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wined3d: Get rid of the conditionals in the glsl lit implementation.

This commit is contained in:
Stefan Dösinger 2007-10-28 21:21:24 +01:00 committed by Alexandre Julliard
parent fb0dde7b27
commit 468309e055
1 changed files with 23 additions and 2 deletions
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25
dlls/wined3d/glsl_shader.c
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@ -1777,8 +1777,29 @@ void shader_glsl_lit(SHADER_OPCODE_ARG* arg) {
shader_glsl_add_src_param(arg, arg->src[0], arg->src_addr[0], WINED3DSP_WRITEMASK_1, &src1_param);
shader_glsl_add_src_param(arg, arg->src[0], arg->src_addr[0], WINED3DSP_WRITEMASK_3, &src3_param);
shader_addline(arg->buffer, "vec4(1.0, (%s > 0.0 ? %s : 0.0), (%s > 0.0 ? ((%s > 0.0) ? pow(%s, clamp(%s, -128.0, 128.0)) : 0.0) : 0.0), 1.0)%s);\n",
src0_param.param_str, src0_param.param_str, src0_param.param_str, src1_param.param_str, src1_param.param_str, src3_param.param_str, dst_mask);
/* The sdk specifies the instruction like this
* dst.x = 1.0;
* if(src.x > 0.0) dst.y = src.x
* else dst.y = 0.0.
* if(src.x > 0.0 && src.y > 0.0) dst.z = pow(src.y, power);
* else dst.z = 0.0;
* dst.w = 1.0;
*
* Obviously that has quite a few conditionals in it which we don't like. So the first step is this:
* dst.x = 1.0 ... No further explanation needed
* dst.y = max(src.y, 0.0); ... If x < 0.0, use 0.0, otherwise x. Same as the conditional
* dst.z = x > 0.0 ? pow(max(y, 0.0), p) : 0; ... 0 ^ power is 0, and otherwise we use y anyway
* dst.w = 1.0. ... Nothing fancy.
*
* So we still have one conditional in there. So do this:
* dst.z = pow(max(0.0, src.y) * step(0.0, src.x), power);
*
* step(0.0, x) will return 1 if src.x > 0.0, and 0 otherwise. So if y is 0 we get pow(0.0 * 1.0, power),
* which sets dst.z to 0. If y > 0, but x = 0.0, we get pow(y * 0.0, power), which results in 0 too.
* if both x and y are > 0, we get pow(y * 1.0, power), as it is supposed to
*/
shader_addline(arg->buffer, "vec4(1.0, max(%s, 0.0), pow(max(0.0, %s) * step(0.0, %s), clamp(%s, -128.0, 128.0)), 1.0)%s);\n",
src0_param.param_str, src1_param.param_str, src0_param.param_str, src3_param.param_str, dst_mask);
}
/** Process the WINED3DSIO_DST instruction in GLSL: