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eoc4: use Matrix4x4 to perform world to canvas scaling.
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Bill Thiede 2021-07-16 19:59:42 -07:00
parent 5df2917668
commit 12c2382327
1 changed files with 8 additions and 5 deletions
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13
rtchallenge/examples/eoc4.rs
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@ -24,7 +24,7 @@ fn main() -> Result<()> {
let w = 200;
let h = w;
let mut c = Canvas::new(w, h);
let t = Matrix4x4::translate(0., 0.75, 0.);
let t = Matrix4x4::translate(0., 0.4, 0.);
let p = Tuple::point(0., 0., 0.);
let rot_hour = Matrix4x4::rotation_z(-PI / 6.);
@ -33,11 +33,14 @@ fn main() -> Result<()> {
let h = h as f32;
let h_w = w / 2.0;
let h_h = h / 2.0;
// The 'world' exists between -0.5 - 0.5 in X-Y plane.
// To convert to screen space, we translate by 0.5, scale to canvas size,
// and invert the Y-axis.
let world_to_screen =
Matrix4x4::scaling(w as f32, -h as f32, 1.0) * Matrix4x4::translate(0.5, -0.5, 0.);
for _ in 0..12 {
let x = (h_w + h_w * p.x) as usize;
// Y-axis is 0 at the top, and h at the bottom, flip it.
let y = (h - (h_h + h_h * p.y)) as usize;
draw_dot(&mut c, x, y);
let canvas_pixel = world_to_screen * p;
draw_dot(&mut c, canvas_pixel.x as usize, canvas_pixel.y as usize);
p = rot_hour * p;
}