我正在尝试将 DirectX 程序的每一帧都转换为 YUV(用于视频编码)。因此,我首先需要每个帧上每个像素的 RGB(A) 值。我需要从后台缓冲区中获取这些。
因为 DirectX 中没有 glReadPixels,所以我执行以下操作:
ID3D10Texture2D
CopyResource
。 此时我可以使用
D3DX10SaveTextureToFile
并且这个暂存纹理将正确地将后台缓冲区保存为图像。但是,我不想绕道使用磁盘,我想立即获取RGB数据,因此我执行以下操作:
问题:RGB 值是垃圾。这是像素 (1,1) 的示例
这特别奇怪,因为我使用相同的代码来映射另一个暂存纹理(来自另一个屏幕外渲染目标)并且这段代码在那里工作得很好。
这是我的代码:
// Get resource pointer to backbuffer
ID3D10Resource *backbufferRes;
m_D3D->GetRenderTargetView()->GetResource(&backbufferRes);
// Cast backbuffer resource to texture2D
ID3D10Texture2D* tempTexture = 0;
backbufferRes->QueryInterface(__uuidof(ID3D10Texture2D),(LPVOID*) &tempTexture);
backbufferRes->Release();
// Get the descriptor of this texture2D
D3D10_TEXTURE2D_DESC descDefault;
tempTexture->GetDesc(&descDefault);
// Create a staging texture desc based on the texture of the backbuffer
D3D10_TEXTURE2D_DESC descStaging;
descStaging = descDefault;
descStaging.Usage = D3D10_USAGE_STAGING;
descStaging.CPUAccessFlags = D3D10_CPU_ACCESS_READ;
descStaging.BindFlags = 0;
// Create the new empty staging texture
ID3D10Texture2D *texture = 0;
m_D3D->GetDevice()->CreateTexture2D( &descStaging, NULL, &texture);
// Copy the backbuffer texture data (tempTexture) to the staging texture (texture)
m_D3D->GetDevice()->CopyResource(texture, tempTexture);
// This call works perfectly, image is correct!
// D3DX10SaveTextureToFile(texture, D3DX10_IFF_BMP, L"D:\\img.bmp");
// We want to avoid disk access, so instead let's map the texture and read its RGB data
D3D10_MAPPED_TEXTURE2D mappedTexture;
hr = texture->Map(D3D10CalcSubresource(0, 0, 1), D3D10_MAP_READ, 0, &mappedTexture);
FLOAT* m_pBits = (FLOAT*) malloc(4 * descStaging.Width * descStaging.Height * sizeof(FLOAT));
if(!FAILED(hr)) {
memcpy(m_pBits, mappedTexture.pData, 4 * descStaging.Width * descStaging.Height);
texture->Unmap(D3D10CalcSubresource(0, 0, 1));
}
texture->Release();
tempTexture->Release();
fp = fopen("D:\\output.txt", "a");
for( UINT row = 0; row < descStaging.Height; row++ )
{
UINT rowStart = row * mappedTexture.RowPitch / 4;
for( UINT col = 0; col < descStaging.Width; col++ )
{
r = m_pBits[rowStart + col*4 + 0]; // Red (X)
g = m_pBits[rowStart + col*4 + 1]; // Green (Y)
b = m_pBits[rowStart + col*4 + 2]; // Blue (Z)
a = m_pBits[rowStart + col*4 + 3]; // Alpha (W)
// Save pixel values to disk
fprintf(fp, "%d %d - %f %f %f\n", col + 1, row + 1, r, g, b);
}
}
fclose(fp);
有没有人知道问题可能是什么?
非常感谢所有帮助。
最佳答案
老问题,但我认为这可能是问题所在:
使用 texture->Map()
映射纹理后,您尝试一次性将其复制到 m_pBits
中。除非映射纹理的 RowPitch 与其宽度相同(参见 here ),否则这将不起作用。
相反,您必须逐行复制图像:
BYTE* source = static_cast<BYTE*>(mappedTexture.pData);
BYTE& dest = m_pBits;
for (int i = 0; i < IMAGE_HEIGHT; ++i) {
memcpy(dest, source, IMAGE_WIDTH * 4); // for 4 bytes per pixel
source += mappedTexture.RowPitch;
dest += IMAGE_WIDTH * 4;
}
关于DirectX 将后台缓冲区数据写入文件,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/15324627/