precision highp float; varying vec2 tc; attribute vec4 p; void main(){ gl_Position=p; tc=vec2(0.5,0.5/8.0)*p.xy+vec2(0.5,6.5/8.0); } precision highp float; varying vec2 tc; uniform sampler2D tex; uniform float b; void main() { vec4 s = texture2D(tex,tc); gl_FragColor.xyz = s.xyz*(b*s.w); }