fast image operations
| -rw-r--r-- | src/drawing/mod.rs | 3 | ||||
| -rw-r--r-- | src/drawing/tri.rs | 45 |
2 files changed, 47 insertions, 1 deletions
diff --git a/src/drawing/mod.rs b/src/drawing/mod.rs index 18bbc5d..8437083 100644 --- a/src/drawing/mod.rs +++ b/src/drawing/mod.rs @@ -1,2 +1,3 @@ -//! contains drawing operations, like line drawing +//! contains drawing operations, like line drawing and triangle drawing mod line; +mod tri; diff --git a/src/drawing/tri.rs b/src/drawing/tri.rs new file mode 100644 index 0000000..3cc390b --- /dev/null +++ b/src/drawing/tri.rs @@ -0,0 +1,45 @@ +//! trongle drawing +use crate::Image; + +impl<const CHANNELS: usize> Image<&mut [u8], CHANNELS> { + /// Draw a (filled) triangle + /// + /// # Safety + /// + /// UB if any point is out of bounds + /// ``` + /// # use fimg::*; + /// let mut a = Image::alloc(10, 10); + /// // draw a triangle from point a v point b v point c v + /// // with color white + /// unsafe { a.as_mut().tri((3.0, 2.0), (8.0, 7.0), (1.0, 8.0), [255]) }; + /// # 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\xff\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\x00\x00\x00\x00\x00\x00\x00\xff\xff\xff\xff\x00\x00\x00\x00\x00\xff\xff\xff\xff\xff\xff\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 unsafe fn tri( + &mut self, + (x1, y1): (f32, f32), + (x2, y2): (f32, f32), + (x3, y3): (f32, f32), + c: [u8; CHANNELS], + ) { + // TODO optimize + for y in y1.min(y2).min(y3) as u32..y1.max(y2).max(y3) as u32 { + for x in x1.min(x2).min(x3) as u32..x1.max(x2).max(x3) as u32 { + let s = (x1 - x3) * (y as f32 - y3) - (y1 - y2) * (x as f32 - x3); + let t = (x2 - x1) * (y as f32 - y1) - (y2 - y1) * (x as f32 - x1); + + if (s < 0.0) != (t < 0.0) && s != 0.0 && t != 0.0 { + continue; + } + + let d = (x3 - x2) * (y as f32 - y2) - (y3 - y2) * (x as f32 - x2); + if d == 0.0 || (d < 0.0) == (s + t <= 0.0) { + // SAFETY: + // caller gurantees triangle is in bounds, this loops over the + // bounding box of the triangle, therefore this is fine. + unsafe { self.set_pixel(x, y, c) }; + } + } + } + } +} |