func (pen *Pen) lineTo(p Point) {
gl.Enable(gl.BLEND)
gl.Enable(gl.POINT_SMOOTH)
gl.Enable(gl.LINE_SMOOTH)
gl.BlendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
gl.Color4f(0.0, 0.0, 0.0, 0.1)
gl.Begin(gl.LINES)
for _, s := range pen.points {
if s.x == 0 && s.y == 0 {
continue
}
if p.distanceTo(s) < 20.0 {
gl.Vertex2i(int(p.x), int(p.y))
gl.Vertex2i(int(s.x), int(s.y))
}
}
gl.End()
pen.n = (pen.n + 1) % len(pen.points)
pen.points[pen.n] = p
pen.moveTo(p)
}
func drawQuad(x, y, w, h int, u, v, u2, v2 float32) {
gl.Begin(gl.QUADS)
gl.TexCoord2f(float32(u), float32(v))
gl.Vertex2i(int(x), int(y))
gl.TexCoord2f(float32(u2), float32(v))
gl.Vertex2i(int(x+w), int(y))
gl.TexCoord2f(float32(u2), float32(v2))
gl.Vertex2i(int(x+w), int(y+h))
gl.TexCoord2f(float32(u), float32(v2))
gl.Vertex2i(int(x), int(y+h))
gl.End()
}
func drawSelection(p1, p2 Point) {
min, max := minMaxPoints(p1, p2)
gl.Color3ub(255, 0, 0)
gl.Begin(gl.LINES)
gl.Vertex2i(int(min.X), int(min.Y))
gl.Vertex2i(int(max.X), int(min.Y))
gl.Vertex2i(int(min.X), int(min.Y))
gl.Vertex2i(int(min.X), int(max.Y))
gl.Vertex2i(int(max.X), int(max.Y))
gl.Vertex2i(int(max.X), int(min.Y))
gl.Vertex2i(int(max.X), int(max.Y))
gl.Vertex2i(int(min.X), int(max.Y))
gl.End()
gl.Color3ub(255, 255, 255)
}