CGI/exercise1/glsl/shader.frag

// This source code is property of the Computer Graphics and Visualization 
// chair of the TU Dresden. Do not distribute! 
// Copyright (C) CGV TU Dresden - All Rights Reserved
#version 130

in vec4 fragment_color;
in vec2 vertex_pos;

out vec4 color;

const int i_max = 200;

void main()
{
	float m = 0.3;
	vec2 c = vec2(0.5, 1.5);

	vec2 z = vertex_pos * m;

	int i = 0;

	for(; i < i_max; i++) {
		float x = (z.x * z.x - z.y * z.y) + c.x;
		float y = (z.y * z.x - z.x * z.y) + c.y;

		if (x*x + y*y > 4.0) {
			break;
		}

		z.x = x;
		z.y = y;
	}

	float alpha = 0.0;

	if (i < i_max) {
		alpha = float(i) / float(i_max);
	}

	color = vec4(alpha, alpha, alpha, alpha) * 10.0 * fragment_color;

	 /**** Begin of tasks ***
	 - 1.2.5
	 Implement the pseudo-code for calculating the julia fractal at a point.
	 To get the point you can declare a new "in" variable which contains the
	 position and just use the X- and Y- value. 

	 *** End of tasks ***/
	
}