feat: implement canvas

Memola/Canvas/RenderPasses/EraserRenderPass.swift

@@ -0,0 +1,45 @@
+//
+//  EraserRenderPass.swift
+//  Memola
+//
+//  Created by Dscyre Scotti on 5/4/24.
+//
+
+import MetalKit
+import Foundation
+
+class EraserRenderPass: RenderPass {
+    var label: String = "Eraser Render Pass"
+
+    var descriptor: MTLRenderPassDescriptor?
+
+    var eraserPipelineState: MTLRenderPipelineState?
+
+    var stroke: Stroke?
+    weak var graphicTexture: MTLTexture?
+
+    init(renderer: Renderer) {
+        eraserPipelineState = PipelineStates.createEraserPipelineState(from: renderer)
+    }
+
+    func resize(on view: MTKView, to size: CGSize, with renderer: Renderer) { }
+
+    func draw(on canvas: Canvas, with renderer: Renderer) {
+        guard let descriptor else { return }
+
+        guard let commandBuffer = renderer.commandQueue.makeCommandBuffer() else { return }
+        commandBuffer.label = "Eraser Command Buffer"
+
+        guard let renderEncoder = commandBuffer.makeRenderCommandEncoder(descriptor: descriptor) else { return }
+        renderEncoder.label = label
+
+        guard let eraserPipelineState else { return }
+        renderEncoder.setRenderPipelineState(eraserPipelineState)
+
+        canvas.setUniformsBuffer(device: renderer.device, renderEncoder: renderEncoder)
+        stroke?.draw(device: renderer.device, renderEncoder: renderEncoder)
+
+        renderEncoder.endEncoding()
+        commandBuffer.commit()
+    }
+}