From 832daefbda9d912eafbebfa2fffa157e7e8e2d6a Mon Sep 17 00:00:00 2001
From: gered <gered@blarg.ca>
Date: Fri, 31 Mar 2023 23:27:15 -0400
Subject: [PATCH] add initial triangle_2d_textured method

---
 ggdt/benches/triangles.rs             | 16 ++++++++++++++++
 ggdt/src/graphics/bitmap/triangles.rs | 25 +++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/ggdt/benches/triangles.rs b/ggdt/benches/triangles.rs
index 60b0e86..ac06fce 100644
--- a/ggdt/benches/triangles.rs
+++ b/ggdt/benches/triangles.rs
@@ -7,6 +7,8 @@ pub fn criterion_benchmark(c: &mut Criterion) {
 	let height = 240;
 
 	let mut dest = IndexedBitmap::new(width, height).unwrap();
+	let (texture, _palette) =
+		IndexedBitmap::load_gif_file(std::path::Path::new("./test-assets/gif/small.gif")).unwrap();
 
 	c.bench_function("indexedbitmap_triangle_2d_solid_color", |b| {
 		b.iter(|| {
@@ -18,6 +20,20 @@ pub fn criterion_benchmark(c: &mut Criterion) {
 			);
 		})
 	});
+
+	c.bench_function("indexedbitmap_triangle_2d_textured", |b| {
+		b.iter(|| {
+			dest.triangle_2d_textured(
+				black_box(Vector2::new(47.0, 23.0)),
+				black_box(Vector2::new(0.0, 0.0)),
+				black_box(Vector2::new(60.0, 192.0)),
+				black_box(Vector2::new(1.0, 0.0)),
+				black_box(Vector2::new(280.0, 153.0)),
+				black_box(Vector2::new(1.0, 1.0)),
+				black_box(&texture),
+			);
+		})
+	});
 }
 
 criterion_group!(benches, criterion_benchmark);
diff --git a/ggdt/src/graphics/bitmap/triangles.rs b/ggdt/src/graphics/bitmap/triangles.rs
index b0dfd89..f714eeb 100644
--- a/ggdt/src/graphics/bitmap/triangles.rs
+++ b/ggdt/src/graphics/bitmap/triangles.rs
@@ -19,6 +19,31 @@ impl<PixelType: Pixel> Bitmap<PixelType> {
 		)
 	}
 
+	pub fn triangle_2d_textured(
+		&mut self,
+		a: Vector2,
+		a_tex: Vector2,
+		b: Vector2,
+		b_tex: Vector2,
+		c: Vector2,
+		c_tex: Vector2,
+		texture: &Bitmap<PixelType>,
+	) {
+		let texture_width = texture.width() as f32;
+		let texture_height = texture.height() as f32;
+		let inverse_area = 1.0 / cross(a, b, c); // inverting to avoid division
+		self.triangle_2d_custom(
+			a, //
+			b,
+			c,
+			|dest_pixels, w0, w1, w2| {
+				let u = (w0 * a_tex.x + w1 * b_tex.x + w2 * c_tex.x) * inverse_area * texture_width;
+				let v = (w0 * a_tex.y + w1 * b_tex.y + w2 * c_tex.y) * inverse_area * texture_height;
+				*dest_pixels = unsafe { texture.get_pixel_unchecked(u as i32, v as i32) };
+			},
+		)
+	}
+
 	#[inline]
 	pub fn triangle_2d_custom(
 		&mut self,