Alright can someone tell me what I am missing here? I have a surface being draw to the application surface. The surface being drawn is cleared black with a .5 alpha. If I draw this surface without blend modes the black region looks as it should. Basically it darkens the screen a little. Now when I use this blend mode (I need the multiply blend for additive lighting): Code: gpu_set_blendmode_ext_sepalpha(bm_dest_color, bm_zero, bm_one, bm_zero ) All the black areas revert to full alpha and hide everything. In my mind the alpha should be: (0.5 * 1) + (1*0) = .5 So it should work correctly. However I even tried this code: Code: gpu_set_blendmode_ext_sepalpha(bm_dest_color, bm_zero, bm_zero, bm_zero ) Where the alpha should equate to: (0.5 * 0) + (1*0) = 0 and yet the black portion is still at full alpha. What am I missing here?