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Fixed downscaler sampling the same pixel over and over...

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(and therefore not averaging anything).
This commit is contained in:
Guillaume Melquiond 2010-12-19 17:55:19 +00:00
parent 36bf147177
commit 596b9585eb
1 changed files with 9 additions and 10 deletions
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19
src/sdl_utils.cpp
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@ -516,22 +516,21 @@ surface scale_surface_blended(const surface &surf, int w, int h, bool optimize)
double xsrc = 0.0;
for(int xdst = 0; xdst != w; ++xdst, xsrc += xratio) {
double red = 0.0, green = 0.0, blue = 0.0, alpha = 0.0;
double summation = 0.0;
// We now have a rectangle, (xsrc,ysrc,xratio,yratio)
// which we want to derive the pixel from
for(double xloc = xsrc; xloc < xsrc+xratio; xloc += 1.0) {
const double xsize = std::min<double>(std::floor(xloc+1.0)-xloc,xsrc+xratio-xloc);
for(double yloc = ysrc; yloc < ysrc+yratio; yloc += 1.0) {
const int xsrcint = std::max<int>(0,std::min<int>(src->w-1,static_cast<int>(xsrc)));
const int ysrcint = std::max<int>(0,std::min<int>(src->h-1,static_cast<int>(ysrc)));
const double ysize = std::min<double>(std::floor(yloc+1.0)-yloc,ysrc+yratio-yloc);
int xloc1 = int(xsrc), xloc2 = std::min<int>(int(xsrc + xratio), src->w - 1);
int yloc1 = int(ysrc), yloc2 = std::min<int>(int(ysrc + yratio), src->h - 1);
for (int xloc = xloc1; xloc <= xloc2; ++xloc)
{
double xsize = std::min<double>(std::min<double>(xloc + 1 - xsrc, xsrc + xratio - xloc), 1.0);
for (int yloc = yloc1; yloc <= yloc2; ++yloc)
{
double ysize = std::min<double>(std::min<double>(yloc + 1 - ysrc, ysrc + yratio - yloc), 1.0);
Uint8 r,g,b,a;
SDL_GetRGBA(src_pixels[ysrcint*src->w + xsrcint],src->format,&r,&g,&b,&a);
SDL_GetRGBA(src_pixels[yloc * src->w + xloc], src->format, &r, &g, &b, &a);
const double value = xsize*ysize*double(a)/255.0;
summation += value;