graph.frag

/*
           co3moz
     github.com/co3moz

     draw => for y-finite solutions
     drawYInfinite => for y-infinite solutions

     press left button of mouse and move for move.
     press right button of mouse and move for scale.
     press shift and left button of mouse, move a little bit will reset to default position.
*/

precision highp float;
uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;
varying vec2 surfacePosition;

#define draw(function, r, g, b) if(distance(function(p.x - c.x), p.y - c.y) < 0.01) color = vec3(r, g, b)
#define drawYInfinite(function, r, g, b) if(distance(function(p.x - c.x), p.y - c.y) < abs(function(p.x - c.x) - function(p.x - c.x - 0.01))) color = vec3(r, g, b)
#define mouseTrack(function) if(distance(mouse.x * aspect.x, p.x) < 0.003 && function(p.x - c.x) - p.y + c.y > 0.0 && sin((c.y - p.y) * 200.0) < 0.1) color = vec3(0.5, 0.5, 0.5)

float y1(float x) {
	return x;
}

float y2(float x) {
	return sin(x);
}

float y3(float x) {
	return sin(x + time);
}

void main(void) {
	vec2 aspect = resolution.xy / min(resolution.x, resolution.y);
	vec2 c = vec2(0.5) * aspect - surfacePosition * 1.5;
	vec2 p = gl_FragCoord.xy / min(resolution.x, resolution.y);
	vec3 color = vec3(0.0);
	
	draw(y1, 1.0, 1.0, 1.0); // y1
	draw(y2, 0.0, 0.0, 1.0); // y2
	draw(y3, 0.0, 1.0, 1.0); // y3
	mouseTrack(y3); // mouse tracking
	
	if(distance(p.y, c.y) < 0.005 && sin((c.x - p.x) * 200.0) < 0.1) color = vec3(0.0, 1.0, 0.0); // horizontal
	if(distance(p.x, c.x) < 0.005 && sin((c.y - p.y) * 200.0) < 0.1) color = vec3(1.0, 0.0, 1.0); // vertical
	gl_FragColor = vec4(color, 1.0);
}

float fn(float x) {
    return length(vec3(x) * mat3(x, cos(time * 10.0), tan(time), 1.0, 0.0, -1.0, -0.0, -1.0, 0.0));
}