94 lines
2.7 KiB
GLSL
94 lines
2.7 KiB
GLSL
#version 120
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uniform vec2 player_pos;
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uniform vec2 resolution; // 720x480
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uniform vec2 offset; // padding in pixels
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uniform float scale; // scale factor
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uniform vec2 torch_lights[32];
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uniform int num_torches;
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uniform float time_sec;
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// External snippet
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// Simplex 2D noise
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// Source: https://gist.github.com/patriciogonzalezvivo/670c22f3966e662d2f83
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vec3 permute(vec3 x) { return mod(((x*34.0)+1.0)*x, 289.0); }
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float snoise(vec2 v){
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const vec4 C = vec4(0.211324865405187, 0.366025403784439,
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-0.577350269189626, 0.024390243902439);
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vec2 i = floor(v + dot(v, C.yy) );
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vec2 x0 = v - i + dot(i, C.xx);
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vec2 i1;
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i1 = (x0.x > x0.y) ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
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vec4 x12 = x0.xyxy + C.xxzz;
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x12.xy -= i1;
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i = mod(i, 289.0);
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vec3 p = permute( permute( i.y + vec3(0.0, i1.y, 1.0 ))
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+ i.x + vec3(0.0, i1.x, 1.0 ));
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vec3 m = max(0.5 - vec3(dot(x0,x0), dot(x12.xy,x12.xy),
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dot(x12.zw,x12.zw)), 0.0);
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m = m*m ;
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m = m*m ;
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vec3 x = 2.0 * fract(p * C.www) - 1.0;
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vec3 h = abs(x) - 0.5;
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vec3 ox = floor(x + 0.5);
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vec3 a0 = x - ox;
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m *= 1.79284291400159 - 0.85373472095314 * ( a0*a0 + h*h );
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vec3 g;
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g.x = a0.x * x0.x + h.x * x0.y;
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g.yz = a0.yz * x12.xz + h.yz * x12.yw;
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return 130.0 * dot(m, g);
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}
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// End of external snippet.
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void main() {
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vec2 virtual_coord = (gl_FragCoord.xy - offset) / scale;
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if (virtual_coord.x < 0.0 || virtual_coord.x > resolution.x ||
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virtual_coord.y < 0.0 || virtual_coord.y > resolution.y) {
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return;
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}
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float p_i_radius = 100.0;
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float p_o_radius = 340.0;
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float t_i_radius = 10.0;
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float t_o_radius = 160.0;
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// player is always at screen center in virtual coords
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vec2 player_screen = vec2(resolution.x / 2.0, resolution.y / 2.0);
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float light_strength = 0.0;
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// Player light
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float d = distance(virtual_coord, player_screen);
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if (d < p_i_radius) {
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light_strength = 1.0;
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} else if (d < p_o_radius) {
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float t = (d - p_i_radius) / (p_o_radius - p_i_radius);
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light_strength = 1.0 - t;
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}
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// Torch lights
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for (int i = 0; i < num_torches; i++) {
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float td = distance(virtual_coord, torch_lights[i]);
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float strength = 0.0;
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if (td < t_i_radius) {
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strength = 1.0;
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} else if (td < t_o_radius) {
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float t = (td - t_i_radius) / (t_o_radius - t_i_radius);
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strength = 1.0 - t;
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}
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light_strength += strength;
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}
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light_strength = clamp(light_strength, 0.0, 1.0);
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// Noise
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vec2 world_coord = (virtual_coord + player_pos - resolution / 2.0) * 0.005;
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float noise = (snoise(world_coord + vec2(time_sec / 5.0, time_sec / 6.0)) + 1.0) / 2.0;
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float t = 1.0 - light_strength;
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float alpha = clamp(t * (1.0 + noise), 0.0, 1.0);
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gl_FragColor = vec4(0.0, 0.0, 0.0, alpha);
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} |