attribute vec4 aPosition;
attribute vec4 aTextureCoord;
uniform mat4 texMatrix;
uniform mat4 vertexMatrix;
varying vec2 textureCoordinate;
varying vec2 maskCoordinate;
void main() {
    gl_Position = aPosition;
    maskCoordinate = aTextureCoord.xy;
    textureCoordinate = aPosition.xy * 0.5 + 0.5;
}