diff options
| -rw-r--r-- | src/gui/rhi/qrhi.cpp | 59 |
1 files changed, 37 insertions, 22 deletions
diff --git a/src/gui/rhi/qrhi.cpp b/src/gui/rhi/qrhi.cpp index bcc1684f5e..b9cf0a1a36 100644 --- a/src/gui/rhi/qrhi.cpp +++ b/src/gui/rhi/qrhi.cpp @@ -493,10 +493,13 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") Flag values to indicate what features are supported by the backend currently in use. \value MultisampleTexture Indicates that textures with a sample count larger - than 1 are supported. + than 1 are supported. In practice this feature will be unsupported with + OpenGL ES versions older than 3.1, and OpenGL older than 3.0. \value MultisampleRenderBuffer Indicates that renderbuffers with a sample - count larger than 1 are supported. + count larger than 1 are supported. In practice this feature will be + unsupported with OpenGL ES 2.0, and may also be unsupported with OpenGL 2.x + unless the relevant extensions are present. \value DebugMarkers Indicates that debug marker groups (and so QRhiCommandBuffer::debugMarkBegin()) are supported. @@ -504,10 +507,15 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") \value Timestamps Indicates that command buffer timestamps are supported. Relevant for QRhiProfiler::gpuFrameTimes(). - \value Instancing Indicates that instanced drawing is supported. + \value Instancing Indicates that instanced drawing is supported. In + practice this feature will be unsupported with OpenGL ES 2.0 and OpenGL + 3.2 or older. - \value CustomInstanceStepRate Indicates that instance step rates other than - 1 are supported. + \value CustomInstanceStepRate Indicates that instance step rates other + than 1 are supported. In practice this feature will always be unsupported + with OpenGL. In addition, running with Vulkan 1.0 without + VK_EXT_vertex_attribute_divisor will also lead to reporting false for this + feature. \value PrimitiveRestart Indicates that restarting the assembly of primitives when encountering an index value of 0xFFFF @@ -535,7 +543,8 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") index buffer offsets (\c{indexOffset + firstIndex * indexComponentSize}) that are not 4 byte aligned are supported. When not supported, attempting to issue a \l{QRhiCommandBuffer::drawIndexed()}{drawIndexed()} with a - non-aligned effective offset may lead to unspecified behavior. + non-aligned effective offset may lead to unspecified behavior. Relevant in + particular for Metal, where this will be reported as unsupported. \value NPOTTextureRepeat Indicates that the \l{QRhiSampler::Repeat}{Repeat} wrap mode and mipmap filtering modes are @@ -546,8 +555,12 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") \value RedOrAlpha8IsRed Indicates that the \l{QRhiTexture::RED_OR_ALPHA8}{RED_OR_ALPHA8} format maps to a one component 8-bit \c red format. This is the case for all backends except - OpenGL, where \c{GL_ALPHA}, a one component 8-bit \c alpha format, is used - instead. This is relevant for shader code that samples from the texture. + OpenGL when using either OpenGL ES or a non-core profile context. There + \c{GL_ALPHA}, a one component 8-bit \c alpha format, is used + instead. Using the special texture format allows having a single code + path for creating textures, leaving it up to the backend to decide the + actual format, while the feature flag can be used to pick the + appropriate shader variant for sampling the texture. \value ElementIndexUint Indicates that 32-bit unsigned integer elements are supported in the index buffer. In practice this is true everywhere except @@ -556,7 +569,8 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") index buffer. \value Compute Indicates that compute shaders, image load/store, and - storage buffers are supported. + storage buffers are supported. OpenGL older than 4.3 and OpenGL ES older + than 3.1 have no compute support. \value WideLines Indicates that lines with a width other than 1 are supported. When reported as not supported, the line width set on the @@ -588,41 +602,42 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general") including the iOS Simulator. \value TriangleFanTopology Indicates that QRhiGraphicsPipeline::setTopology() - supports QRhiGraphicsPipeline::TriangleFan. + supports QRhiGraphicsPipeline::TriangleFan. In practice this feature will be + unsupported with Metal and Direct 3D 11. \value ReadBackNonUniformBuffer Indicates that \l{QRhiResourceUpdateBatch::readBackBuffer()}{reading buffer contents} is supported for QRhiBuffer instances with a usage different than - UniformBuffer. While this is supported in the majority of cases, it will be - unsupported with OpenGL ES older than 3.0. + UniformBuffer. In practice this feature will be unsupported with OpenGL ES + 2.0. \value ReadBackNonBaseMipLevel Indicates that specifying a mip level other than 0 is supported when reading back texture contents. When not supported, specifying a non-zero level in QRhiReadbackDescription leads to returning an all-zero image. In practice this feature will be unsupported with OpenGL - ES 2.0, while it will likely be supported everywhere else. + ES 2.0. - \value TexelFetch Indicates that texelFetch() is available in shaders. In - practice this will be reported as unsupported with OpenGL ES 2.0 and OpenGL - 2.x contexts, because GLSL 100 es and versions before 130 do not support - this function. + \value TexelFetch Indicates that texelFetch() and textureLod() are available + in shaders. In practice this will be reported as unsupported with OpenGL ES + 2.0 and OpenGL 2.x contexts, because GLSL 100 es and versions before 130 do + not support these functions. \value RenderToNonBaseMipLevel Indicates that specifying a mip level other than 0 is supported when creating a QRhiTextureRenderTarget with a QRhiTexture as its color attachment. When not supported, create() will fail whenever the target mip level is not zero. In practice this feature will be - unsupported with OpenGL ES 2.0, while it will likely be supported everywhere - else. + unsupported with OpenGL ES 2.0. \value IntAttributes Indicates that specifying input attributes with signed and unsigned integer types for a shader pipeline is supported. When not supported, build() will succeed but just show a warning message and the values of the target attributes will be broken. In practice this feature - will be unsupported with OpenGL ES 2.0 and OpenGL 2.x, while it will likely - be supported everywhere else. + will be unsupported with OpenGL ES 2.0 and OpenGL 2.x. \value ScreenSpaceDerivatives Indicates that functions such as dFdx(), - dFdy(), and fwidth() are supported in shaders. + dFdy(), and fwidth() are supported in shaders. In practice this feature will + be unsupported with OpenGL ES 2.0 without the GL_OES_standard_derivatives + extension. \value ReadBackAnyTextureFormat Indicates that reading back texture contents can be expected to work for any QRhiTexture::Format. Backends |