1 files changed, 54 insertions, 26 deletions

diff --git a/src/renderer.rs b/src/renderer.rs
index a15015b..a86b05b 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -1,4 +1,4 @@
-use std::{convert::TryInto, num::NonZeroU32};
+use std::{convert::TryInto, mem::size_of, num::NonZeroU32};
 
 use crate::{instance::InstanceId, vertex::SQUARE, Instance, RenderWindowConfig, Vertex};
 use pollster::FutureExt;
@@ -45,6 +45,8 @@ pub struct Renderer {
 	render_pipeline: wgpu::RenderPipeline,
 	square_vertex_buffer: wgpu::Buffer,
 	square_vertices: u32,
+	instance_buffer: wgpu::Buffer,
+	instance_buffer_size: usize,
 	instances: Vec<Instance>,
 	window: Window,
 }
@@ -114,6 +116,21 @@ impl Renderer {
 		})
 	}
 
+	fn new_instance_buffer(
+		device: &wgpu::Device,
+		instances: &Vec<Instance>,
+	) -> (wgpu::Buffer, usize) {
+		let instance_buffer_size = instances.capacity();
+		let instance_buffer = device.create_buffer(&wgpu::BufferDescriptor {
+			label: Some("Sprite Instance Buffer"),
+			size: (instance_buffer_size * size_of::<Instance>()) as wgpu::BufferAddress,
+			usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
+			mapped_at_creation: false,
+		});
+
+		(instance_buffer, instance_buffer_size)
+	}
+
 	/// Initializes the renderer
 	///
 	/// # Errors
@@ -180,7 +197,10 @@ impl Renderer {
 			usage: wgpu::BufferUsages::VERTEX,
 		});
 
+		// create the instance buffer
 		let instances = Vec::with_capacity(config.instance_capacity);
+		let (instance_buffer, instance_buffer_size) =
+			Self::new_instance_buffer(&device, &instances);
 
 		Ok(Self {
 			surface,
@@ -191,6 +211,8 @@ impl Renderer {
 			render_pipeline,
 			square_vertex_buffer,
 			square_vertices,
+			instance_buffer,
+			instance_buffer_size,
 			instances,
 			window,
 		})
@@ -231,6 +253,23 @@ impl Renderer {
 		self.window.set_title(title);
 	}
 
+	fn expand_instance_buffer(&mut self) {
+		(self.instance_buffer, self.instance_buffer_size) =
+			Self::new_instance_buffer(&self.device, &self.instances);
+	}
+
+	fn fill_instance_buffer(&mut self) {
+		if self.instances.len() > self.instance_buffer_size {
+			self.expand_instance_buffer();
+		}
+
+		self.queue.write_buffer(
+			&self.instance_buffer,
+			0 as wgpu::BufferAddress,
+			bytemuck::cast_slice(&self.instances),
+		);
+	}
+
 	/// Add an instance to the renderer, and returns an `InstanceId` to the
 	/// instance. This id becomes invalid if the instances are cleared.
 	pub fn push_instance(&mut self, instance: Instance) -> InstanceId {
@@ -270,18 +309,12 @@ impl Renderer {
 				label: Some("Render Encoder"),
 			});
 
+		self.fill_instance_buffer();
 		let num_instances = self
 			.instances
 			.len()
 			.try_into()
 			.expect("expected less than 3 billion instances");
-		let instance_buffer = self
-			.device
-			.create_buffer_init(&wgpu::util::BufferInitDescriptor {
-				label: Some("Sprite Instance Buffer"),
-				contents: bytemuck::cast_slice(&self.instances),
-				usage: wgpu::BufferUsages::VERTEX,
-			});
 
 		{
 			let mut render_pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
@@ -299,7 +332,7 @@ impl Renderer {
 
 			render_pass.set_pipeline(&self.render_pipeline);
 			render_pass.set_vertex_buffer(0, self.square_vertex_buffer.slice(..));
-			render_pass.set_vertex_buffer(1, instance_buffer.slice(..));
+			render_pass.set_vertex_buffer(1, self.instance_buffer.slice(..));
 			render_pass.draw(0..self.square_vertices, 0..num_instances);
 		}
 		// the encoder can't finish building the command buffer until the
@@ -325,26 +358,21 @@ impl Renderer {
 					}
 				}
 			}
-			Event::RedrawRequested(window_id) => {
-				if window_id == self.window.id() {
-					match self.render() {
-						Ok(_) => {}
-						// reconfigure the surface if it's been lost
-						Err(wgpu::SurfaceError::Lost) => {
-							self.reconfigure();
-						}
-						// if we ran out of memory, then we'll die
-						Err(wgpu::SurfaceError::OutOfMemory) => {
-							*control_flow = ControlFlow::ExitWithCode(1);
-						}
-						// otherwise, we'll just log the error
-						Err(e) => log::error!("{}", e),
+			Event::MainEventsCleared => {
+				match self.render() {
+					Ok(_) => {}
+					// reconfigure the surface if it's been lost
+					Err(wgpu::SurfaceError::Lost) => {
+						self.reconfigure();
+					}
+					// if we ran out of memory, then we'll die
+					Err(wgpu::SurfaceError::OutOfMemory) => {
+						*control_flow = ControlFlow::ExitWithCode(1);
 					}
+					// otherwise, we'll just log the error
+					Err(e) => log::error!("{}", e),
 				}
 			}
-			Event::MainEventsCleared => {
-				self.window.request_redraw();
-			}
 			_ => {}
 		})
 	}