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wined3d: Make sure that lit doesn't return NaN.

This commit is contained in:
Stefan Dösinger 2011-08-28 19:50:30 +02:00 committed by Alexandre Julliard
parent d7fa599974
commit ec0ac720bf
1 changed files with 10 additions and 3 deletions
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13
dlls/wined3d/glsl_shader.c
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@ -2713,6 +2713,7 @@ static void shader_glsl_lit(const struct wined3d_shader_instruction *ins)
* if(src.x > 0.0 && src.y > 0.0) dst.z = pow(src.y, power);
* else dst.z = 0.0;
* dst.w = 1.0;
* (where power = src.w clamped between -128 and 128)
*
* 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
@ -2725,11 +2726,17 @@ static void shader_glsl_lit(const struct wined3d_shader_instruction *ins)
*
* 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
* if both x and y are > 0, we get pow(y * 1.0, power), as it is supposed to.
*
* Unfortunately pow(0.0 ^ 0.0) returns NaN on most GPUs, but lit with src.y = 0 and src.w = 0 returns
* a non-NaN value in dst.z. What we return doesn't matter, as long as it is not NaN. Return 0, which is
* what all Windows HW drivers and GL_ARB_vertex_program's LIT do.
*/
shader_addline(ins->ctx->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);
"vec4(1.0, max(%s, 0.0), %s == 0.0 ? 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, src3_param.param_str, src1_param.param_str,
src0_param.param_str, src3_param.param_str, dst_mask);
}
/** Process the WINED3DSIO_DST instruction in GLSL: