[CAMERA] Add from tutorial

engine_core/src/camera.rs

@@ -0,0 +1,139 @@
+use winit::event::{WindowEvent, KeyboardInput, ElementState, VirtualKeyCode};
+
+#[rustfmt::skip]
+pub const OPENGL_TO_WGPU_MATRIX: cgmath::Matrix4<f32> = cgmath::Matrix4::new(
+    1.0, 0.0, 0.0, 0.0,
+    0.0, 1.0, 0.0, 0.0,
+    0.0, 0.0, 0.5, 0.0,
+    0.0, 0.0, 0.5, 1.0,
+);
+
+pub struct Camera {
+    pub eye: cgmath::Point3<f32>,
+    pub target: cgmath::Point3<f32>,
+    pub up: cgmath::Vector3<f32>,
+    pub aspect: f32,
+    pub fovy: f32,
+    pub znear: f32,
+    pub zfar: f32,
+}
+
+impl Camera {
+    fn build_view_projection_matrix(&self) -> cgmath::Matrix4<f32> {
+        let view = cgmath::Matrix4::look_at_rh(self.eye, self.target, self.up);
+        let proj = cgmath::perspective(cgmath::Deg(self.fovy), self.aspect, self.znear, self.zfar);
+
+        return OPENGL_TO_WGPU_MATRIX * proj * view;
+    }
+}
+
+// We need this for Rust to store our data correctly for the shaders
+#[repr(C)]
+// This is so we can store this in a buffer
+#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct CameraUniform {
+    // We can't use cgmath with bytemuck directly so we'll have
+    // to convert the Matrix4 into a 4x4 f32 array
+    view_proj: [[f32; 4]; 4],
+}
+
+impl CameraUniform {
+    pub fn new() -> Self {
+        use cgmath::SquareMatrix;
+        Self {
+            view_proj: cgmath::Matrix4::identity().into(),
+        }
+    }
+
+    pub fn update_view_proj(&mut self, camera: &Camera) {
+        self.view_proj = camera.build_view_projection_matrix().into();
+    }
+}
+
+pub struct CameraController {
+    speed: f32,
+    is_forward_pressed: bool,
+    is_backward_pressed: bool,
+    is_left_pressed: bool,
+    is_right_pressed: bool,
+}
+
+impl CameraController {
+    pub fn new(speed: f32) -> Self {
+        Self {
+            speed,
+            is_forward_pressed: false,
+            is_backward_pressed: false,
+            is_left_pressed: false,
+            is_right_pressed: false,
+        }
+    }
+
+    pub fn process_events(&mut self, event: &WindowEvent) -> bool {
+        match event {
+            WindowEvent::KeyboardInput {
+                input:
+                    KeyboardInput {
+                        state,
+                        virtual_keycode: Some(keycode),
+                        ..
+                    },
+                ..
+            } => {
+                let is_pressed = *state == ElementState::Pressed;
+                match keycode {
+                    VirtualKeyCode::W | VirtualKeyCode::Up => {
+                        self.is_forward_pressed = is_pressed;
+                        true
+                    }
+                    VirtualKeyCode::A | VirtualKeyCode::Left => {
+                        self.is_left_pressed = is_pressed;
+                        true
+                    }
+                    VirtualKeyCode::S | VirtualKeyCode::Down => {
+                        self.is_backward_pressed = is_pressed;
+                        true
+                    }
+                    VirtualKeyCode::D | VirtualKeyCode::Right => {
+                        self.is_right_pressed = is_pressed;
+                        true
+                    }
+                    _ => false,
+                }
+            }
+            _ => false,
+        }
+    }
+
+    pub fn update_camera(&self, camera: &mut Camera) {
+        use cgmath::InnerSpace;
+        let forward = camera.target - camera.eye;
+        let forward_norm = forward.normalize();
+        let forward_mag = forward.magnitude();
+
+        // Prevents glitching when camera gets too close to the
+        // center of the scene.
+        if self.is_forward_pressed && forward_mag > self.speed {
+            camera.eye += forward_norm * self.speed;
+        }
+        if self.is_backward_pressed {
+            camera.eye -= forward_norm * self.speed;
+        }
+
+        let right = forward_norm.cross(camera.up);
+
+        // Redo radius calc in case the fowrard/backward is pressed.
+        let forward = camera.target - camera.eye;
+        let forward_mag = forward.magnitude();
+
+        if self.is_right_pressed {
+            // Rescale the distance between the target and eye so
+            // that it doesn't change. The eye therefore still
+            // lies on the circle made by the target and eye.
+            camera.eye = camera.target - (forward + right * self.speed).normalize() * forward_mag;
+        }
+        if self.is_left_pressed {
+            camera.eye = camera.target - (forward - right * self.speed).normalize() * forward_mag;
+        }
+    }
+}

engine_core/src/lib.rs

@@ -1,6 +1,7 @@
 mod state;
 pub(self) mod vertex;
 pub(self) mod texture;
+pub(self) mod camera;
 
 use winit::{
     event::{ElementState, Event, KeyboardInput, VirtualKeyCode, WindowEvent},

engine_core/src/shader.wgsl

@@ -1,3 +1,9 @@
+struct CameraUniform {
+    view_proj: mat4x4<f32>;
+};
+[[group(1), binding(0)]]
+var<uniform> camera: CameraUniform;
+
 struct VertexInput {
     [[location(0)]] position: vec3<f32>;
     [[location(1)]] tex_coords: vec2<f32>;
@@ -14,7 +20,7 @@ fn vs_main(
 ) -> VertexOutput {
     var out: VertexOutput;
     out.tex_coords = model.tex_coords;
-    out.clip_position = vec4<f32>(model.position, 1.0);
+    out.clip_position = camera.view_proj * vec4<f32>(model.position, 1.0);
     return out;
 }
 

engine_core/src/state.rs

@@ -35,6 +35,11 @@ pub struct State {
     pub size: winit::dpi::PhysicalSize<u32>,
     render_pipeline: wgpu::RenderPipeline,
     vertex_buffer: wgpu::Buffer,
+    camera: super::camera::Camera,
+    camera_uniform: super::camera::CameraUniform,
+    camera_buffer: wgpu::Buffer,
+    camera_bind_group: wgpu::BindGroup,
+    camera_controller: super::camera::CameraController,
     // num_vertices: u32,
     index_buffer: wgpu::Buffer,
     num_indices: u32,
@@ -160,10 +165,64 @@ impl State {
             source: wgpu::ShaderSource::Wgsl(include_str!("shader.wgsl").into()),
         });
 
+        let camera = super::camera::Camera {
+            // position the camera one unit up and 2 units back
+            // +z is out of the screen
+            eye: (0.0, 1.0, 2.0).into(),
+            // have it look at the origin
+            target: (0.0, 0.0, 0.0).into(),
+            // which way is "up"
+            up: cgmath::Vector3::unit_y(),
+            aspect: config.width as f32 / config.height as f32,
+            fovy: 45.0,
+            znear: 0.1,
+            zfar: 100.0,
+        };
+
+        let mut camera_uniform = super::camera::CameraUniform::new();
+        camera_uniform.update_view_proj(&camera);
+
+        let camera_buffer = device.create_buffer_init(
+            &wgpu::util::BufferInitDescriptor {
+                label: Some("Camera Buffer"),
+                contents: bytemuck::cast_slice(&[camera_uniform]),
+                usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+            }
+        );
+
+        let camera_bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            entries: &[
+                wgpu::BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: wgpu::ShaderStages::VERTEX,
+                    ty: wgpu::BindingType::Buffer {
+                        ty: wgpu::BufferBindingType::Uniform,
+                        has_dynamic_offset: false,
+                        min_binding_size: None,
+                    },
+                    count: None,
+                }
+            ],
+            label: Some("camera_bind_group_layout"),
+        });
+
+        let camera_bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            layout: &camera_bind_group_layout,
+            entries: &[
+                wgpu::BindGroupEntry {
+                    binding: 0,
+                    resource: camera_buffer.as_entire_binding(),
+                }
+            ],
+            label: Some("camera_bind_group"),
+        });
+
+        let camera_controller = super::camera::CameraController::new(0.2);
+
         let render_pipeline_layout =
             device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                 label: Some("Render Pipeline Layout"),
-                bind_group_layouts: &[&texture_bind_group_layout],
+                bind_group_layouts: &[&texture_bind_group_layout, &camera_bind_group_layout],
                 push_constant_ranges: &[],
             });
 
@@ -203,7 +262,7 @@ impl State {
                 alpha_to_coverage_enabled: false,
             },
             multiview: None,
-        });
+        });        
 
         Self {
             surface,
@@ -213,6 +272,11 @@ impl State {
             size,
             render_pipeline,
             vertex_buffer,
+            camera,
+            camera_uniform,
+            camera_buffer,
+            camera_bind_group,
+            camera_controller,
             // num_vertices,
             index_buffer,
             num_indices,
@@ -230,12 +294,15 @@ impl State {
         }
     }
 
-    pub fn input(&mut self, _event: &WindowEvent) -> bool {
-        // log::info!("{:#?}", event);
-        false
+    pub fn input(&mut self, event: &WindowEvent) -> bool {
+        self.camera_controller.process_events(event)
     }
 
-    pub fn update(&mut self) {}
+    pub fn update(&mut self) {
+        self.camera_controller.update_camera(&mut self.camera);
+        self.camera_uniform.update_view_proj(&self.camera);
+        self.queue.write_buffer(&self.camera_buffer, 0, bytemuck::cast_slice(&[self.camera_uniform]));
+    }
 
     pub fn render(&mut self) -> Result<(), wgpu::SurfaceError> {
         let output = self.surface.get_current_texture()?;
@@ -273,6 +340,7 @@ impl State {
             render_pass.set_pipeline(&self.render_pipeline);
 
             render_pass.set_bind_group(0, &self.diffuse_bind_group, &[]);
+            render_pass.set_bind_group(1, &self.camera_bind_group, &[]);
             render_pass.set_vertex_buffer(0, self.vertex_buffer.slice(..));
             render_pass.set_index_buffer(self.index_buffer.slice(..), wgpu::IndexFormat::Uint16);
             // render_pass.draw(0..self.num_vertices, 0..1);