<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head> <meta content="text/html; charset=windows-1251" http-equiv="Content-Type"> <title>texture_environment_combiners_NV_ATI_ARB</title></head><body>case GL_SUBTRACT: <------> color_combine = (R200_TXC_ARG_B_ZERO | <------><------><------>  R200_TXC_COMP_ARG_B |. <------><------><------>  R200_TXC_NEG_ARG_C | <------><------><------>  R200_TXC_OP_MADD); <------> R200_COLOR_ARG( 0, A ); <------> R200_COLOR_ARG( 1, C ); <airlied> AndrewR: generally you have a negative bit, so you just feed in arg1 and negative arg2 and arg0 == 1<code> R200_TXC_NEG_ARG_A (1 << 19) <AndrewR> so, for four-component input one can just set arg0 == arg3 == 1, then negate arg 2 and freed arg 1, and execute add (NV version) </code> case GL_ADD: <------> color_combine = (R200_TXC_ARG_B_ZERO | <------><------><------>  R200_TXC_COMP_ARG_B |. <------><------><------>  R200_TXC_OP_MADD); <------> R200_COLOR_ARG( 0, A ); <------> R200_COLOR_ARG( 1, C ); ARB_texture_env_combine operations in terms of NV_texture_env_combine4 NV extension: <pre>REPLACE Arg0 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, 1, 1, 0) MODULATE Arg0 * Arg1 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, arg1, 1, 0) ADD Arg0 + Arg1 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, 1, arg1, 1) ADD_SIGNED_ARB Arg0 + Arg1 - 0.5 = ADD_SIGNED_EXT Arg0 * Arg1 + Arg2 * Arg3 - 0.5 (arg0, 1, 1, arg1) SUBTRACT_ARB Arg0 - Arg1 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, 1, INV(arg1), 1) MODULATE_ADD_ATI Arg0 * Arg2 + Arg1 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, arg1, arg1, 1) MODULATE_SIGNED_ADD_ATI Arg0 * Arg2 + Arg1 - 0.5 = ADD_SIGNED_EXT Arg0 * Arg1 + Arg2 * Arg3 - 0.5 (arg0, arg2, arg1, 1) MODULATE_SUBTRACT_ATI Arg0 * Arg2 - Arg1 = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, arg2, INV(arg1), 1) INTERPOLATE_ARB Arg0 * (Arg2) + Arg1 * (1-Arg2) = ADD Arg0 * Arg1 + Arg2 * Arg3 (arg0, arg2, arg1, INV(arg2)) </pre> </body></html>