From e075667cd2dc878dd9dceb07c85719f6712bcda1 Mon Sep 17 00:00:00 2001
From: James Barnett <noreply@jamesbarnett.xyz>
Date: Sun, 2 Jan 2022 18:23:36 +0000
Subject: Implement multi-threaded rendering

---
 src/RaytraceDispatcher.ts | 70 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)
 create mode 100644 src/RaytraceDispatcher.ts

(limited to 'src/RaytraceDispatcher.ts')

diff --git a/src/RaytraceDispatcher.ts b/src/RaytraceDispatcher.ts
new file mode 100644
index 0000000..866d2d1
--- /dev/null
+++ b/src/RaytraceDispatcher.ts
@@ -0,0 +1,70 @@
+import {Colour} from './Colour';
+import {Framebuffer} from './Framebuffer';
+import {RaytraceContext} from './RaytraceContext';
+import {instanceToPlain} from 'class-transformer';
+import 'reflect-metadata';
+
+export class RaytraceDispatcher {
+  private renderStartMs: number;
+  private responsesReceived = 0;
+  constructor(
+    readonly framebuffer: Framebuffer,
+    readonly context: RaytraceContext
+  ) {
+    this.renderStartMs = new Date().getTime();
+  }
+
+  requestRender() {
+    // Assumes height and threads are always even
+    const rowBatchSize = this.context.height / this.context.options.numThreads;
+
+    for (let y = 0; y < this.context.height; y += rowBatchSize) {
+      const rowStartIndex = y;
+      const rowEndIndex = y + rowBatchSize - 1;
+      this.dispatchRaytraceWorker(rowStartIndex, rowEndIndex, this.context);
+    }
+  }
+
+  private dispatchRaytraceWorker(
+    rowStartIndex: number,
+    rowEndIndex: number,
+    context: RaytraceContext
+  ) {
+    console.log(
+      `Dispatching worker for lines ${rowStartIndex} to ${rowEndIndex}`
+    );
+
+    const raytracer = new Worker(new URL('./Raytracer.ts', import.meta.url));
+
+    raytracer.postMessage({
+      type: 'raytraceStart',
+      rowStartIndex: rowStartIndex,
+      rowEndIndex: rowEndIndex,
+      context: JSON.stringify(instanceToPlain(context)),
+    });
+
+    raytracer.onmessage = ({data}) => {
+      if (data.type === 'raytraceResultRow') {
+        this.processResponse(data.rowIndex, data.resultBuffer);
+      }
+      if (data.type === 'raytraceComplete') {
+        this.handleWorkerComplete();
+      }
+    };
+  }
+
+  private handleWorkerComplete() {
+    if (++this.responsesReceived === this.context.options.numThreads) {
+      console.log(
+        `Render completed in ${new Date().getTime() - this.renderStartMs}ms`
+      );
+    }
+  }
+
+  private processResponse(rowIndex: number, rowData: Colour[]) {
+    for (let x = 0; x < this.framebuffer.width; x++) {
+      this.framebuffer.writePixelAt(x, rowIndex, rowData[x]);
+    }
+    this.framebuffer.flush();
+  }
+}
-- 
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