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Code Issues Releases Activity

Corrected blit8bppAlphaTo24bpp function. Can anyone give me some hints to further improve this algorithm?

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This commit is contained in:
phoebus118 2008-03-04 13:59:34 +00:00
parent 9b9a9b455f
commit 4f3ca5613e
1 changed files with 38 additions and 18 deletions
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56
SDL_Extensions.cpp
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@ -8,6 +8,7 @@
#include "CMessage.h"
#include <boost/algorithm/string.hpp>
#include "hch\CDefHandler.h"
#include <map>
extern SDL_Color playerColorPalette[256];
@ -488,6 +489,7 @@ SDL_Surface * CSDL_Ext::secondAlphaTransform(SDL_Surface * src, SDL_Surface * al
int CSDL_Ext::blit8bppAlphaTo24bpp(SDL_Surface * src, SDL_Rect * srcRect, SDL_Surface * dst, SDL_Rect * dstRect)
{
static std::map<Uint8, int> st;
if(src && src->format->BytesPerPixel==1 && dst && (dst->format->BytesPerPixel==3 || dst->format->BytesPerPixel==4)) //everything's ok
{
SDL_Rect fulldst;
@ -583,7 +585,25 @@ int CSDL_Ext::blit8bppAlphaTo24bpp(SDL_Surface * src, SDL_Rect * srcRect, SDL_Su
{
SDL_Color tbc = src->format->palette->colors[*((Uint8*)src->pixels + (y+sr.y)*src->pitch + x + sr.x)]; //color to blit
Uint8 * p = (Uint8*)dst->pixels + (y+dstRect->y)*dst->pitch + (x+dstRect->x)*dst->format->BytesPerPixel; //place to blit at
switch ((Uint32)tbc.unused) {
// According analyze, the values of tbc.unused are fixed,
// and the approximate ratios are as following:
//
// tbc.unused numbers
// 192 2679
// 164 326907
// 82 705590
// 214 1292625
// 128 4842923
// 0 72138078
// 255 77547326
//
// By making use of such characteristic, we may implement a
// very fast algorithm for heroes3 without loose much quality.
switch ((Uint32)tbc.unused)
{
case 255:
break;
case 0:
p[0] = (Uint32)tbc.r;
p[1] = (Uint32)tbc.g;
@ -594,15 +614,13 @@ int CSDL_Ext::blit8bppAlphaTo24bpp(SDL_Surface * src, SDL_Rect * srcRect, SDL_Su
p[1] = ((Uint32)tbc.g + (Uint32)p[1]) >> 1;
p[2] = ((Uint32)tbc.b + (Uint32)p[2]) >> 1;
break;
case 255:
break;
default:
//p[0] = ((((Uint32)tbc.r-(Uint32)p[0])*(Uint32)tbc.unused) >> 8 + p[0]) & 0xFF;
//p[1] = ((((Uint32)tbc.g-(Uint32)p[1])*(Uint32)tbc.unused) >> 8 + p[1]) & 0xFF;
//p[2] = ((((Uint32)tbc.b-(Uint32)p[2])*(Uint32)tbc.unused) >> 8 + p[2]) & 0xFF;
p[0] = ((Uint32)tbc.unused*(Uint32)p[0] + (Uint32)tbc.r*(Uint32)(255-tbc.unused))>>8; //red
p[1] = ((Uint32)tbc.unused*(Uint32)p[1] + (Uint32)tbc.g*(Uint32)(255-tbc.unused))>>8; //green
p[2] = ((Uint32)tbc.unused*(Uint32)p[2] + (Uint32)tbc.b*(Uint32)(255-tbc.unused))>>8; //blue
p[0] = ((((Uint32)p[0]-(Uint32)tbc.r)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.r) & 0xFF;
p[1] = ((((Uint32)p[1]-(Uint32)tbc.g)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.g) & 0xFF;
p[2] = ((((Uint32)p[2]-(Uint32)tbc.b)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.b) & 0xFF;
//p[0] = ((Uint32)tbc.unused*(Uint32)p[0] + (Uint32)tbc.r*(Uint32)(255-tbc.unused))>>8; //red
//p[1] = ((Uint32)tbc.unused*(Uint32)p[1] + (Uint32)tbc.g*(Uint32)(255-tbc.unused))>>8; //green
//p[2] = ((Uint32)tbc.unused*(Uint32)p[2] + (Uint32)tbc.b*(Uint32)(255-tbc.unused))>>8; //blue
break;
}
}
@ -616,7 +634,11 @@ int CSDL_Ext::blit8bppAlphaTo24bpp(SDL_Surface * src, SDL_Rect * srcRect, SDL_Su
{
SDL_Color tbc = src->format->palette->colors[*((Uint8*)src->pixels + (y+sr.y)*src->pitch + x + sr.x)]; //color to blit
Uint8 * p = (Uint8*)dst->pixels + (y+dstRect->y)*dst->pitch + (x+dstRect->x)*dst->format->BytesPerPixel; //place to blit at
switch ((Uint32)tbc.unused) {
switch ((Uint32)tbc.unused)
{
case 255:
break;
case 0:
p[2] = (Uint32)tbc.r;
p[1] = (Uint32)tbc.g;
@ -627,15 +649,13 @@ int CSDL_Ext::blit8bppAlphaTo24bpp(SDL_Surface * src, SDL_Rect * srcRect, SDL_Su
p[1] = ((Uint32)tbc.g + (Uint32)p[1]) >> 1;
p[0] = ((Uint32)tbc.b + (Uint32)p[0]) >> 1;
break;
case 255:
break;
default:
p[2] = ((Uint32)tbc.unused*(Uint32)p[2] + (Uint32)tbc.r*(Uint32)(255-tbc.unused))>>8; //red
p[1] = ((Uint32)tbc.unused*(Uint32)p[1] + (Uint32)tbc.g*(Uint32)(255-tbc.unused))>>8; //green
p[0] = ((Uint32)tbc.unused*(Uint32)p[0] + (Uint32)tbc.b*(Uint32)(255-tbc.unused))>>8; //blue
//p[2] = ((((Uint32)tbc.r-(Uint32)p[2])*(Uint32)tbc.unused) >> 8 + p[2]) & 0xFF;
//p[1] = ((((Uint32)tbc.g-(Uint32)p[1])*(Uint32)tbc.unused) >> 8 + p[1]) & 0xFF;
//p[0] = ((((Uint32)tbc.b-(Uint32)p[0])*(Uint32)tbc.unused) >> 8 + p[0]) & 0xFF;
p[2] = ((((Uint32)p[2]-(Uint32)tbc.r)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.r) & 0xFF;
p[1] = ((((Uint32)p[1]-(Uint32)tbc.g)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.g) & 0xFF;
p[0] = ((((Uint32)p[0]-(Uint32)tbc.b)*(Uint32)tbc.unused) >> 8 + (Uint32)tbc.b) & 0xFF;
//p[2] = ((Uint32)tbc.unused*(Uint32)p[2] + (Uint32)tbc.r*(Uint32)(255-tbc.unused))>>8; //red
//p[1] = ((Uint32)tbc.unused*(Uint32)p[1] + (Uint32)tbc.g*(Uint32)(255-tbc.unused))>>8; //green
//p[0] = ((Uint32)tbc.unused*(Uint32)p[0] + (Uint32)tbc.b*(Uint32)(255-tbc.unused))>>8; //blue
break;
}
}