Accessing Texture Memory directly!!!
Author
I created a texture with the function:
if(FAILED(m_pd3dDevice->CreateTexture(256, 256, 0, 0, D3DFMT_A8R8G8B8, D3DPOOL_MANAGED , &m_pFiremap)))
{
return E_FAIL;
}
Notice that the format of this texture I used is D3DFMT_A8R8G8B8 which reserves 32-bit of memory for it. 8 bits of it serve as blue, 8 as red, green, alpha, respectively.
And here is the code used to color the texture;
D3DLOCKED_RECT surfaceBit;
D3DSURFACE_DESC descBit;
if(FAILED(m_pFiremap->LockRect(0, &surfaceBit, NULL, 0)))
return E_FAIL;
char* surface = (char*)surfaceBit.pBits;
m_pFiremap->GetLevelDesc(0, &descBit);
UINT wtex = descBit.Width;
UINT htex = descBit.Height;
for(UINT y = 0; y < htex; y++)
{
for(UINT x = 0; x < wtex; x = x + 4)
{
surface[y * surfaceBit.Pitch + x] = (char)255;
surface[y * surfaceBit.Pitch + x + 1] = (char)0;
surface[y * surfaceBit.Pitch + x + 2] = (char)0;
surface[y * surfaceBit.Pitch + x + 3] = (char)0;
}
}
m_pFiremap->UnlockRect(0);
I found out that in the 32-bit memory of one pixel on my texture, first 8 is for blue, second 8 is for green, third 8 is for red. It makes sense that the forth 8-bit is for alpha. However, no matter what value I set to the forth 8-bit(I have tried to assign it 0, 1, 255), there is no effect on my texture at all. Can anyone tell me why?
you need to turn on blending, check the docs for the renderstate you need to change.
EDIT: btw you should read/write an entire pixel using a unsigned long. then break/assemble the colors using the shift operator. its MUCH faster then the way you are doing it.
they should work, if not they i either made a type or you are using them wrong.
[edited by - a person on April 20, 2002 2:57:34 AM]
EDIT: btw you should read/write an entire pixel using a unsigned long. then break/assemble the colors using the shift operator. its MUCH faster then the way you are doing it.
// simple macros#define ARGB(a, r, g, b) (((a)<<24)|((r)<<16)|((g)<<8)|(b))#define G_ALPHA(color) (((color)>>24)&0xFF)#define G_RED(color) (((color)>>16)&0xFF)#define G_GRN(color) (((color)>>8)&0xFF)#define G_BLU(color) ((color)&0xFF) they should work, if not they i either made a type or you are using them wrong.
[edited by - a person on April 20, 2002 2:57:34 AM]
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