#define PI 3.1415926535897932384626433832795 uniform float deformation; varying vec4 vertColor; void main() { vertColor = gl_Color; vec4 pos_vertex = gl_Vertex; float sign = sign(pos_vertex.y); float add_y = cos(pos_vertex.x * PI * 0.5) * deformation; pos_vertex.y += add_y * sign; gl_Position = gl_ModelViewProjectionMatrix * pos_vertex; }