void GfxGlEngine::drawPicture(const Picture &picture, const int dx, const int dy, Rect* clipRect)
{
GLuint aTextureID = picture.getGlTextureID();
float x0 = (float)( dx+picture.getOffset().getX());
float x1 = x0+picture.getWidth();
float y0 = (float)(dy-picture.getOffset().getY());
float y1 = y0+picture.getHeight();
// Bind the texture to which subsequent calls refer to
glBindTexture( GL_TEXTURE_2D, aTextureID);
glBegin( GL_QUADS );
//Bottom-left vertex (corner)
glTexCoord2i( 0, 0 );
glVertex2f( x0, y0 );
//Bottom-right vertex (corner)
glTexCoord2i( 1, 0 );
glVertex2f( x1, y0 );
//Top-right vertex (corner)
glTexCoord2i( 1, 1 );
glVertex2f( x1, y1 );
//Top-left vertex (corner)
glTexCoord2i( 0, 1 );
glVertex2f( x0, y1 );
glEnd();
}
void GfxGlEngine::unloadPicture(Picture &ioPicture)
{
const GLuint& texture = (GLuint)ioPicture.getGlTextureID();
glDeleteTextures(1, &texture );
SDL_FreeSurface(ioPicture.getSurface());
ioPicture = Picture();
}
void GfxGlEngine::loadPicture(Picture& ioPicture)
{
GLuint& texture(ioPicture.getGlTextureID());
SDL_Surface *surface = ioPicture.getSurface();
GLenum texture_format;
GLint nOfColors;
// SDL_Surface *surface2
// get the number of channels in the SDL surface
nOfColors = surface->format->BytesPerPixel;
if (nOfColors == 4) // contains an alpha channel
{
if (surface->format->Rmask == 0x000000ff)
texture_format = GL_RGBA;
else
texture_format = GL_BGRA;
}
else if (nOfColors == 3) // no alpha channel
{
if (surface->format->Rmask == 0x000000ff)
texture_format = GL_RGB;
else
texture_format = GL_BGR;
}
else
{
THROW("Invalid image format");
}
if (texture == 0)
{
// the picture has no texture ID!
// generate a texture ID
glGenTextures( 1, &texture );
}
// Bind the texture object
glBindTexture( GL_TEXTURE_2D, texture );
// Set the texture's stretching properties
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST );
// Edit the texture object's image data using the information SDL_Surface gives us
ioPicture.lock();
glTexImage2D( GL_TEXTURE_2D, 0, nOfColors, surface->w, surface->h, 0,
texture_format, GL_UNSIGNED_BYTE, surface->pixels );
ioPicture.unlock();
}
