bendn's repos / fimg
fast image operations
Diffstat (limited to 'src/drawing/tri.rs')
-rw-r--r--src/drawing/tri.rs67
1 files changed, 67 insertions, 0 deletions
diff --git a/src/drawing/tri.rs b/src/drawing/tri.rs
new file mode 100644
index 0000000..7ca13b6
--- /dev/null
+++ b/src/drawing/tri.rs
@@ -0,0 +1,67 @@
+//! trongle drawing
+use umath::Float;
+use vecto::Vector2;
+
+use crate::Image;
+use std::cmp::{max, min};
+
+impl<T: AsMut<[u8]> + AsRef<[u8]>, const CHANNELS: usize> Image<T, CHANNELS> {
+ /// Draw a (filled) triangle
+ /// ```
+ /// # use fimg::*;
+ /// let mut a = Image::alloc(10, 10);
+ /// // draw a triangle
+ /// a.as_mut().tri::<f32>(
+ /// (3.0, 2.0), // point a
+ /// (8.0, 7.0), // point b
+ /// (1.0, 8.0), // point c
+ /// [255] // white
+ /// );
+ /// # assert_eq!(a.buffer(), b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00");
+ /// ```
+ pub fn tri<F: Float<f32>>(
+ &mut self,
+ a: impl Into<Vector2<F>>,
+ b: impl Into<Vector2<F>>,
+ c: impl Into<Vector2<F>>,
+ col: [u8; CHANNELS],
+ ) {
+ let Vector2 {
+ x: mut x1,
+ y: mut y1,
+ } = a.into();
+ let Vector2 {
+ x: mut x2,
+ y: mut y2,
+ } = b.into();
+ let Vector2 { x: x3, y: y3 } = c.into();
+ // fix winding
+ if (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1) > 0.0 {
+ std::mem::swap(&mut x1, &mut x2);
+ std::mem::swap(&mut y1, &mut y2);
+ }
+ let ymin = max(y1.min(y2).min(y3).take() as u32, 0);
+ let ymax = min(y1.max(y2).max(y3).take() as u32, self.height());
+ let xmin = max(x1.min(x2).min(x3).take() as u32, 0);
+ let xmax = min(x1.max(x2).max(x3).take() as u32, self.width());
+ for y in ymin..ymax {
+ for x in xmin..xmax {
+ // algorithm from https://web.archive.org/web/20050408192410/http://sw-shader.sourceforge.net/rasterizer.html, but im too dumb to implement the faster ones
+ // SAFETY: nNaN
+ if unsafe {
+ (x1 - x2) * (F::new(y as f32) - y1) + (-(y1 - y2) * (F::new(x as f32) - x1))
+ > 0.
+ && (x2 - x3) * (F::new(y as f32) - y2)
+ + (-(y2 - y3) * (F::new(x as f32) - x2))
+ > 0.
+ && (x3 - x1) * (F::new(y as f32) - y3)
+ + (-(y3 - y1) * (F::new(x as f32) - x3))
+ > 0.
+ } {
+ // SAFETY: x, y are bounded
+ unsafe { self.set_pixel(x, y, &col) };
+ }
+ }
+ }
+ }
+}