diff options
Diffstat (limited to 'src/resources/image.cpp')
| -rw-r--r-- | src/resources/image.cpp | 79 |
1 files changed, 77 insertions, 2 deletions
diff --git a/src/resources/image.cpp b/src/resources/image.cpp index 7a7e6ac8..b696389f 100644 --- a/src/resources/image.cpp +++ b/src/resources/image.cpp @@ -25,6 +25,7 @@ #include "image.h" #include "../log.h" +#include "../position.h" #ifdef USE_OPENGL bool Image::mUseOpenGL = false; @@ -46,8 +47,7 @@ Image::Image(SDL_Surface *image): } #ifdef USE_OPENGL -Image::Image(GLuint glimage, int width, int height, - int texWidth, int texHeight): +Image::Image(GLuint glimage, int width, int height, int texWidth, int texHeight): mGLImage(glimage), mTexWidth(texWidth), mTexHeight(texHeight), @@ -315,6 +315,81 @@ void Image::setAlpha(float a) } } +Image* Image::merge(Image* image, const Position& pos) +{ + SDL_Surface* surface = new SDL_Surface(*(image->mImage)); + + Uint32 surface_pix, cur_pix; + Uint8 r, g, b, a, p_r, p_g, p_b, p_a; + double f_a, f_ca, f_pa; + SDL_PixelFormat *current_fmt = mImage->format; + SDL_PixelFormat *surface_fmt = surface->format; + int current_offset, surface_offset; + Position offset(0, 0); + + SDL_LockSurface(surface); + SDL_LockSurface(mImage); + // for each pixel lines of a source image + for (offset.x = (pos.x > 0 ? 0 : -pos.x); offset.x < image->getWidth() && + pos.x + offset.x < getWidth(); offset.x++) + { + for (offset.y = (pos.y > 0 ? 0 : -pos.y); offset.y < image->getHeight() + && pos.y + offset.y < getHeight(); offset.y++) + { + // Computing offset on both images + current_offset = (pos.y + offset.y) * getWidth() + pos.x + offset.x; + surface_offset = offset.y * surface->w + offset.x; + + // Retrieving a pixel to merge + surface_pix = ((Uint32*) surface->pixels)[surface_offset]; + cur_pix = ((Uint32*) mImage->pixels)[current_offset]; + + // Retreiving each channel of the pixel using pixel format + r = (Uint8)(((surface_pix & surface_fmt->Rmask) >> + surface_fmt->Rshift) << surface_fmt->Rloss); + g = (Uint8)(((surface_pix & surface_fmt->Gmask) >> + surface_fmt->Gshift) << surface_fmt->Gloss); + b = (Uint8)(((surface_pix & surface_fmt->Bmask) >> + surface_fmt->Bshift) << surface_fmt->Bloss); + a = (Uint8)(((surface_pix & surface_fmt->Amask) >> + surface_fmt->Ashift) << surface_fmt->Aloss); + + // Retreiving previous alpha value + p_a = (Uint8)(((cur_pix & current_fmt->Amask) >> + current_fmt->Ashift) << current_fmt->Aloss); + + // new pixel with no alpha or nothing on previous pixel + if (a == SDL_ALPHA_OPAQUE || (p_a == 0 && a > 0)) + ((Uint32 *)(surface->pixels))[current_offset] = + SDL_MapRGBA(current_fmt, r, g, b, a); + else if (a > 0) + { // alpha is lower => merge color with previous value + f_a = (double) a / 255.0; + f_ca = 1.0 - f_a; + f_pa = (double) p_a / 255.0; + p_r = (Uint8)(((cur_pix & current_fmt->Rmask) >> + current_fmt->Rshift) << current_fmt->Rloss); + p_g = (Uint8)(((cur_pix & current_fmt->Gmask) >> + current_fmt->Gshift) << current_fmt->Gloss); + p_b = (Uint8)(((cur_pix & current_fmt->Bmask) >> + current_fmt->Bshift) << current_fmt->Bloss); + r = (Uint8)((double) p_r * f_ca * f_pa + (double)r * f_a); + g = (Uint8)((double) p_g * f_ca * f_pa + (double)g * f_a); + b = (Uint8)((double) p_b * f_ca * f_pa + (double)b * f_a); + a = (a > p_a ? a : p_a); + ((Uint32 *)(surface->pixels))[current_offset] = + SDL_MapRGBA(current_fmt, r, g, b, a); + } + } + } + SDL_UnlockSurface(surface); + SDL_UnlockSurface(mImage); + + Image* newImage = new Image(surface); + + return newImage; +} + float Image::getAlpha() { return mAlpha; |