From cd7d74507fa54d026547b7dda9e1498a81a395b5 Mon Sep 17 00:00:00 2001
From: Micha White <botahamec@outlook.com>
Date: Sun, 18 Sep 2022 18:16:19 -0400
Subject: An actual instancing API

---
 src/renderer.rs | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

(limited to 'src/renderer.rs')

diff --git a/src/renderer.rs b/src/renderer.rs
index 75e6d1e..81e1a3f 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -1,6 +1,6 @@
 use std::convert::TryInto;
 
-use crate::{vertex::SQUARE, Instance, RenderWindowConfig, Vertex};
+use crate::{instance::InstanceId, vertex::SQUARE, Instance, RenderWindowConfig, Vertex};
 use pollster::FutureExt;
 use thiserror::Error;
 use wgpu::{include_wgsl, util::DeviceExt};
@@ -172,7 +172,7 @@ impl Renderer {
 			usage: wgpu::BufferUsages::VERTEX,
 		});
 
-		let instances = Vec::new();
+		let instances = Vec::with_capacity(config.instance_capacity);
 
 		Ok(Self {
 			surface,
@@ -199,6 +199,24 @@ impl Renderer {
 		self.surface.configure(&self.device, &self.surface_config);
 	}
 
+	/// 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 {
+		let index = self.instances.len();
+		self.instances.push(instance);
+		InstanceId(index)
+	}
+
+	/// Get a mutable reference to an instance
+	pub fn instance_mut(&mut self, id: InstanceId) -> Option<&mut Instance> {
+		self.instances.get_mut(id.0)
+	}
+
+	/// Clears the list of instances, making all instance ID's invalid
+	pub fn clear_instances(&mut self) {
+		self.instances.clear();
+	}
+
 	/// Renders a new frame to the window
 	///
 	/// # Errors
-- 
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