ringbuffer for cycling healthy display points.

modules/demo/particles-maplibre/src/ringbuffer.ts

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+// Copyright (c) 2023, NVIDIA CORPORATION.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import regl from 'regl';
+
+export class ReglRingBuffer {
+  private buffer: regl.Buffer;
+  private head: number;
+  private bufferSize: number;
+
+  constructor(instance: regl.Regl, size: number) {
+    this.bufferSize = size;
+    this.buffer     = instance.buffer({
+      usage: 'dynamic',
+      type: 'float',
+      length: size * 4 * 2,
+    });
+    this.head       = 0;
+  }
+
+  write(newData: Float32Array): void {
+    const size = newData.length;
+    if (size > this.bufferSize) {
+      throw new Error(
+        `Single write of ${size} elements cannot exceed RingBuffer size ${this.bufferSize}`);
+    }
+    if (this.head === this.bufferSize) { this.head = 0; }
+
+    if (this.head + size > this.bufferSize) {
+      const left = this.bufferSize - this.head;
+      this.buffer.subdata(newData.slice(0, left), this.head);
+      this.buffer.subdata(newData.slice(left), 0);
+      this.head = (this.head + size) % this.bufferSize;
+    } else {
+      this.buffer.subdata(newData, this.head);
+      this.head += size;
+    }
+  }
+
+  get(): regl.Buffer { return this.buffer; }
+
+  destroy(): void { this.buffer.destroy(); }
+}