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GPU: Truncate fragment values to 15-bit RGB

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This commit is contained in:
Connor McLaughlin 2019-11-02 00:01:03 +10:00
parent bbd7798ca4
commit fc09b722ea
1 changed files with 52 additions and 44 deletions
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70
src/core/gpu_hw.cpp
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@ -281,20 +281,17 @@ uniform vec2 u_transparent_alpha;
out vec4 o_col0;
vec4 ApplyDithering(vec4 col)
ivec3 ApplyDithering(ivec3 icol)
{
ivec3 icol = ivec3(col.rgb * vec3(255.0, 255.0, 255.0));
// apply dither
ivec2 fc = (ivec2(gl_FragCoord.xy) / ivec2(RESOLUTION_SCALE, RESOLUTION_SCALE)) & ivec2(3, 3);
int offset = s_dither_values[fc.y * 4 + fc.x];
icol += ivec3(offset, offset, offset);
return icol + ivec3(offset, offset, offset);
}
// saturate
ivec3 TruncateTo15Bit(ivec3 icol)
{
icol = clamp(icol, ivec3(0, 0, 0), ivec3(255, 255, 255));
// clip to 5-bit range
return vec4((icol.rgb >> 3) / vec3(31.0, 31.0, 31.0), col.a);
return (icol & ivec3(~7, ~7, ~7)) | ((icol >> 3) & ivec3(7, 7, 7));
}
#if TEXTURED
@ -315,7 +312,7 @@ ivec2 ApplyTextureWindow(ivec2 coords)
return (ApplyNativeTextureWindow(downscaled_coords) * ivec2(RESOLUTION_SCALE)) + coords_offset;
}
vec4 SampleFromVRAM(vec2 coord)
ivec4 SampleFromVRAM(vec2 coord)
{
// from 0..1 to 0..255
ivec2 icoord = ivec2(coord * vec2(255 * RESOLUTION_SCALE));
@ -350,27 +347,51 @@ vec4 SampleFromVRAM(vec2 coord)
color = texelFetch(samp0, palette_icoord, 0);
#endif
return color;
return ivec4(color * vec4(255.0, 255.0, 255.0, 255.0));
}
#endif
void main()
{
ivec3 vertcol = ivec3(v_col0 * vec3(255.0, 255.0, 255.0));
bool semitransparent;
bool new_mask_bit;
ivec3 icolor;
#if TEXTURED
vec4 texcol = SampleFromVRAM(v_tex0);
if (texcol == vec4(0.0, 0.0, 0.0, 0.0))
ivec4 texcol = SampleFromVRAM(v_tex0);
if (texcol == ivec4(0.0, 0.0, 0.0, 0.0))
discard;
vec3 color;
// Grab semitransparent bit from the texture color.
semitransparent = (texcol.a != 0);
#if RAW_TEXTURE
color = texcol.rgb;
icolor = texcol.rgb;
#else
color = vec3((ivec3(v_col0 * 255.0) * ivec3(texcol.rgb * 255.0)) >> 7) / 255.0;
icolor = (vertcol * texcol.rgb) >> 7;
#endif
#else
// All pixels are semitransparent for untextured polygons.
semitransparent = true;
icolor = vertcol;
#endif
// Apply dithering
#if DITHERING
icolor = ApplyDithering(icolor);
#endif
// Clip to 15-bit range
icolor = TruncateTo15Bit(icolor);
// Normalize
vec3 color = vec3(icolor) / vec3(255.0, 255.0, 255.0);
#if TRANSPARENCY
// Apply semitransparency. If not a semitransparent texel, destination alpha is ignored.
if (texcol.a != 0)
if (semitransparent)
{
#if TRANSPARENCY_ONLY_OPAQUE
discard;
@ -385,20 +406,7 @@ void main()
o_col0 = vec4(color, 0.0);
}
#else
// Mask bit from texture.
o_col0 = vec4(color, texcol.a);
#endif
#else
#if TRANSPARENCY
o_col0 = vec4(v_col0 * u_transparent_alpha.x, u_transparent_alpha.y);
#else
// Mask bit is cleared for untextured polygons.
o_col0 = vec4(v_col0, 0.0);
#endif
#endif
#if DITHERING
o_col0 = ApplyDithering(o_col0);
o_col0 = vec4(color, 0.0);
#endif
}
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