From d9e8b96754e5ca154835c7e9c65f745135ff742a Mon Sep 17 00:00:00 2001
From: Florian RICHER <florian.richer@unova.fr>
Date: Tue, 14 Jun 2022 13:08:10 +0200
Subject: [PATCH] [INSTANCE] Update instances

---
 engine_core/src/state.rs | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/engine_core/src/state.rs b/engine_core/src/state.rs
index e874d20..a7c53ca 100644
--- a/engine_core/src/state.rs
+++ b/engine_core/src/state.rs
@@ -35,6 +35,9 @@ const INSTANCE_DISPLACEMENT: cgmath::Vector3<f32> = cgmath::Vector3::new(
     NUM_INSTANCES_PER_ROW as f32 * 0.5,
 );
 
+const FRAME_TIME: f32 = 1.0 / 60.0;
+const ROTATION_SPEED: f32 = std::f32::consts::PI * FRAME_TIME * 0.5;
+
 pub struct State {
     pub surface: wgpu::Surface,
     pub device: wgpu::Device,
@@ -310,7 +313,7 @@ impl State {
         let instance_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
             label: Some("Instance Buffer"),
             contents: bytemuck::cast_slice(&instance_data),
-            usage: wgpu::BufferUsages::VERTEX,
+            usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
         });
 
         let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
@@ -418,6 +421,22 @@ impl State {
             0,
             bytemuck::cast_slice(&[self.camera_uniform]),
         );
+
+        for instance in &mut self.instances {
+            let amount = cgmath::Quaternion::from_angle_y(cgmath::Rad(ROTATION_SPEED));
+            let current = instance.rotation;
+            instance.rotation = amount * current;
+        }
+        let instance_data = self
+            .instances
+            .iter()
+            .map(super::instance::Instance::to_raw)
+            .collect::<Vec<_>>();
+        self.queue.write_buffer(
+            &self.instance_buffer,
+            0,
+            bytemuck::cast_slice(&instance_data),
+        );
     }
 
     pub fn render(&mut self) -> Result<(), wgpu::SurfaceError> {