Game of Life fragment shader

#version 330 core

in vec2 pos;

layout (location = 0) out vec3 frag_col;

uniform sampler2D input_texture;
uniform bool generate_random;
uniform int width;
uniform int height;

float random (in vec2 st) {
    return fract(sin(dot(st.xy,
                         vec2(12.9898,78.233)))
                 * 43758.5453123);
}

void main() {
    int pixel_size = 2;
    ivec2 screen_pos = ivec2(pos.x * width, pos.y * height);
    if(generate_random) {
        if (random(vec2(screen_pos.x - (screen_pos.x%pixel_size), screen_pos.y - (screen_pos.y%pixel_size))) < 0.5) {
            frag_col = vec3(0.0);
        } else {
            frag_col = vec3(1.0);
        }
        return;
    }

    int wyn = 0;
    wyn += int(texture(input_texture, vec2(pos.x + (pixel_size/float(width)), pos.y + (pixel_size/float(height)))).r);
    wyn += int(texture(input_texture, vec2(pos.x - (pixel_size/float(width)), pos.y + (pixel_size/float(height)))).r);
    wyn += int(texture(input_texture, vec2(pos.x - (pixel_size/float(width)), pos.y - (pixel_size/float(height)))).r);
    wyn += int(texture(input_texture, vec2(pos.x + (pixel_size/float(width)), pos.y - (pixel_size/float(height)))).r);
    wyn += int(texture(input_texture, vec2(pos.x + (pixel_size/float(width)), pos.y)).r);
    wyn += int(texture(input_texture, vec2(pos.x - (pixel_size/float(width)), pos.y)).r);
    wyn += int(texture(input_texture, vec2(pos.x, pos.y + (pixel_size/float(height)))).r);
    wyn += int(texture(input_texture, vec2(pos.x, pos.y - (pixel_size/float(height)))).r);

    int state = int(texture(input_texture, vec2(pos.x, pos.y)).r);

    if(wyn < 2 && state == 1) frag_col = vec3(0.0);
    else if(wyn < 4 && state == 1) frag_col = vec3(1.0);
    else if(state == 1) frag_col = vec3(0.0);
    else if(wyn == 3 && state == 0) frag_col = vec3(1.0f);
    else frag_col = vec3(0.0);


}