lmap_wave.vert

attribute vec4 a_position;
attribute vec3 a_normal;
attribute vec2 a_texCoord;
attribute vec2 a_texCoord1;
varying vec2 v_texture_coord;
varying vec2 v_texture_coord1;

// height of the wave in world units.
uniform float u_amplitude;

// lenght between crests of the wave in world units.
uniform float u_wavelenght;

// a value between 0 and 1. Usually just feed in cumulative delta time from your app.
// Scale this value to make the waves go slower or faster.
uniform float u_time;

void main(void)
{
    // find the amplitude (between 0 and 1) of each vertex in the wave based on the wavelength.
    // Adding in time value gives constant motion to the wave.
    float factor = fract((a_position.y + (u_time * u_wavelenght))  / u_wavelenght);
    
    // this offsets the wave to give you a scale between 0 and 1 and falling back to 0 again. Without it you will
    // get a sawtooth wave rather than a nice up and down motion.
    factor = abs((factor * 2.0) - 1.0);
    
    // vertex gets moved along it's normal.
    vec4 newPos = vec4(a_position.x + (a_normal.x * factor * u_amplitude),
                       a_position.y + (a_normal.y * factor * u_amplitude),
                       a_position.z + (a_normal.z * factor * u_amplitude),
                       a_position.a);
    
    gl_Position = CC_MVPMatrix * newPos;
    
    // values to be passed to fragment shader
    v_texture_coord = a_texCoord;
    v_texture_coord.y = (1.0 - v_texture_coord.y);
    v_texture_coord1 = a_texCoord1;
    v_texture_coord1.y = (1.0 - v_texture_coord1.y);
}