surfaces question
Author
hi, I'm trying to set a palette on a offscreen surface and then retrieve the actual 32 bit color value from it to copy to a primary surface. The problem is that I have a function which at some point copies a pixel from one surface to another assuming that the data type is the same:
function(UINT * surface1, UINT * surface2);
eg surface1[0] = surface2[0]
Is there any way to get the 32 bit color value from the surface memory of the offscreen surface?
Quote:Original post by staticVoid2Yes, but it involves a large switch() statement, with one case for each D3DFORMAT you want to support.
hi, I'm trying to set a palette on a offscreen surface and then retrieve the actual 32 bit color value from it to copy to a primary surface. The problem is that I have a function which at some point copies a pixel from one surface to another assuming that the data type is the same:
function(UINT * surface1, UINT * surface2);
eg surface1[0] = surface2[0]
Is there any way to get the 32 bit color value from the surface memory of the offscreen surface?
Also, what do you mean a "palette"? Do you mean D3DFORMAT_P8? Because paletteised surfaces aren't supported on any recent card.
Author
I'm using DirectDraw by the way, not Direc3D. I'm trying to create different offscreen surfaces that have different bit-depths and then blt or map them to the 32 bit primary surface.
Ah, that makes it a bit easier then. You can grab the pixel format for each surface and use that. Something like (Off the top of my head, untested):
And ShiftFromMask is:
Actually, if your source format is actually a palettised surface, you can just read the palette with IDirectDrawSurface7::GetPalette
Although, I'd recommend against DirectDraw, you get this sort of thing for free with Direct3D...
// Lock the surfaceDDSURFACEDESC2 desc;memset(&desc, 0, sizeof(desc));desc.dwSize = sizeof(desc);pSurface->Lock(NULL, &desc, 0, NULL);// Get some useful valuesBYTE* pBits = (BYTE*)desc.lpSurface;DWORD nRShift = ShiftFromMask(desc.ddpfPixelFormat.dwRBitMask);DWORD nGShift = ShiftFromMask(desc.ddpfPixelFormat.dwGBitMask);DWORD nBShift = ShiftFromMask(desc.ddpfPixelFormat.dwBBitMask);DWORD dwPixel = 0; // Output pixel in xxrrggbb formatfor(UINT y=0; y<desc.dwHeight; ++y){ BYTE* pRow = pBits + desc.lPitch * y; for(UINT x=0; x<desc.dwWidth; ++x) { DWORD in = 0; // Stride of one pixel depends on bit count if(desc.ddpfPixelFormat.dwRGBBitCount == 32) { // Pixels are 4 bytes in = *(DWORD*)pRow; pRow += 4; dwPixel |= ((in & desc.ddpfPixelFormat.dwRBitMask)>>nRShift)<<24; dwPixel |= ((in & desc.ddpfPixelFormat.dwGBitMask)>>nGShift)<<16; dwPixel |= ((in & desc.ddpfPixelFormat.dwBBitMask)>>nBShift)<<8; } else if(desc.ddpfPixelFormat.dwRGBBitCount == 24) { // Pixels are 3 bytes - Note: Not sure if this reads the bytes in the correct order in |= ((DWORD)pRow[0])<<0; in |= ((DWORD)pRow[1])<<8; in |= ((DWORD)pRow[2])<<16; pRow += 3; dwPixel |= ((in & desc.ddpfPixelFormat.dwRBitMask)>>nRShift)<<24; dwPixel |= ((in & desc.ddpfPixelFormat.dwGBitMask)>>nGShift)<<16; dwPixel |= ((in & desc.ddpfPixelFormat.dwBBitMask)>>nBShift)<<8; } else if(desc.ddpfPixelFormat.dwRGBBitCount == 16) { // Pixels are 2 bytes in = *(WORD*)pRow; pRow += 2; dwPixel |= ((in & desc.ddpfPixelFormat.dwRBitMask)>>nRShift)<<24; dwPixel |= ((in & desc.ddpfPixelFormat.dwGBitMask)>>nGShift)<<16; dwPixel |= ((in & desc.ddpfPixelFormat.dwBBitMask)>>nBShift)<<8; } }}And ShiftFromMask is:
DWORD ShiftFromMask(DWORD dwMask){ for(DWORD i=0; i<32; ++i) { if(dwMask & (1<<i)) return i; } return 32; // Should never happen}Actually, if your source format is actually a palettised surface, you can just read the palette with IDirectDrawSurface7::GetPalette
Although, I'd recommend against DirectDraw, you get this sort of thing for free with Direct3D...
Author
but I take it there's no way to blt a surface to another which has a different bit-depth? and would it be overall more efficient to use palettised surfaces for storing textures because some textures im using only require 16 colors
I'm using directdraw mostly for learning purposes, I know direct3d is faster but I think of It as cheating mostly - when I found out that it done texture mapping, z-buffering, clipping etc. all for you it just put me off, I hate to think what a 3d engine does for you.
#include "3dengine.h"
int main() {
MakeACoolGame();
}
Quote:
Although, I'd recommend against DirectDraw, you get this sort of thing for free with Direct3D...
I'm using directdraw mostly for learning purposes, I know direct3d is faster but I think of It as cheating mostly - when I found out that it done texture mapping, z-buffering, clipping etc. all for you it just put me off, I hate to think what a 3d engine does for you.
#include "3dengine.h"
int main() {
MakeACoolGame();
}
Author
I think I might just add another parameters on the function:
somthing like that, I know ive missed out 16 and 24 bit but you get the idea, although it would probaly slow down my texture mapping function to a crawl to add that extra code in for evey pixel.
[Edited by - staticVoid2 on February 20, 2008 4:27:11 PM]
function(UINT * surface1, void * surface2, int bitsFlag, PALETTEENTRY * palette) {int bitShift = 4;if(palette != NULL) {switch(bitsFlag) { case 1: // similar to 4 break; case 4: { if(bitShift == 4) bitShift = 0; else bitShift = 4; surface1[a] = palette[surface2[a] >> bitShift & 15]; } break; case 8: surface1[a] = palette[surface2[a]]; break;}}} else { if(bitFlag == 32) surface1[a] = surface2[a]}somthing like that, I know ive missed out 16 and 24 bit but you get the idea, although it would probaly slow down my texture mapping function to a crawl to add that extra code in for evey pixel.
[Edited by - staticVoid2 on February 20, 2008 4:27:11 PM]
Quote:Original post by staticVoid2It's been years since I used DirectDraw (I ditched it shortly after DDraw 7 came out), but if the surface Blt() function doesn't handle pixel format conversion (And it wouldn't surprise me if it doesn't), you'll have to do it yourself. DirectDraw is designed to be as low level as possible, so if the Blt() function does do format conversion, every DirectDraw driver would have to support it.
but I take it there's no way to blt a surface to another which has a different bit-depth?
Quote:Original post by staticVoid2I'm not really sure. You won't get any hardware acceleration either way though. It's possibly slower to use palettised surfaces because there's an extra lookup for each pixel, and memory savings aren't really anything to worry about.
and would it be overall more efficient to use palettised surfaces for storing textures because some textures im using only require 16 colors
Quote:Original post by staticVoid2Ha, if only [smile]
I'm using directdraw mostly for learning purposes, I know direct3d is faster but I think of It as cheating mostly - when I found out that it done texture mapping, z-buffering, clipping etc. all for you it just put me off, I hate to think what a 3d engine does for you.
#include "3dengine.h"
int main() {
MakeACoolGame();
}
Using DirectDraw for learning purposes is fine, so long as you realise that DDraw doesn't have any hardware acceleration at all (On all but a few specialised graphics cards) - so your graphics card doesn't matter at all, and that D3D is much easier for most things. If you're using DirectDraw for learning about rasterisation and the like, then sure, go for it - that's how I started with DirectX stuff.
Author
Quote:
and memory savings aren't really anything to worry about.
but say I had a 800x600 texture as a 32-bit surface, would that not require around 1.8MB of video memory? and what if you have a 16MB graphics card? that would mean you could only store around 8 of these textures without using system memory.
Quote:Original post by staticVoid2DirectDraw isn't hardware accelerated, so it wouldn't use any graphics memory, it uses system memory.
but say I had a 800x600 texture as a 32-bit surface, would that not require around 1.8MB of video memory? and what if you have a 16MB graphics card? that would mean you could only store around 8 of these textures without using system memory.
In any case, 1.8MB would be just over 10% of the total vram, and you're not going to have 10 of them around are you?
If you want to support systems with a 16MB graphics card, go ahead - but then you could argue you should support Windows 95 / 98, since that's the sort of era you'd get a 16MB graphics card in.
Author
Quote:
DirectDraw isn't hardware accelerated, so it wouldn't use any graphics memory, it uses system memory.
why does it give the option between video and surface memory when creating surfaces then?
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