attribute vec3 aVertexPosition;
attribute vec3 aVertexNormal;
attribute vec2 aTextureCoord;

uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
uniform mat3 uNMatrix;
uniform bool uCistern;
uniform float uWaterHeight;

varying vec2 vTextureCoord;
varying vec3 vTransformedNormal;
varying vec4 vPosition;
varying float colorBlue;

void main(void) {
   if (aVertexPosition.z < uWaterHeight && !uCistern)
      colorBlue = -1.0;
   else
      colorBlue = 1.0;

   vPosition = uMVMatrix * vec4(aVertexPosition, 1.0);
   gl_Position = uPMatrix * vPosition;
   vTextureCoord = aTextureCoord;
   vTransformedNormal = uNMatrix * aVertexNormal;
}