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replace hsl color handling with hsv (#355)

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Scratch 2 color and brightness effects in HSV color space.
This commit is contained in:
Michael "Z" Goddard
2018-10-23 15:13:54 -04:00
committed by GitHub
parent 5bcbc5414f
commit 14813e590c
1 changed files with 17 additions and 17 deletions
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34
src/shaders/sprite.frag
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@@ -54,9 +54,9 @@ varying vec2 v_texCoord;
// Smaller values can cause problems with "color" and "brightness" effects on some mobile devices
const float epsilon = 1e-3;
// Convert an RGB color to Hue, Saturation, and Lightness.
// Convert an RGB color to Hue, Saturation, and Value.
// All components of input and output are expected to be in the [0,1] range.
vec3 convertRGB2HSL(vec3 rgb)
vec3 convertRGB2HSV(vec3 rgb)
{
// Hue calculation has 3 cases, depending on which RGB component is largest, and one of those cases involves a "mod"
// operation. In order to avoid that "mod" we split the M==R case in two: one for G<B and one for B>G. The B>G case
@@ -80,13 +80,13 @@ vec3 convertRGB2HSL(vec3 rgb)
// Chroma = M - m
float C = temp2.x - m;
// Lightness = 1/2 * (M + m)
float L = 0.5 * (temp2.x + m);
// Value = M
float V = temp2.x;
return vec3(
abs(temp2.z + (temp2.w - temp2.y) / (6.0 * C + epsilon)), // Hue
C / (1.0 - abs(2.0 * L - 1.0) + epsilon), // Saturation
L); // Lightness
C / (temp2.x + epsilon), // Saturation
V); // Value
}
vec3 convertHue2RGB(float hue)
@@ -97,11 +97,11 @@ vec3 convertHue2RGB(float hue)
return clamp(vec3(r, g, b), 0.0, 1.0);
}
vec3 convertHSL2RGB(vec3 hsl)
vec3 convertHSV2RGB(vec3 hsv)
{
vec3 rgb = convertHue2RGB(hsl.x);
float c = (1.0 - abs(2.0 * hsl.z - 1.0)) * hsl.y;
return (rgb - 0.5) * c + hsl.z;
vec3 rgb = convertHue2RGB(hsv.x);
float c = hsv.z * hsv.y;
return rgb * c + hsv.z - c;
}
#endif // !defined(DRAW_MODE_silhouette) && (defined(ENABLE_color) || defined(ENABLE_brightness))
@@ -166,7 +166,7 @@ void main()
#if defined(ENABLE_color) || defined(ENABLE_brightness)
{
vec3 hsl = convertRGB2HSL(gl_FragColor.xyz);
vec3 hsv = convertRGB2HSV(gl_FragColor.xyz);
#ifdef ENABLE_color
{
@@ -174,19 +174,19 @@ void main()
// so that some slight change of hue will be visible
const float minLightness = 0.11 / 2.0;
const float minSaturation = 0.09;
if (hsl.z < minLightness) hsl = vec3(0.0, 1.0, minLightness);
else if (hsl.y < minSaturation) hsl = vec3(0.0, minSaturation, hsl.z);
if (hsv.z < minLightness) hsv = vec3(0.0, 1.0, minLightness);
else if (hsv.y < minSaturation) hsv = vec3(0.0, minSaturation, hsv.z);
hsl.x = mod(hsl.x + u_color, 1.0);
if (hsl.x < 0.0) hsl.x += 1.0;
hsv.x = mod(hsv.x + u_color, 1.0);
if (hsv.x < 0.0) hsv.x += 1.0;
}
#endif // ENABLE_color
#ifdef ENABLE_brightness
hsl.z = clamp(hsl.z + u_brightness, 0.0, 1.0);
hsv.z = clamp(hsv.z + u_brightness, 0.0, 1.0);
#endif // ENABLE_brightness
gl_FragColor.rgb = convertHSL2RGB(hsl);
gl_FragColor.rgb = convertHSV2RGB(hsv);
}
#endif // defined(ENABLE_color) || defined(ENABLE_brightness)