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Minimap: gamma-correct average texture colour calculation (#9249)
This calculates the average texture colour while heeding the sRGB colourspace.
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@ -2229,6 +2229,48 @@ video::ITexture* TextureSource::getNormalTexture(const std::string &name)
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return NULL;
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}
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namespace {
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// For more colourspace transformations, see for example
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// https://github.com/tobspr/GLSL-Color-Spaces/blob/master/ColorSpaces.inc.glsl
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inline float linear_to_srgb_component(float v)
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{
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if (v > 0.0031308f)
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return 1.055f * powf(v, 1.0f / 2.4f) - 0.055f;
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return 12.92f * v;
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}
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inline float srgb_to_linear_component(float v)
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{
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if (v > 0.04045f)
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return powf((v + 0.055f) / 1.055f, 2.4f);
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return v / 12.92f;
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}
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v3f srgb_to_linear(const video::SColor &col_srgb)
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{
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v3f col(col_srgb.getRed(), col_srgb.getGreen(), col_srgb.getBlue());
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col /= 255.0f;
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col.X = srgb_to_linear_component(col.X);
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col.Y = srgb_to_linear_component(col.Y);
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col.Z = srgb_to_linear_component(col.Z);
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return col;
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}
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video::SColor linear_to_srgb(const v3f &col_linear)
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{
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v3f col;
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col.X = linear_to_srgb_component(col_linear.X);
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col.Y = linear_to_srgb_component(col_linear.Y);
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col.Z = linear_to_srgb_component(col_linear.Z);
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col *= 255.0f;
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col.X = core::clamp<float>(col.X, 0.0f, 255.0f);
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col.Y = core::clamp<float>(col.Y, 0.0f, 255.0f);
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col.Z = core::clamp<float>(col.Z, 0.0f, 255.0f);
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return video::SColor(0xff, myround(col.X), myround(col.Y),
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myround(col.Z));
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}
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}
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video::SColor TextureSource::getTextureAverageColor(const std::string &name)
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{
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video::IVideoDriver *driver = RenderingEngine::get_video_driver();
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@ -2243,9 +2285,7 @@ video::SColor TextureSource::getTextureAverageColor(const std::string &name)
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return c;
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u32 total = 0;
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u32 tR = 0;
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u32 tG = 0;
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u32 tB = 0;
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v3f col_acc(0, 0, 0);
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core::dimension2d<u32> dim = image->getDimension();
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u16 step = 1;
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if (dim.Width > 16)
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@ -2255,17 +2295,14 @@ video::SColor TextureSource::getTextureAverageColor(const std::string &name)
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c = image->getPixel(x,y);
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if (c.getAlpha() > 0) {
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total++;
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tR += c.getRed();
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tG += c.getGreen();
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tB += c.getBlue();
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col_acc += srgb_to_linear(c);
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}
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}
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}
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image->drop();
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if (total > 0) {
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c.setRed(tR / total);
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c.setGreen(tG / total);
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c.setBlue(tB / total);
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col_acc /= total;
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c = linear_to_srgb(col_acc);
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}
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c.setAlpha(255);
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return c;
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