I create a 128 x 128 grass texture, I then tile sub images over it using glTexSubImage2d, these sub images are loaded using the glpng library and have valid alpha value! but when I run my app the transparent areas are black! instead of showing the grass in the main texture! here is some of my code can you help. oid COpenGLView::InitGL() { glClearColor(0.0f, 0.0f, 0.0f, 1.0f) ; glShadeModel(GL_FLAT); //glEnable(GL_DEPTH_TEST); int x,y; for(x =0; x < 128; x++) { for(y = 0; y < 128; y++) { Tile[x][y][0] = 255; Tile[x][y][1] = 0; Tile[x][y][2] = 0; Tile[x][y][3] = 255; } } //SubTile[0] = auxDIBImageLoad("E:\\Grass.bmp"); //SubTile[1] = auxDIBImageLoad("E:\\Wheat.bmp"); pngLoadRaw("E:\\Grass.png",&info[0]); pngLoadRaw("E:\\Marsh.png",&info[1]); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE) ; glEnable(GL_TEXTURE_2D); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 128, 128, 0, GL_RGBA, GL_UNSIGNED_BYTE,Tile) ; glTexSubImage2D(GL_TEXTURE_2D,0,0,0,64,64,GL_RGB,GL_UNSIGNED_BYTE,info[0].Data); glTexSubImage2D(GL_TEXTURE_2D,0,0,64,64,64,GL_RGB,GL_UNSIGNED_BYTE,info[0].Data); glTexSubImage2D(GL_TEXTURE_2D,0,64,0,64,64,GL_RGB,GL_UNSIGNED_BYTE,info[0].Data); glTexSubImage2D(GL_TEXTURE_2D,0,64,64,64,64,GL_RGB,GL_UNSIGNED_BYTE,info[0].Data); } void COpenGLView::DrawGL() { glClear(GL_COLOR_BUFFER_BIT / GL_DEPTH_BUFFER_BIT); //glColor3f(1.0,0.0,0.0); //glPixelStorei(GL_UNPACK_ALIGNMENT, 1) ; glEnable(GL_TEXTURE_2D); //glBindTexture(GL_TEXTURE_2D,texture[0]); glEnable(GL_ALPHA_TEST); glAlphaFunc(GL_GREATER, 0.5); //glEnable(GL_BLEND); //glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glTexSubImage2D(GL_TEXTURE_2D,0,0,0,64,64,GL_RGBA,GL_UNSIGNED_BYTE,info[1].Data); glBegin(GL_QUADS); glTexCoord2f(0,0); glVertex2i(10,138); glTexCoord2f(0,1); glVertex2i(10,10); glTexCoord2f(1,1); glVertex2i(138,10); glTexCoord2f(1,0); glVertex2i(138,138); glEnd(); glDisable(GL_BLEND); glDisable(GL_ALPHA_TEST); //glBindTexture(GL_TEXTURE_2D, texture[1]); //glTexSubImage2D(GL_TEXTURE_2D,0,GL_RGBA,info.Width,info.Height,info.Width, info.Height, //GL_UNSIGNED_BYTE,info.Data ); glFlush(); glDisable(GL_TEXTURE_2D); }