From ae44478b30d890fe0fb04022f44d474dcdcc3f9d Mon Sep 17 00:00:00 2001
From: Lassi Pulkkinen <lassi@pulk.fi>
Date: Thu, 31 Oct 2024 03:11:21 +0200
Subject: Initial commit (import old repo)

---
 glm/camera.ha | 71 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)
 create mode 100644 glm/camera.ha

(limited to 'glm/camera.ha')

diff --git a/glm/camera.ha b/glm/camera.ha
new file mode 100644
index 0000000..b648232
--- /dev/null
+++ b/glm/camera.ha
@@ -0,0 +1,71 @@
+use math;
+
+export fn ortho(
+	m: *m4,
+	left: f32,
+	right: f32,
+	bottom: f32,
+	top: f32,
+	znear: f32,
+	zfar: f32,
+) void = {
+	m4_set_zero(m);
+
+	const rl = 1.0 / (right - left);
+	const tb = 1.0 / (top - bottom);
+	const nf = -1.0 / (zfar - znear);
+
+	m[0][0] = 2.0 * rl;
+	m[1][1] = 2.0 * tb;
+	m[2][2] = 2.0 * nf;
+	m[3][0] =-(right + left) * rl;
+	m[3][1] =-(top + bottom) * tb;
+	m[3][2] = (zfar + znear) * nf;
+	m[3][3] = 1.0;
+};
+
+export fn lookat(eye: *v3, center: *v3, up: *v3) m4 = {
+	const f = v3_sub(center, eye);
+	v3_normalize(&f);
+	const s = v3_crossn(&f, up);
+	const u = v3_cross(&s, &f);
+
+	const res = m4_new(1.0);
+	res[0][0] = s[0];
+	res[0][1] = u[0];
+	res[0][2] = -f[0];
+	res[1][0] = s[1];
+	res[1][1] = u[1];
+	res[1][2] = -f[1];
+	res[2][0] = s[2];
+	res[2][1] = u[2];
+	res[2][2] = -f[2];
+	res[3][0] = -v3_dot(&s, eye);
+	res[3][1] = -v3_dot(&u, eye);
+	res[3][2] = v3_dot(&f, eye);
+	res[0][3] = 0.0;
+	res[1][3] = 0.0;
+	res[2][3] = 0.0;
+	res[3][3] = 1.0;
+	return res;
+};
+
+
+export fn perspective(
+	m: *m4,
+	fovy_in_deg: f32,
+	aspect_ratio: f32,
+	znear: f32,
+	zfar: f32
+) void = {
+	m4_set_zero(m);
+
+	const f = 1.0 / math::tanf64(fovy_in_deg * 0.5): f32;
+	const f1 = 1.0 / (znear - zfar);
+
+	m[0][0] = f / aspect_ratio;
+	m[1][1] = f;
+	m[2][2] = (znear + zfar) * f1;
+	m[2][3] = -1.0;
+	m[3][2] = 2.0 * znear * zfar * f1;
+};
-- 
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