better rendering with hsv

Fragment.glsl

@@ -5,26 +5,57 @@ uniform int iterationCount;
 
 in vec2 complexPos;
 
-vec3 getColor(in float value){
+vec3 hsvToRgb(in float h, in float s, in float v){
-    vec3 red = vec3(1, 0, 0);
+    if (h >= 360)
-    vec3 blue = vec3(0, 0, 1);
+        h -= 360;
-    return value * red + (1 - value) * blue;
+    float c = v * s;
+    float x = c * (1 - abs(mod(h / 60, 2) - 1));
+    float m = v - c;
+    vec3 rgbT;
+    if (0 <= h && h < 60)
+        rgbT = vec3(c, x, 0);
+    if (60 <= h && h < 120)
+        rgbT = vec3(x, c, 0);
+    if (120 <= h && h < 180)
+        rgbT = vec3(0, c, x);
+    if (180 <= h && h < 240)
+        rgbT = vec3(0, x, c);
+    if (240 <= h && h < 300)
+        rgbT = vec3(x, 0, c);
+    if (300 <= h && h < 360)
+        rgbT = vec3(c, 0, x);
+    vec3 rgb = rgbT + m;
+    return rgb;
+}
+
+vec3 getColor(in float modifier){
+    float value = 1;
+    if (modifier >= 1)
+        value = 0;
+    float hue = modifier * 360;
+    float sat = 1;
+
+    return hsvToRgb(hue, sat, value);
 }
 
 vec2 square(in vec2 c){
     return vec2(c.x * c.x - c.y * c.y, 2 * c.x * c.y);
 }
 
+vec2 m(in vec2 c){
+    return square(c) + complexPos;
+}
+
 void main(){
 
     vec2 z;
-    float stepsNeeded = 0;
+    int steps = 0;
-    while (stepsNeeded < iterationCount && length(z) < 2){
+    while (steps < iterationCount && length(z) <= 2){
-        z = square(z) + complexPos;
+        z = m(z);
-        ++stepsNeeded;
+        ++steps;
     }
 
-    float value = stepsNeeded / iterationCount;
+    float modifier = sqrt(float(steps) / iterationCount);
-    pixColor = vec4(getColor(value), 1);
+    pixColor = vec4(getColor(modifier), 1);
 }
 

src/Mandelbrot.cpp

@@ -14,7 +14,7 @@ void Mandelbrot::draw(GLuint vao, QOpenGLShaderProgram& shader) {
 }
 
 void Mandelbrot::setShaderValues(QOpenGLShaderProgram &shader) const {
-	shader.setUniformValue("origin", QVector2D(-1, 1));
+	shader.setUniformValue("origin", QVector2D(-2, 1));
 	shader.setUniformValue("size", QVector2D(2, 2));
 	shader.setUniformValue("iterationCount", iterations);
 }