Mouse threashold shader.

mouse_threashold.vert

// http://editor.thebookofshaders.com/

#ifdef GL_ES
precision mediump float;
#endif

uniform vec2 u_resolution;
uniform vec2 u_mouse;
uniform float u_time;

void main() {
    vec2 st = gl_FragCoord.xy/u_resolution.xy;
    st.x *= u_resolution.x/u_resolution.y;
    
    vec3 color = vec3(step(u_mouse.y/u_resolution.y, st.y));

    gl_FragColor = vec4(color,1.0);
}