How to read data from UTexture2D in C ++
I am trying to read pixel data from a filled UTexture2D in an Unreal Engine C ++ project. Before asking a question here, I tried to use the method described in this link: https://answers.unrealengine.com/questions/25594/accessing-pixel-values-of-texture2d.html . However, this doesn't work for me. All the pixel values I got from the texture are some garbage data.
I just want to get depth values from SceneCapture2D and post-processing stuff containing SceneTexture: Depth node. I need depth values available in C ++ so that I can continue processing with OpenCV. In Directx11, the placement texture can be used to read the CPU, but in an unreal engine I don't know how to create an "intermediate texture" like Dx11. I cannot get the correct pixel values from the current method, which is why I think I can try to access a texture that is not readable by the processor.
Here is my experimental code for reading RGB data from UTexture2D.
Initialize RGB texture:
VideoTextureColor= UTexture2D::CreateTransient(640, 480, PF_B8G8R8A8);
VideoTextureColor->UpdateResource();
VideoUpdateTextureRegionColor = new FUpdateTextureRegion2D(0, 0, 0, 0, 640, 480);
ColorRegionData = new FUpdateTextureRegionsData;
PixelDepthData.Init(FColor(0, 0, 0, 255), 640 * 480);
// Populate the texture with blue color
for (int i = 0; i < 640; i++) {
for (int j = 0; j < 480; j++) {
int idx = j * 640 + i;
PixelDepthData[idx].B = 255;
PixelDepthData[idx].G = 0;
PixelDepthData[idx].R = 0;
PixelDepthData[idx].A = 255;
}
}
UpdateTextureRegions(
VideoTextureColor,
(int32)0,
(uint32)1,
VideoUpdateTextureRegionColor,
(uint32)(4 * 640),
(uint32)4,
(uint8*)PixelDepthData.GetData(),
false,
ColorRegionData
);
Then update its value back to PixelDepthData (TArray) and update this texture with the values in PixelDepthData, which is its old value.
UpdateTextureRegions(
VideoTextureColor,
(int32)0,
(uint32)1,
VideoUpdateTextureRegionColor,
(uint32)(4 * 640),
(uint32)4,
(uint8*)PixelDepthData.GetData(),
false,
ColorRegionData
);
ENQUEUE_UNIQUE_RENDER_COMMAND_ONEPARAMETER(
FRealSenseDelegator,
ARealSenseDelegator*, RealSenseDelegator, this,
{
FColor* tmpImageDataPtr = static_cast<FColor*>((RealSenseDelegator->VideoTextureColor)->PlatformData->Mips[0].BulkData.Lock(LOCK_READ_ONLY));
for (uint32 j = 0; j < 480; j++) {
for (uint32 i = 0; i < 640; i++) {
uint32 idx = j * 640 + i;
RealSenseDelegator->PixelDepthData[idx] = tmpImageDataPtr[idx];
RealSenseDelegator->PixelDepthData[idx].A = 255;
}
}
(RealSenseDelegator->VideoTextureColor)->PlatformData->Mips[0].BulkData.Unlock();
}
);
All I got was a white texture instead of a blue color texture in the render scene.
Does anyone know how to read the data of a UTexture2D object?
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I understood that. First, you need to get a reference to the RHI UTexture2D texture structure, and then use RHILockTexture2D to read the data, and you have to do this in RenderThread. The following code is just an example:
FTexture2DResource* uTex2DRes = (FTexture2DResource*)(RealSenseDelegator->VideoTexturePixelDepth)->Resource;
float* cpuDataPtr = (float*)RHILockTexture2D(
uTex2DRes->GetTexture2DRHI(),
0,
RLM_ReadOnly,
destStride,
false);
for (uint32 j = 0; j < 480; j++) {
for (uint32 i = 0; i < 640; i++) {
uint32 idx = j * 640 + i;
// TODO Read the pixel data right here
}
}
RHIUnlockTexture2D(uTex2DRes->GetTexture2DRHI(), 0, false);
To do this on the render thread, you must use a macro such as ENQUEUE_UNIQUE_RENDER_COMMAND_ONEPARAMETER // If you only pass one parameter to the render thread, use this one. +
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