1 files changed, 49 insertions, 0 deletions
diff --git a/apps/web/src/services/renderer/webgl/webgl-context.ts b/apps/web/src/services/renderer/webgl/webgl-context.ts
new file mode 100644
index 00000000..aeefc503
--- /dev/null
+++ b/apps/web/src/services/renderer/webgl/webgl-context.ts
@@ -0,0 +1,49 @@
+import { createOffscreenCanvas } from "../canvas-utils";
+
+let gl: WebGLRenderingContext | null = null;
+let webglCanvas: OffscreenCanvas | HTMLCanvasElement | null = null;
+const programCache = new Map<string, WebGLProgram>();
+
+export function getWebGLContext({
+	width,
+	height,
+}: {
+	width: number;
+	height: number;
+}): {
+	context: WebGLRenderingContext;
+	programCache: Map<string, WebGLProgram>;
+} {
+	if (!webglCanvas) {
+		webglCanvas = createOffscreenCanvas({ width, height });
+		gl = webglCanvas.getContext("webgl", {
+			premultipliedAlpha: false,
+		}) as WebGLRenderingContext | null;
+		if (!gl) throw new Error("WebGL not supported");
+	}
+	if (webglCanvas.width !== width || webglCanvas.height !== height) {
+		webglCanvas.width = width;
+		webglCanvas.height = height;
+	}
+	if (!gl) throw new Error("WebGL context lost");
+	return { context: gl, programCache };
+}
+
+export function readResult({
+	width,
+	height,
+}: {
+	width: number;
+	height: number;
+}): OffscreenCanvas | HTMLCanvasElement {
+	if (!webglCanvas) throw new Error("WebGL canvas not initialized");
+	const outputCanvas = createOffscreenCanvas({ width, height });
+	const outputCtx = outputCanvas.getContext("2d") as
+		| CanvasRenderingContext2D
+		| OffscreenCanvasRenderingContext2D
+		| null;
+	if (outputCtx) {
+		outputCtx.drawImage(webglCanvas, 0, 0, width, height);
+	}
+	return outputCanvas;
+}