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gsdx-ogl: fix logz management (FFXII) 

The issue is that z+1 overflow if z is UINT max
log2(z) overflow if z is 0

So let's use an or 1 to avoid both overflow
This commit is contained in:
Gregory Hainaut 2015-04-25 20:23:26 +02:00
parent ee244071fa
commit 6a3250cad2
2 changed files with 18 additions and 4 deletions
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11
plugins/GSdx/res/glsl/tfx_vgs.glsl
View File

@ -116,6 +116,13 @@ void vs_main()
else
z = i_z;
if(VS_LOGZ == 1) {
// FIXME some games (FFX12 intro) uses MAX_INT as depth parameter. So I replace the +1 with an OR
// Initially a +1 was done to avoid log2(0) (If I'm correct)
// The or mask won't create any overflow
z |= 1u;
}
// pos -= 0.05 (1/320 pixel) helps avoiding rounding problems (integral part of pos is usually 5 digits, 0.05 is about as low as we can go)
// example: ceil(afterseveralvertextransformations(y = 133)) => 134 => line 133 stays empty
// input granularity is 1/16 pixel, anything smaller than that won't step drawing up/left by one pixel
@ -127,13 +134,13 @@ void vs_main()
p.w = 1.0f;
#ifdef ZERO_TO_ONE_DEPTH
if(VS_LOGZ == 1) {
p.z = log2(float(1u+z)) / 32.0f;
p.z = log2(float(z)) / 32.0f;
} else {
p.z = float(z) * exp_min32;
}
#else
if(VS_LOGZ == 1) {
p.z = log2(float(1u+z)) / 31.0f - 1.0f;
p.z = log2(float(z)) / 31.0f - 1.0f;
} else {
p.z = float(z) * exp_min31 - 1.0f;
}

11
plugins/GSdx/res/glsl_source.h
View File

@ -567,6 +567,13 @@ static const char* tfx_vgs_glsl =
" else\n"
" z = i_z;\n"
"\n"
" if(VS_LOGZ == 1) {\n"
" // FIXME some games (FFX12 intro) uses MAX_INT as depth parameter. So I replace the +1 with an OR\n"
" // Initially a +1 was done to avoid log2(0) (If I'm correct)\n"
" // The or mask won't create any overflow\n"
" z |= 1u;\n"
" }\n"
"\n"
" // pos -= 0.05 (1/320 pixel) helps avoiding rounding problems (integral part of pos is usually 5 digits, 0.05 is about as low as we can go)\n"
" // example: ceil(afterseveralvertextransformations(y = 133)) => 134 => line 133 stays empty\n"
" // input granularity is 1/16 pixel, anything smaller than that won't step drawing up/left by one pixel\n"
@ -578,13 +585,13 @@ static const char* tfx_vgs_glsl =
" p.w = 1.0f;\n"
"#ifdef ZERO_TO_ONE_DEPTH\n"
" if(VS_LOGZ == 1) {\n"
" p.z = log2(float(1u+z)) / 32.0f;\n"
" p.z = log2(float(z)) / 32.0f;\n"
" } else {\n"
" p.z = float(z) * exp_min32;\n"
" }\n"
"#else\n"
" if(VS_LOGZ == 1) {\n"
" p.z = log2(float(1u+z)) / 31.0f - 1.0f;\n"
" p.z = log2(float(z)) / 31.0f - 1.0f;\n"
" } else {\n"
" p.z = float(z) * exp_min31 - 1.0f;\n"
" }\n"