1 files changed, 69 insertions, 0 deletions
diff --git a/camera.h b/camera.h
new file mode 100644
index 0000000..0dad35d
--- /dev/null
+++ b/camera.h
@@ -0,0 +1,69 @@
+mat4 camera_get_view_mat(camera_t camera)
+{
+	mat4 view = mat4_make_transl(v3_inv(camera.position));
+	view = mat4_rotate(view, camera.angles);
+	return view;
+}
+
+void camera_get_vecs(camera_t camera, v3 *left, v3 *up, v3 *front)
+{
+	f32 angle = deg2rad(camera.angles.x);
+	f32 cp = fcos(angle);
+	f32 sp = fsin(angle);
+
+	angle = deg2rad(camera.angles.y);
+	f32 cy = fcos(angle);
+	f32 sy = fsin(angle);
+
+	angle = deg2rad(camera.angles.z);
+	f32 cr = fcos(angle);
+	f32 sr = fsin(angle);
+
+	*left = (v3){cy*cr, -cy*sr, sy};
+	*up = (v3){sp*sy*cr+cp*sr, -sp*sy*sr+cp*cr, -sp*cy};
+	*front = (v3){-cp*sy*cr+sp*sr, cp*sy*sr+sp*cr, cp*cy};
+}
+
+mat4 camera_lookat(camera_t camera, v3 target, v3 world_up)
+{
+	v3 front = v3_norm(v3_sub(camera.position, target));
+	v3 right = v3_norm(v3_cross(world_up, front));
+	v3 up = v3_cross(front, right);
+
+	mat4 translate = mat4_make_transl(v3_inv(camera.position));
+	mat4 rotate = mat4_transp(mat4_make_rotate(right, up, front));
+	mat4 result = mat4_mul(rotate, translate);
+
+	return result;
+}
+
+mat4 ortho(f32 l, f32 r, f32 b, f32 t, f32 n, f32 f)
+{
+	mat4 ortho = MAT4_IDENTITY;
+	ortho.c0.x = 2.0f/(r-l);
+	ortho.c1.y = 2.0f/(t-b);
+	ortho.c2.z = -2.0f/(f-n);
+	ortho.c3.x = -(r+l)/(r-l);
+	ortho.c3.y = -(t+b)/(t-b);
+	ortho.c3.z = -(f+n)/(f-n);
+	return ortho;
+}
+
+mat4 perspective(camera_t camera, f32 aspect_ratio)
+{
+	f32 n = camera.near;
+	f32 f = camera.far;
+
+	f32 r = n*ftan(deg2rad(camera.fov/2.0f));
+	f32 t = r/aspect_ratio;
+
+	mat4 perspective = MAT4_IDENTITY;
+	perspective.c0.x = n/r;
+	perspective.c1.y = n/t;
+	perspective.c2.z = -(f+n)/(f-n);
+	perspective.c2.w = -1.0f;
+	perspective.c3.z = (-2.0f*f*n)/(f-n);
+	perspective.c3.w = 0.0f;
+
+	return perspective;
+}