void main() {
/* get vertex info */
vec4 info = texture2D(texture, coord);
/* add the drop to the height */
float drop = max(0.0, 1.0 – length(center * 0.5 + 0.5 – coord) / radius);
drop = 0.5 – cos(drop * PI) * 0.5;
info.r += drop * strength;
gl_FragColor = info;
}
‘);
this.updateShader = new GL.Shader(vertexShader, ‘
uniform sampler2D texture;
uniform vec2 delta;
varying vec2 coord;
void main() {
/* get vertex info */
vec4 info = texture2D(texture, coord);
/* calculate average neighbor height */
vec2 dx = vec2(delta.x, 0.0);
vec2 dy = vec2(0.0, delta.y);
float average = (
texture2D(texture, coord – dx).r +
texture2D(texture, coord – dy).r +
texture2D(texture, coord + dx).r +
texture2D(texture, coord + dy).r
) * 0.25;
/* change the velocity to move toward the average */
info.g += (average – info.r) * 2.0;
/* attenuate the velocity a little so waves do not last forever */
