// reset our viewport after a window resize
func resizeWindow(width, height int) {
// protect against a divide by zero
if height == 0 {
height = 1
}
// Setup our viewport
gl.Viewport(0, 0, int(width), int(height))
// change to the projection matrix and set our viewing volume.
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
// aspect ratio
aspect := gl.GLdouble(gl.GLfloat(width) / gl.GLfloat(height))
// Set our perspective.
// This code is equivalent to using gluPerspective as in the original tutorial.
var fov, near, far gl.GLdouble
fov = 45.0
near = 0.1
far = 100.0
top := gl.GLdouble(math.Tan(float64(fov*math.Pi/360.0))) * near
bottom := -top
left := aspect * bottom
right := aspect * top
gl.Frustum(float64(left), float64(right), float64(bottom), float64(top), float64(near), float64(far))
// Make sure we're changing the model view and not the projection
gl.MatrixMode(gl.MODELVIEW)
// Reset the view
gl.LoadIdentity()
}
// Handle the window being resized.
func reshape(width int, height int) {
// Render into the entire window.
gl.Viewport(0, 0, width, height)
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
// Configure the Frustrum so the front face of the rendering
// volume fills the screen.
w := float64(width)
h := float64(height)
depth := (w + h) / 2
near := depth / 2.0
right := w / 4.0
top := h / 4.0
far := 4 * depth
gl.Frustum(-right, right, -top, top, near, far)
gl.MatrixMode(gl.MODELVIEW)
gl.LoadIdentity()
// Center the rendering volume in the viewport. Its origin
// is at the far lower left corner.
gl.Translated(-w/2, -h/2, -2*depth)
}
/* new window size or exposure */
func reshape(width int, height int) {
h := float64(height) / float64(width)
gl.Viewport(0, 0, width, height)
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
gl.Frustum(-1.0, 1.0, -h, h, 5.0, 60.0)
gl.MatrixMode(gl.MODELVIEW)
gl.LoadIdentity()
gl.Translatef(0.0, 0.0, -40.0)
}
func (self *Viewport) Perspective(fovy, aspect, zNear, zFar float64) {
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
var xmin, xmax, ymin, ymax float64
ymax = zNear * math.Tan(fovy*math.Pi/360.0)
ymin = -ymax
xmin = ymin * aspect
xmax = ymax * aspect
gl.Frustum(xmin, xmax, ymin, ymax, zNear, zFar)
gl.MatrixMode(gl.MODELVIEW)
gl.Hint(gl.PERSPECTIVE_CORRECTION_HINT, gl.NICEST)
gl.DepthMask(true)
}
func initGl() {
h := float64(height) / float64(width)
gl.Viewport(0, 0, width, height)
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
gl.Frustum(-1.0, 1.0, -h, h, 5.0, 60.0)
gl.MatrixMode(gl.MODELVIEW)
gl.LoadIdentity()
gl.Translatef(0.0, 0.0, -6.0)
gl.EnableClientState(gl.VERTEX_ARRAY)
gl.EnableClientState(gl.TEXTURE_COORD_ARRAY)
gl.VertexPointer(3, 0, &vertices[0][0])
gl.TexCoordPointer(2, 0, &texCoords[0][0])
}
func setup_opengl(width, height int) {
ratio := float64(width) / float64(height)
gl.ShadeModel(gl.SMOOTH)
gl.CullFace(gl.BACK)
gl.FrontFace(gl.CCW)
gl.Enable(gl.CULL_FACE)
gl.ClearColor(0, 0, 0, 0)
gl.Viewport(0, 0, width, height)
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
gluPerspective := func(fovy, aspect, zNear, zFar float64) {
top := math.Tan(fovy*0.5) * zNear
bottom := -top
left := aspect * bottom
right := -left
gl.Frustum(left, right, bottom, top, zNear, zFar)
}
gluPerspective(60.0, ratio, 1.0, 1024.0)
}
