#ifdef GL_ES
precision highp float;
#endif

uniform vec2 resolution;
uniform float time;
uniform sampler2D tex0;

void main(void)
{
    vec2 q = gl_FragCoord.xy / resolution.xy;
    vec2 uv = vec2(q.x, 1.0-q.y);
    vec4 color = texture2D(tex0, uv);
    
    //we could move these to uniforms...
    float brightness = 0.5;
    float contrast = 3.0;    

    //ignore alpha
    color.rgb /= color.a;
 
    //apply contrast
    color.rgb = ((color.rgb - 0.5) * max(contrast, 0.0)) + 0.5;

    //apply brightness
    color.rgb += brightness;

    //return alpha
    color.rgb *= color.a;

    gl_FragColor = vec4(color);
}