData *q = nullptr;
bool enabled = false;
@ -410,13 +419,6 @@ struct QMetalGraphicsPipelineData
id<MTLComputePipelineState> vsCompPipeline(QRhiMetal *rhiD, QShader::Variant vertexCompVariant);
id<MTLComputePipelineState> tescCompPipeline(QRhiMetal *rhiD);
id<MTLRenderPipelineState> teseFragRenderPipeline(QRhiMetal *rhiD, QMetalGraphicsPipeline *pipeline);
enum class WorkBufType {
DeviceLocal,
HostVisible
};
QMetalBuffer *acquireWorkBuffer(QRhiMetal *rhiD, quint32 size, WorkBufType type = WorkBufType::DeviceLocal);
QVector<QMetalBuffer *> deviceLocalWorkBuffers;
QVector<QMetalBuffer *> hostVisibleWorkBuffers;
} tess;
void setupVertexInputDescriptor(MTLVertexDescriptor *desc);
void setupStageInputDescriptor(MTLStageInputOutputDescriptor *desc);
@ -580,6 +582,7 @@ bool QRhiMetal::create(QRhi::Flags flags)
if (@available(macOS 10.15, *))
caps.isAppleGPU = [d->dev supportsFamily:MTLGPUFamilyApple7];
caps.maxThreadGroupSize = 1024;
caps.multiView = true;
#elif defined(Q_OS_TVOS)
if ([d->dev supportsFeatureSet: MTLFeatureSet(30003)]) // MTLFeatureSet_tvOS_GPUFamily2_v1
caps.maxTextureSize = 16384;
@ -606,8 +609,10 @@ bool QRhiMetal::create(QRhi::Flags flags)
}
caps.isAppleGPU = true;
if (@available(iOS 13, *)) {
if ([d->dev supportsFamily:MTLGPUFamilyApple4])
if ([d->dev supportsFamily: MTLGPUFamilyApple4])
caps.maxThreadGroupSize = 1024;
if ([d->dev supportsFamily: MTLGPUFamilyApple5])
caps.multiView = true;
}
#endif
@ -834,7 +839,7 @@ bool QRhiMetal::isFeatureSupported(QRhi::Feature feature) const
case QRhi::ThreeDimensionalTextureMipmaps:
return true;
case QRhi::MultiView:
return false;
return caps.multiView;
default:
Q_UNREACHABLE();
return false;
@ -1471,11 +1476,11 @@ void QRhiMetal::setGraphicsPipeline(QRhiCommandBuffer *cb, QRhiGraphicsPipeline
psD->makeActiveForCurrentRenderPassEncoder(cbD);
} else {
// mark work buffers that can now be safely reused as reusable
for (QMetalBuffer *workBuf : psD->d->tess.deviceLocalWorkBuffers) {
for (QMetalBuffer *workBuf : psD->d->extraBufMgr.deviceLocalWorkBuffers) {
if (workBuf && workBuf->lastActiveFrameSlot == currentFrameSlot)
workBuf->lastActiveFrameSlot = -1;
}
for (QMetalBuffer *workBuf : psD->d->tess.hostVisibleWorkBuffers) {
for (QMetalBuffer *workBuf : psD->d->extraBufMgr.hostVisibleWorkBuffers) {
if (workBuf && workBuf->lastActiveFrameSlot == currentFrameSlot)
workBuf->lastActiveFrameSlot = -1;
}
@ -1967,6 +1972,7 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
const quint32 vertexOrIndexCount = indexed ? args.drawIndexed.indexCount : args.draw.vertexCount;
QMetalGraphicsPipelineData::Tessellation &tess(graphicsPipeline->d->tess);
QMetalGraphicsPipelineData::ExtraBufferManager &extraBufMgr(graphicsPipeline->d->extraBufMgr);
const quint32 patchCount = tess.patchCountForDrawCall(vertexOrIndexCount, instanceCount);
QMetalBuffer *vertOutBuf = nullptr;
QMetalBuffer *tescOutBuf = nullptr;
@ -2000,7 +2006,7 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
if (outputBufferBinding >= 0) {
const quint32 workBufSize = tess.vsCompOutputBufferSize(vertexOrIndexCount, instanceCount);
vertOutBuf = tess.acquireWorkBuffer(this, workBufSize);
vertOutBuf = extraBufMgr.acquireWorkBuffer(this, workBufSize);
if (!vertOutBuf)
return;
[computeEncoder setBuffer: vertOutBuf->d->buf[0] offset: 0 atIndex: outputBufferBinding];
@ -2048,7 +2054,7 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
if (outputBufferBinding >= 0) {
const quint32 workBufSize = tess.tescCompOutputBufferSize(patchCount);
tescOutBuf = tess.acquireWorkBuffer(this, workBufSize);
tescOutBuf = extraBufMgr.acquireWorkBuffer(this, workBufSize);
if (!tescOutBuf)
return;
[computeEncoder setBuffer: tescOutBuf->d->buf[0] offset: 0 atIndex: outputBufferBinding];
@ -2056,14 +2062,14 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
if (patchOutputBufferBinding >= 0) {
const quint32 workBufSize = tess.tescCompPatchOutputBufferSize(patchCount);
tescPatchOutBuf = tess.acquireWorkBuffer(this, workBufSize);
tescPatchOutBuf = extraBufMgr.acquireWorkBuffer(this, workBufSize);
if (!tescPatchOutBuf)
return;
[computeEncoder setBuffer: tescPatchOutBuf->d->buf[0] offset: 0 atIndex: patchOutputBufferBinding];
}
if (tessFactorBufferBinding >= 0) {
tescFactorBuf = tess.acquireWorkBuffer(this, patchCount * sizeof(MTLQuadTessellationFactorsHalf));
tescFactorBuf = extraBufMgr.acquireWorkBuffer(this, patchCount * sizeof(MTLQuadTessellationFactorsHalf));
[computeEncoder setBuffer: tescFactorBuf->d->buf[0] offset: 0 atIndex: tessFactorBufferBinding];
}
@ -2072,7 +2078,7 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
quint32 inControlPointCount;
quint32 patchCount;
} params;
tescParamsBuf = tess.acquireWorkBuffer(this, sizeof(params), QMetalGraphicsPipelineData::Tessellation::WorkBufType::HostVisible);
tescParamsBuf = extraBufMgr.acquireWorkBuffer(this, sizeof(params), QMetalGraphicsPipelineData::ExtraBufferManager::WorkBufType::HostVisible);
if (!tescParamsBuf)
return;
params.inControlPointCount = tess.inControlPointCount;
@ -2141,6 +2147,39 @@ void QRhiMetal::tessellatedDraw(const TessDrawArgs &args)
}
}
void QRhiMetal::adjustForMultiViewDraw(quint32 *instanceCount, QRhiCommandBuffer *cb)
{
QMetalCommandBuffer *cbD = QRHI_RES(QMetalCommandBuffer, cb);
const int multiViewCount = cbD->currentGraphicsPipeline->m_multiViewCount;
if (multiViewCount <= 1)
return;
const QMap<int, int> &ebb(cbD->currentGraphicsPipeline->d->vs.nativeShaderInfo.extraBufferBindings);
const int viewMaskBufBinding = ebb.value(QShaderPrivate::MslMultiViewMaskBufferBinding, -1);
if (viewMaskBufBinding == -1) {
qWarning("No extra buffer for multiview in the vertex shader; was it built with --view-count specified?");
return;
}
struct {
quint32 viewOffset;
quint32 viewCount;
} multiViewInfo;
multiViewInfo.viewOffset = 0;
multiViewInfo.viewCount = quint32(multiViewCount);
QMetalBuffer *buf = cbD->currentGraphicsPipeline->d->extraBufMgr.acquireWorkBuffer(this, sizeof(multiViewInfo),
QMetalGraphicsPipelineData::ExtraBufferManager::WorkBufType::HostVisible);
if (buf) {
id<MTLBuffer> mtlbuf = buf->d->buf[0];
char *p = reinterpret_cast<char *>([mtlbuf contents]);
memcpy(p, &multiViewInfo, sizeof(multiViewInfo));
[cbD->d->currentRenderPassEncoder setVertexBuffer: mtlbuf offset: 0 atIndex: viewMaskBufBinding];
// The instance count is adjusted for layered rendering. The vertex shader is expected to contain something like:
// uint gl_ViewIndex = spvViewMask[0] + (gl_InstanceIndex - gl_BaseInstance) % spvViewMask[1];
// where spvViewMask is the buffer with multiViewInfo passed in above.
*instanceCount *= multiViewCount;
}
}
void QRhiMetal::draw(QRhiCommandBuffer *cb, quint32 vertexCount,
quint32 instanceCount, quint32 firstVertex, quint32 firstInstance)
{
@ -2159,6 +2198,8 @@ void QRhiMetal::draw(QRhiCommandBuffer *cb, quint32 vertexCount,
return;
}
adjustForMultiViewDraw(&instanceCount, cb);
if (caps.baseVertexAndInstance) {
[cbD->d->currentRenderPassEncoder drawPrimitives: cbD->currentGraphicsPipeline->d->primitiveType
vertexStart: firstVertex vertexCount: vertexCount instanceCount: instanceCount baseInstance: firstInstance];
@ -2197,6 +2238,8 @@ void QRhiMetal::drawIndexed(QRhiCommandBuffer *cb, quint32 indexCount,
return;
}
adjustForMultiViewDraw(&instanceCount, cb);
if (caps.baseVertexAndInstance) {
[cbD->d->currentRenderPassEncoder drawIndexedPrimitives: cbD->currentGraphicsPipeline->d->primitiveType
indexCount: indexCount
@ -2904,10 +2947,13 @@ void QRhiMetal::beginPass(QRhiCommandBuffer *cb,
for (auto it = rtTex->m_desc.cbeginColorAttachments(), itEnd = rtTex->m_desc.cendColorAttachments();
it != itEnd; ++it)
{
if (it->texture())
if (it->texture()) {
QRHI_RES(QMetalTexture, it->texture())->lastActiveFrameSlot = currentFrameSlot;
else if (it->renderBuffer())
if (it->multiViewCount() >= 2)
cbD->d->currentPassRpDesc.renderTargetArrayLength = NSUInteger(it->multiViewCount());
} else if (it->renderBuffer()) {
QRHI_RES(QMetalRenderBuffer, it->renderBuffer())->lastActiveFrameSlot = currentFrameSlot;
}
if (it->resolveTexture())
QRHI_RES(QMetalTexture, it->resolveTexture())->lastActiveFrameSlot = currentFrameSlot;
}
@ -4295,10 +4341,10 @@ void QMetalGraphicsPipeline::destroy()
d->tess.compTesc.destroy();
d->tess.vertTese.destroy();
qDeleteAll(d->tess.deviceLocalWorkBuffers);
d->tess.deviceLocalWorkBuffers.clear();
qDeleteAll(d->tess.hostVisibleWorkBuffers);
d->tess.hostVisibleWorkBuffers.clear();
qDeleteAll(d->extraBufMgr.deviceLocalWorkBuffers);
d->extraBufMgr.deviceLocalWorkBuffers.clear();
qDeleteAll(d->extraBufMgr.hostVisibleWorkBuffers);
d->extraBufMgr.hostVisibleWorkBuffers.clear();
delete d->bufferSizeBuffer;
d->bufferSizeBuffer = nullptr;
@ -4525,6 +4571,24 @@ static inline MTLPrimitiveType toMetalPrimitiveType(QRhiGraphicsPipeline::Topolo
}
}
static inline MTLPrimitiveTopologyClass toMetalPrimitiveTopologyClass(QRhiGraphicsPipeline::Topology t)
{
switch (t) {
case QRhiGraphicsPipeline::Triangles:
case QRhiGraphicsPipeline::TriangleStrip:
case QRhiGraphicsPipeline::TriangleFan:
return MTLPrimitiveTopologyClassTriangle;
case QRhiGraphicsPipeline::Lines:
case QRhiGraphicsPipeline::LineStrip:
return MTLPrimitiveTopologyClassLine;
case QRhiGraphicsPipeline::Points:
return MTLPrimitiveTopologyClassPoint;
default:
Q_UNREACHABLE();
return MTLPrimitiveTopologyClassTriangle;
}
}
static inline MTLCullMode toMetalCullMode(QRhiGraphicsPipeline::CullMode c)
{
switch (c) {
@ -4765,6 +4829,7 @@ void QMetalGraphicsPipelineData::setupVertexInputDescriptor(MTLVertexDescriptor
desc.attributes[loc].bufferIndex = NSUInteger(firstVertexBinding + it->binding());
}
int bindingIndex = 0;
const NSUInteger viewCount = qMax<NSUInteger>(1, q->multiViewCount());
for (auto it = vertexInputLayout.cbeginBindings(), itEnd = vertexInputLayout.cendBindings();
it != itEnd; ++it, ++bindingIndex)
{
@ -4773,6 +4838,8 @@ void QMetalGraphicsPipelineData::setupVertexInputDescriptor(MTLVertexDescriptor
it->classification() == QRhiVertexInputBinding::PerInstance
? MTLVertexStepFunctionPerInstance : MTLVertexStepFunctionPerVertex;
desc.layouts[layoutIdx].stepRate = NSUInteger(it->instanceStepRate());
if (desc.layouts[layoutIdx].stepFunction == MTLVertexStepFunctionPerInstance)
desc.layouts[layoutIdx].stepRate *= viewCount;
desc.layouts[layoutIdx].stride = it->stride();
}
}
@ -4949,6 +5016,9 @@ bool QMetalGraphicsPipeline::createVertexFragmentPipeline()
QMetalRenderPassDescriptor *rpD = QRHI_RES(QMetalRenderPassDescriptor, m_renderPassDesc);
setupAttachmentsInMetalRenderPassDescriptor(rpDesc, rpD);
if (m_multiViewCount >= 2)
rpDesc.inputPrimitiveTopology = toMetalPrimitiveTopologyClass(m_topology);
rhiD->d->trySeedingRenderPipelineFromBinaryArchive(rpDesc);
if (rhiD->rhiFlags.testFlag(QRhi::EnablePipelineCacheDataSave))
@ -5471,7 +5541,7 @@ id<MTLRenderPipelineState> QMetalGraphicsPipelineData::Tessellation::teseFragRen
return ps;
}
QMetalBuffer *QMetalGraphicsPipelineData::Tessellation::acquireWorkBuffer(QRhiMetal *rhiD, quint32 size, WorkBufType type)
QMetalBuffer *QMetalGraphicsPipelineData::ExtraBufferManager::acquireWorkBuffer(QRhiMetal *rhiD, quint32 size, WorkBufType type)
{
QVector<QMetalBuffer *> *workBuffers = type == WorkBufType::DeviceLocal ? &deviceLocalWorkBuffers : &hostVisibleWorkBuffers;
@ -5537,6 +5607,9 @@ bool QMetalGraphicsPipeline::createTessellationPipelines(const QShader &tessVert
return false;
}
if (m_multiViewCount >= 2)
qWarning("Multiview is not supported with tessellation");
// Now the vertex shader is a compute shader.
// It should have three dedicated *VertexAsComputeShader variants.
// What the requested variant was (Standard or Batchable) plays no role here.

2
src/gui/rhi/qrhimetal_p.h
View File

@ -482,6 +482,7 @@ public:
};
};
void tessellatedDraw(const TessDrawArgs &args);
void adjustForMultiViewDraw(quint32 *instanceCount, QRhiCommandBuffer *cb);
QRhi::Flags rhiFlags;
bool importedDevice = false;
@ -499,6 +500,7 @@ public:
QVector<int> supportedSampleCounts;
bool isAppleGPU = false;
int maxThreadGroupSize = 512;
bool multiView = false;
} caps;
QRhiMetalData *d = nullptr;

8
tests/manual/rhi/multiview/buildshaders.bat
View File

@ -1,4 +1,4 @@
qsb --view-count 2 --glsl "300 es,330" --hlsl 61 -c multiview.vert -o multiview.vert.qsb
qsb --glsl "300 es,330" --hlsl 61 -c multiview.frag -o multiview.frag.qsb
qsb --glsl "300 es,330" --hlsl 61 -c texture.vert -o texture.vert.qsb
qsb --glsl "300 es,330" --hlsl 61 -c texture.frag -o texture.frag.qsb
qsb --view-count 2 --glsl "300 es,330" --hlsl 61 -c --msl 12 multiview.vert -o multiview.vert.qsb
qsb --glsl "300 es,330" --hlsl 61 -c --msl 12 multiview.frag -o multiview.frag.qsb
qsb --glsl "300 es,330" --hlsl 61 -c --msl 12 texture.vert -o texture.vert.qsb
qsb --glsl "300 es,330" --hlsl 61 -c --msl 12 texture.frag -o texture.frag.qsb

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tests/manual/rhi/multiview/multiview.frag.qsb
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tests/manual/rhi/multiview/multiview.vert.qsb
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tests/manual/rhi/multiview/texture.frag.qsb
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tests/manual/rhi/multiview/texture.vert.qsb
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