A shader test for vkrunner that draws a voronoi tunnel.

tunnel.shader_test.glsl

[require]
fbsize 800 600

[vertex shader passthrough]

[fragment shader]
#version 450

layout(location = 0) out vec4 out_color;

#define M_PI 3.141592653589793

const vec2 res = vec2(800.0, 600.0);
const float aspect = 1.3333333;
const vec2 center = vec2(0.5 * aspect, 0.5);

vec4 voronoi(in vec2 uv);

vec3 hsv2rgb(in vec3 c)
{
  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);
}

vec3 gcolorhsv(in vec3 c)
{
	return c / vec3(360.0, 100.0, 100.0);
}

vec3 texture(in vec2 uv)
{
	vec4 v = voronoi(uv);
	vec3 chsv = gcolorhsv(vec3(201.0, 66.0, 93.0));
	chsv.x = chsv.x + v.x * 0.3;
	chsv = chsv * smoothstep(-1.0, 1.0, pow(v.w, 3.0) * 0.5 + 0.5);

	return hsv2rgb(chsv);
}

void main()
{
	vec2 uv = gl_FragCoord.xy / res * vec2(aspect, 1.0);
	vec2 v = uv - center;

	float angle = atan(v.y, v.x);
	float polar_x = angle * 0.5 / M_PI + 0.5;
	float polar_y = sqrt(dot(v, v));

	float depth = 2.0 / polar_y;
	vec2 tex_uv;
	tex_uv.x = min(polar_x * 2.0, 2.0 - polar_x * 2.0) * 14.0;
	tex_uv.y = depth * 4.0;

	float fog = clamp(35.0 / pow(depth, 2.5), 0.0, 1.0);
	out_color.rgb = texture(tex_uv) * fog;
	out_color.a = 1.0;
}

// modification of this noise function by Inigo Quilez:
// https://www.shadertoy.com/view/XsXfRH

float hash(in vec2 p)
{
    p  = 50.0 * fract(p * 0.3183099 + vec2(0.71, 0.113));
    return -1.0 + 2.0 * fract(p.x * p.y * (p.x + p.y));
}

float noised(in vec2 x)
{
    vec2 p = floor(x);
    vec2 w = fract(x);
    
#if 0
    // quintic interpolation
    vec2 u = w*w*w*(w*(w*6.0-15.0)+10.0);
    vec2 du = 30.0*w*w*(w*(w-2.0)+1.0);
#else
    // cubic interpolation
    vec2 u = w*w*(3.0-2.0*w);
    vec2 du = 6.0*w*(1.0-w);
#endif    
    
    
    float a = hash(p+vec2(0.0,0.0));
    float b = hash(p+vec2(1.0,0.0));
    float c = hash(p+vec2(0.0,1.0));
    float d = hash(p+vec2(1.0,1.0));
	
    float k0 = a;
    float k1 = b - a;
    float k2 = c - a;
    float k3 = a - b - c + d;

    return k0 + k1 * u.x + k2 * u.y + k3 * u.x * u.y;
}

vec2 v2noise(in vec2 uv)
{
	return vec2(noised(uv + vec2(132.47, 821.12)), noised(uv));
}

vec3 v3noise(in vec2 uv)
{
	return vec3(noised(uv + vec2(828.7, 21.12)),
				noised(uv + vec2(13.258, 12.57)),
				noised(uv + vec2(324.61, 57.8)));
}

// modified version of the following one by Inigo Quilez:
// http://www.iquilezles.org/www/articles/smoothvoronoi/smoothvoronoi.htm

vec4 voronoi(in vec2 uv)
{
	ivec2 p = ivec2(floor(uv));
	vec2 f = fract(uv);

	float res = 8.0;
	ivec2 cell = p;

	for(int j=-1; j<=1; j++) {
		for(int i=-1; i<=1; i++) {
			ivec2 b = ivec2(i, j);
			vec2 r = vec2(b) - f + v2noise(p + b) * 0.5 + 0.5;
			float d = dot(r, r);
			if(d < res) {
				res = d;
				cell = p + b;
			}
		}
	}

	return vec4(v3noise(vec2(cell)) * 0.5 + 0.5, sqrt(res));
}

[test]
draw rect -1 -1 2 2