diff --git a/shader/hue.frag b/shader/hue.frag
index 405c91b..5486f6f 100644
--- a/shader/hue.frag
+++ b/shader/hue.frag
@@ -1,48 +1,36 @@
-uniform sampler2D inputTexture;
-uniform float hueAdjust;
+uniform sampler2D texture;
+uniform mediump float hueAdjust;
varying vec2 v_texCoord;
+/* Source: gamedev.stackexchange.com/a/59808/24839 */
+vec3 rgb2hsv(vec3 c)
+{
+ const vec4 K = vec4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);
+ vec4 p = mix(vec4(c.bg, K.wz), vec4(c.gb, K.xy), step(c.b, c.g));
+ vec4 q = mix(vec4(p.xyw, c.r), vec4(c.r, p.yzx), step(p.x, c.r));
+
+ float d = q.x - min(q.w, q.y);
+ /* Avoid divide-by-zero situations by adding a very tiny delta */
+ const float eps = 1.0e-10;
+ return vec3(abs(q.z + (q.w - q.y) / (6.0 * d + eps)), d / (q.x + eps), q.x);
+}
+
+vec3 hsv2rgb(vec3 c)
+{
+ const vec4 K = vec4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);
+ vec3 p = abs(fract(c.xxx + K.xyz) * 6.0 - K.www);
+ return c.z * mix(K.xxx, clamp(p - K.xxx, 0.0, 1.0), c.y);
+}
+
void main ()
{
- const vec4 kRGBToYPrime = vec4 (0.299, 0.587, 0.114, 0.0);
- const vec4 kRGBToI = vec4 (0.596, -0.275, -0.321, 0.0);
- const vec4 kRGBToQ = vec4 (0.212, -0.523, 0.311, 0.0);
+ vec4 color = texture2D (texture, v_texCoord.xy);
+ vec3 hsv = rgb2hsv(color.rgb);
- const vec4 kYIQToR = vec4 (1.0, 0.956, 0.621, 0.0);
- const vec4 kYIQToG = vec4 (1.0, -0.272, -0.647, 0.0);
- const vec4 kYIQToB = vec4 (1.0, -1.107, 1.704, 0.0);
+ hsv.x += hueAdjust;
+ color.rgb = hsv2rgb(hsv);
- /* Sample the input pixel */
- vec4 color = texture2D (inputTexture, v_texCoord.xy);
-
- /* Convert to YIQ */
- float YPrime = dot (color, kRGBToYPrime);
- float I = dot (color, kRGBToI);
- float Q = dot (color, kRGBToQ);
-
- /* Calculate the hue and chroma */
- float hue = atan (Q, I);
- float chroma = sqrt (I * I + Q * Q);
-
- /* Make the user's adjustments */
- hue += hueAdjust;
-
- /* Remember old I and color */
- float IOriginal = I;
- vec4 coOriginal = color;
-
- /* Convert back to YIQ */
- Q = chroma * sin (hue);
- I = chroma * cos (hue);
-
- /* Convert back to RGB */
- vec4 yIQ = vec4 (YPrime, I, Q, 0.0);
- color.r = dot (yIQ, kYIQToR);
- color.g = dot (yIQ, kYIQToG);
- color.b = dot (yIQ, kYIQToB);
-
- /* Save the result */
- gl_FragColor = (IOriginal == 0.0) ? coOriginal : color;
+ gl_FragColor = color;
}
diff --git a/src/bitmap.cpp b/src/bitmap.cpp
index a677207..96cd968 100644
--- a/src/bitmap.cpp
+++ b/src/bitmap.cpp
@@ -854,13 +854,10 @@ void Bitmap::hueChange(int hue)
quad.setTexPosRect(texRect, texRect);
quad.setColor(Vec4(1, 1, 1, 1));
- /* Calculate hue parameter */
- hue = wrapRange(hue, 0, 359);
- float hueAdj = -((M_PI * 2) / 360) * hue;
-
HueShader &shader = shState->shaders().hue;
shader.bind();
- shader.setHueAdjust(hueAdj);
+ /* Shader expects normalized value */
+ shader.setHueAdjust(wrapRange(hue, 0, 359) / 360.0f);
FBO::bind(newTex.fbo);
p->pushSetViewport(shader);
diff --git a/src/shader.cpp b/src/shader.cpp
index 3b22483..824454d 100644
--- a/src/shader.cpp
+++ b/src/shader.cpp
@@ -551,7 +551,6 @@ HueShader::HueShader()
ShaderBase::init();
GET_U(hueAdjust);
- GET_U(inputTexture);
}
void HueShader::setHueAdjust(float value)
@@ -559,11 +558,6 @@ void HueShader::setHueAdjust(float value)
gl.Uniform1f(u_hueAdjust, value);
}
-void HueShader::setInputTexture(TEX::ID tex)
-{
- setTexUniform(u_inputTexture, 0, tex);
-}
-
SimpleMatrixShader::SimpleMatrixShader()
{
diff --git a/src/shader.h b/src/shader.h
index 323b10a..7b4eb02 100644
--- a/src/shader.h
+++ b/src/shader.h
@@ -241,10 +241,9 @@ public:
HueShader();
void setHueAdjust(float value);
- void setInputTexture(TEX::ID tex);
private:
- GLint u_hueAdjust, u_inputTexture;
+ GLint u_hueAdjust;
};
class SimpleMatrixShader : public ShaderBase