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Minimap: gamma-correct average texture colour calculation (#9249)

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This calculates the average texture colour while heeding the sRGB colourspace.
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HybridDog 2021-11-26 19:30:49 +01:00 committed by GitHub
parent 206e131854
commit 7a1464d783
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 46 additions and 9 deletions
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55
src/client/tile.cpp
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@ -2229,6 +2229,48 @@ video::ITexture* TextureSource::getNormalTexture(const std::string &name)
return NULL;
}
namespace {
// For more colourspace transformations, see for example
// https://github.com/tobspr/GLSL-Color-Spaces/blob/master/ColorSpaces.inc.glsl
inline float linear_to_srgb_component(float v)
{
if (v > 0.0031308f)
return 1.055f * powf(v, 1.0f / 2.4f) - 0.055f;
return 12.92f * v;
}
inline float srgb_to_linear_component(float v)
{
if (v > 0.04045f)
return powf((v + 0.055f) / 1.055f, 2.4f);
return v / 12.92f;
}
v3f srgb_to_linear(const video::SColor &col_srgb)
{
v3f col(col_srgb.getRed(), col_srgb.getGreen(), col_srgb.getBlue());
col /= 255.0f;
col.X = srgb_to_linear_component(col.X);
col.Y = srgb_to_linear_component(col.Y);
col.Z = srgb_to_linear_component(col.Z);
return col;
}
video::SColor linear_to_srgb(const v3f &col_linear)
{
v3f col;
col.X = linear_to_srgb_component(col_linear.X);
col.Y = linear_to_srgb_component(col_linear.Y);
col.Z = linear_to_srgb_component(col_linear.Z);
col *= 255.0f;
col.X = core::clamp<float>(col.X, 0.0f, 255.0f);
col.Y = core::clamp<float>(col.Y, 0.0f, 255.0f);
col.Z = core::clamp<float>(col.Z, 0.0f, 255.0f);
return video::SColor(0xff, myround(col.X), myround(col.Y),
myround(col.Z));
}
}
video::SColor TextureSource::getTextureAverageColor(const std::string &name)
{
video::IVideoDriver *driver = RenderingEngine::get_video_driver();
@ -2243,9 +2285,7 @@ video::SColor TextureSource::getTextureAverageColor(const std::string &name)
return c;
u32 total = 0;
u32 tR = 0;
u32 tG = 0;
u32 tB = 0;
v3f col_acc(0, 0, 0);
core::dimension2d<u32> dim = image->getDimension();
u16 step = 1;
if (dim.Width > 16)
@ -2255,17 +2295,14 @@ video::SColor TextureSource::getTextureAverageColor(const std::string &name)
c = image->getPixel(x,y);
if (c.getAlpha() > 0) {
total++;
tR += c.getRed();
tG += c.getGreen();
tB += c.getBlue();
col_acc += srgb_to_linear(c);
}
}
}
image->drop();
if (total > 0) {
c.setRed(tR / total);
c.setGreen(tG / total);
c.setBlue(tB / total);
col_acc /= total;
c = linear_to_srgb(col_acc);
}
c.setAlpha(255);
return c;