From 24b33f8146c245a7e7aa28ffcd812a8cb536e6c3 Mon Sep 17 00:00:00 2001
From: numzero <numzer0@yandex.ru>
Date: Sun, 22 Sep 2024 15:41:05 +0300
Subject: [PATCH] Basic camera control

---
 src/bin/wireframe/main.rs | 46 +++++++++++++++++++++++++++++----------
 1 file changed, 35 insertions(+), 11 deletions(-)

diff --git a/src/bin/wireframe/main.rs b/src/bin/wireframe/main.rs
index e68cced..b6cdd8f 100644
--- a/src/bin/wireframe/main.rs
+++ b/src/bin/wireframe/main.rs
@@ -1,4 +1,4 @@
-use glam::{mat4, vec2, vec3, vec4, Mat4, Vec3};
+use glam::{mat4, vec2, vec3, vec4, Mat4, Quat, Vec3};
 use glium::{
 	backend::glutin::SimpleWindowBuilder,
 	implement_vertex, uniform,
@@ -40,7 +40,9 @@ fn main() {
 	];
 	let vertex_buffer = VertexBuffer::new(&display, &shape).unwrap();
 
-	let mut t: f32 = -0.5;
+	let mut cur_pos = vec2(0., 0.);
+	let mut drag_start = None;
+	let mut cam_rot = Quat::IDENTITY;
 
 	#[allow(deprecated)]
 	event_loop
@@ -52,19 +54,12 @@ fn main() {
 						* std::f32::consts::SQRT_2;
 					let proj = make_proj_matrix(vec3(size.x, size.y, 2.), (0.125, 1024.125));
 
-					t += 0.02;
-					let x = t.sin() * 0.5;
-					let mdl = mat4(
-						vec4(1., 0., 0., 0.),
-						vec4(0., 1., 0., 0.),
-						vec4(0., 0., 1., 0.),
-						vec4(x, 0., 0., 1.),
-					);
+					let view = Mat4::from_quat(cam_rot);
 
 					let mut target = display.draw();
 					target.clear_color(0.0, 0.0, 0.2, 1.0);
 
-					let mvp = proj * mdl;
+					let mvp = proj * view;
 					let uniforms = uniform! {
 						mvp: mvp.to_cols_array_2d(),
 					};
@@ -81,6 +76,35 @@ fn main() {
 					target.finish().unwrap();
 				}
 
+				WindowEvent::MouseInput {
+					device_id: _,
+					state,
+					button,
+				} => match button {
+					winit::event::MouseButton::Left => match state {
+						winit::event::ElementState::Pressed => {
+							drag_start = Some((cur_pos, cam_rot))
+						}
+						winit::event::ElementState::Released => drag_start = None,
+					},
+					_ => {}
+				},
+
+				WindowEvent::CursorMoved {
+					device_id: _,
+					position,
+				} => {
+					let size = window.inner_size();
+					let size = vec2(size.width as f32, size.height as f32);
+					cur_pos = vec2(position.x as f32, position.y as f32) / size;
+					if let Some((drag_start, drag_init_rot)) = drag_start {
+						let offset = cur_pos - drag_start;
+						cam_rot = Quat::from_euler(glam::EulerRot::YXZ, offset.x, offset.y, 0.)
+							* drag_init_rot;
+						window.request_redraw();
+					}
+				}
+
 				WindowEvent::Resized(window_size) => {
 					display.resize(window_size.into());
 				}