puzzle.frag

#ifdef GL_ES
#define LOWP lowp
precision mediump float;
#else
#define LOWP 
#endif

varying vec2 vTexCoord0;
varying vec2 vTexCoord1;
varying LOWP vec4 vColor;

uniform sampler2D u_texture0;
uniform sampler2D u_texture1;

void main(void) {
  vec4 texColor0 = texture2D(u_texture0, vTexCoord0);
  vec4 texColor1 = texture2D(u_texture1, vTexCoord1);
  gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}

puzzle.vert

attribute vec4 a_position;
attribute vec4 a_color;
attribute vec2 a_texCoord0;
attribute vec2 a_texCoord1;

uniform mat4 u_projTrans;

varying vec2 vTexCoord0;
varying vec2 vTexCoord1;
varying vec4 vColor;

void main() {
  vColor = a_color;
  vTexCoord0 = a_texCoord0;
  vTexCoord1 = a_texCoord1;
  gl_Position = u_projTrans * a_position;
}