/*
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ColorConverter
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you can use it to convert color from RGB space to HSL space and back.
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HSL2RGB copied from GLPaint Apple sample:
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http://developer.apple.com/library/ios/#samplecode/GLPaint/Introduction/Intro.html
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RGB2HSL translated from http://www.geekymonkey.com/Programming/CSharp/RGB2HSL_HSL2RGB.htm
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From: https://github.com/alessani/ColorConverter
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*/
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void HSL2RGB(float h, float s, float l, float *outR, float *outG, float *outB) {
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float temp1, temp2;
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float temp[3];
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int i;
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// Check for saturation. If there isn't any just return the luminance value for each, which results in gray.
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if (s == 0.0) {
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if (outR)
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*outR = l;
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if (outG)
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*outG = l;
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if (outB)
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*outB = l;
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return;
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}
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// Test for luminance and compute temporary values based on luminance and saturation
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if (l < 0.5)
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temp2 = l * (1.0 + s);
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else
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temp2 = l + s - l * s;
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temp1 = 2.0 * l - temp2;
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// Compute intermediate values based on hue
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temp[0] = h + 1.0 / 3.0;
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temp[1] = h;
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temp[2] = h - 1.0 / 3.0;
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for (i = 0; i < 3; ++i) {
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// Adjust the range
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if (temp[i] < 0.0)
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temp[i] += 1.0;
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if (temp[i] > 1.0)
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temp[i] -= 1.0;
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if (6.0 * temp[i] < 1.0)
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temp[i] = temp1 + (temp2 - temp1) * 6.0 * temp[i];
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else {
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if (2.0 * temp[i] < 1.0)
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temp[i] = temp2;
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else {
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if (3.0 * temp[i] < 2.0)
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temp[i] = temp1 + (temp2 - temp1) * ((2.0 / 3.0) - temp[i]) * 6.0;
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else
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temp[i] = temp1;
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}
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}
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}
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// Assign temporary values to R, G, B
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if (outR)
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*outR = temp[0];
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if (outG)
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*outG = temp[1];
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if (outB)
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*outB = temp[2];
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}
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void RGB2HSL(float r, float g, float b, float *outH, float *outS, float *outL) {
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/*r = r/255.0f;
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g = g/255.0f;
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b = b/255.0f;*/
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float h, s, l, v, m, vm, r2, g2, b2;
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h = 0;
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s = 0;
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v = MAX(r, g);
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v = MAX(v, b);
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m = MIN(r, g);
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m = MIN(m, b);
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l = (m + v) / 2.0f;
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if (l <= 0.0) {
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if (outH)
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*outH = h;
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if (outS)
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*outS = s;
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if (outL)
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*outL = l;
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return;
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}
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vm = v - m;
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s = vm;
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if (s > 0.0f) {
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s /= (l <= 0.5f) ? (v + m) : (2.0 - v - m);
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} else {
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if (outH)
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*outH = h;
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if (outS)
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*outS = s;
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if (outL)
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*outL = l;
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return;
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}
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r2 = (v - r) / vm;
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g2 = (v - g) / vm;
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b2 = (v - b) / vm;
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if (r == v) {
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h = (g == m ? 5.0f + b2 : 1.0f - g2);
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} else if (g == v) {
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h = (b == m ? 1.0f + r2 : 3.0 - b2);
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} else {
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h = (r == m ? 3.0f + g2 : 5.0f - r2);
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}
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h /= 6.0f;
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if (outH)
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*outH = h;
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if (outS)
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*outS = s;
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if (outL)
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*outL = l;
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}
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