void FillPolygonWithVertexColor(float[] vertices, int numVertices)
{
//x,y,r,g,b,a
u_useSolidColor.SetValue(0);
a_position.LoadV2f(vertices, 6, 0);
a_color.LoadV4f(vertices, 6, 2);
GL.DrawArrays(BeginMode.Triangles, 0, numVertices);
}
void DrawLine(float x1, float y1, float x2, float y2)
{
float dx = x2 - x1;
float dy = y2 - y1;
float rad1 = (float)Math.Atan2(
y2 - y1, //dy
x2 - x1); //dx
float[] vtxs = new float[] {
x1, y1, 0, rad1,
x1, y1, 1, rad1,
x2, y2, 0, rad1,
//-------
x2, y2, 1, rad1
};
u_useSolidColor.SetValue(1);
u_solidColor.SetValue(0f, 0f, 0f, 1f);//use solid color
a_position.LoadV4f(vtxs, 4, 0);
u_linewidth.SetValue(2.0f);
GL.DrawArrays(BeginMode.TriangleStrip, 0, 4);
}