diff --git a/shader/hue.frag b/shader/hue.frag index 405c91b..61143ac 100644 --- a/shader/hue.frag +++ b/shader/hue.frag @@ -1,48 +1,40 @@ -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. + * Since we always deal with underlying 8-Bit color values, this + * should never mask a real value */ + 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