github/scratch-render
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Use hsl instead of hsv for brightness and color effects

Browse Source
This commit is contained in:
DD Liu 2019-01-09 22:11:49 -05:00
parent e616ab5d35
commit 01f42ddf85
1 changed files with 26 additions and 41 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

67
src/shaders/sprite.frag
View File

@ -54,39 +54,24 @@ 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 Value.
// Convert an RGB color to Hue, Chroma, and Value.
// All components of input and output are expected to be in the [0,1] range.
vec3 convertRGB2HSV(vec3 rgb)
vec3 convertRGB2HCV(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
// will be calculated in the negative and fed through abs() in the hue calculation at the end.
// See also: https://en.wikipedia.org/wiki/HSL_and_HSV#Hue_and_chroma
const vec4 hueOffsets = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
// Based on work by Sam Hocevar and Emil Persson
vec4 P = (rgb.g < rgb.b) ? vec4(rgb.bg, -1.0, 2.0/3.0) : vec4(rgb.gb, 0.0, -1.0/3.0);
vec4 Q = (rgb.r < P.x) ? vec4(P.xyw, rgb.r) : vec4(rgb.r, P.yzx);
float C = Q.x - min(Q.w, Q.y);
float H = abs((Q.w - Q.y) / (6.0 * C + epsilon) + Q.z);
return vec3(H, C, Q.x);
}
// temp1.xy = sort B & G (largest first)
// temp1.z = the hue offset we'll use if it turns out that R is the largest component (M==R)
// temp1.w = the hue offset we'll use if it turns out that R is not the largest component (M==G or M==B)
vec4 temp1 = rgb.b > rgb.g ? vec4(rgb.bg, hueOffsets.wz) : vec4(rgb.gb, hueOffsets.xy);
// temp2.x = the largest component of RGB ("M" / "Max")
// temp2.yw = the smaller components of RGB, ordered for the hue calculation (not necessarily sorted by magnitude!)
// temp2.z = the hue offset we'll use in the hue calculation
vec4 temp2 = rgb.r > temp1.x ? vec4(rgb.r, temp1.yzx) : vec4(temp1.xyw, rgb.r);
// m = the smallest component of RGB ("min")
float m = min(temp2.y, temp2.w);
// Chroma = M - m
float C = temp2.x - m;
// Value = M
float V = temp2.x;
return vec3(
abs(temp2.z + (temp2.w - temp2.y) / (6.0 * C + epsilon)), // Hue
C / (temp2.x + epsilon), // Saturation
V); // Value
vec3 convertRGB2HSL(vec3 rgb)
{
vec3 hcv = convertRGB2HCV(rgb);
float L = hcv.z - hcv.y * 0.5;
float S = hcv.y / (1.0 - abs(L * 2.0 - 1.0) + epsilon);
return vec3(hcv.x, S, L);
}
vec3 convertHue2RGB(float hue)
@ -97,11 +82,11 @@ vec3 convertHue2RGB(float hue)
return clamp(vec3(r, g, b), 0.0, 1.0);
}
vec3 convertHSV2RGB(vec3 hsv)
vec3 convertHSL2RGB(vec3 hsl)
{
vec3 rgb = convertHue2RGB(hsv.x);
float c = hsv.z * hsv.y;
return rgb * c + hsv.z - c;
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;
}
#endif // !defined(DRAW_MODE_silhouette) && (defined(ENABLE_color) || defined(ENABLE_brightness))
@ -166,7 +151,7 @@ void main()
#if defined(ENABLE_color) || defined(ENABLE_brightness)
{
vec3 hsv = convertRGB2HSV(gl_FragColor.xyz);
vec3 hsl = convertRGB2HSL(gl_FragColor.xyz);
#ifdef ENABLE_color
{
@ -174,19 +159,19 @@ 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 (hsv.z < minLightness) hsv = vec3(0.0, 1.0, minLightness);
else if (hsv.y < minSaturation) hsv = vec3(0.0, minSaturation, hsv.z);
if (hsl.z < minLightness) hsl = vec3(0.0, 1.0, minLightness);
else if (hsl.y < minSaturation) hsl = vec3(0.0, minSaturation, hsl.z);
hsv.x = mod(hsv.x + u_color, 1.0);
if (hsv.x < 0.0) hsv.x += 1.0;
hsl.x = mod(hsl.x + u_color, 1.0);
if (hsl.x < 0.0) hsl.x += 1.0;
}
#endif // ENABLE_color
#ifdef ENABLE_brightness
hsv.z = clamp(hsv.z + u_brightness, 0.0, 1.0);
hsl.z = clamp(hsl.z + u_brightness, 0.0, 1.0);
#endif // ENABLE_brightness
gl_FragColor.rgb = convertHSV2RGB(hsv);
gl_FragColor.rgb = convertHSL2RGB(hsl);
}
#endif // defined(ENABLE_color) || defined(ENABLE_brightness)