Anyone used PgBlt?
Author
Has anyone ever got PgBlt(..) to work. It is supposed to draw a bitmap inside a polygon, specifically a rhombus. But I have never been able to get it to work. One of the arguments is a mono-bitmap for masking.
Has anyone got an example of this function actually working?
the problem why this (and some other blit functions) dont work most of the time is that they need hardware support. i think with GetDeviceCaps you can check if your hardware supports the blit.
My voodoo3 doesnt support anything other then BitBlt
My Homepage
My voodoo3 doesnt support anything other then BitBlt
My Homepage
Author
My solution is to write my own PgBlt function to draw a DIB in a polygon with A being the top-left point B the top-tight and C the bottom left point of the polygon:
Or something like that. On a 500Mhz computer I think this would be fast enough for simple applications such as displaying a rotating bitmap. I haven't tried it yet. If someone wants to try it, and see if I made any mistakes here. You could try it with GetPixel() and SetPixel() but I have found them to be extremely slow.
[edited by - paulbird on April 28, 2003 1:15:45 PM]
void PgBlt(TDC *source, TDC *dest, TPoint pA,TPoint pB, TPoint pC){//get pointer to data of DIB CreateCompatibleDIB(...,DIB_RGB,....,**data,....);//get pointer to data of output DIB CreateCompatibleDIB(...,DIB_RGB,....,**data2,....);//or something like that similar.int a=pA.x, b=pB.x, c=pC.x;int A=pA.y, B=pB.y, C=pC.y;for(i=MIN(a,b,c);i<MAX(a,b,c);i++) for(j=MIN(A,B,C);j<MAX(A,B,C);j++) if( PixelIsInPolygon(i,j,pA,pB,pC) ){//find the co-ordinates of the soure bitmap to use pixX=((i-A)*(c-a)-(C-A)*(j-a))/((B-A)*(c-a)-(C-A)*(b-a))*dib.Width(); pixY=((B-A)*(j-a)-(i-A)*(b-a))/((B-A)*(c-a)-(C-A)*(b-a))*dib.Height(); int bit =pixX + pixY * dib.Width(); int bit2=i + j * dib2.Width();//set the RGB components of the output data2[bit2*3+0] = data[bit*3+0]; data2[bit2*3+1] = data[bit*3+1]; data2[bit2*3+2] = data[bit*3+2]; }} Or something like that. On a 500Mhz computer I think this would be fast enough for simple applications such as displaying a rotating bitmap. I haven't tried it yet. If someone wants to try it, and see if I made any mistakes here. You could try it with GetPixel() and SetPixel() but I have found them to be extremely slow.
[edited by - paulbird on April 28, 2003 1:15:45 PM]
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