Function prepare

src/renderers/createGridRenderer.ts:193–275

(gridArea, lineCountOrOptions)

  };

  const prepare: GridRenderer['prepare'] = (gridArea, lineCountOrOptions) => {
    assertNotDisposed();

    const isOptionsObject =
      lineCountOrOptions != null &&
      typeof lineCountOrOptions === 'object' &&
      ('lineCount' in lineCountOrOptions || 'color' in lineCountOrOptions);

    const options: GridPrepareOptions | undefined = isOptionsObject
      ? (lineCountOrOptions as GridPrepareOptions)
      : undefined;

    const lineCount: GridLineCount | undefined = isOptionsObject
      ? options?.lineCount
      : (lineCountOrOptions as GridLineCount | undefined);

    const horizontal = lineCount?.horizontal ?? DEFAULT_HORIZONTAL_LINES;
    const vertical = lineCount?.vertical ?? DEFAULT_VERTICAL_LINES;
    const colorString = options?.color ?? DEFAULT_GRID_COLOR;

    // Validate inputs
    if (horizontal < 0 || vertical < 0) {
      throw new Error('GridRenderer.prepare: line counts must be non-negative.');
    }
    if (
      !Number.isFinite(gridArea.left) ||
      !Number.isFinite(gridArea.right) ||
      !Number.isFinite(gridArea.top) ||
      !Number.isFinite(gridArea.bottom) ||
      !Number.isFinite(gridArea.canvasWidth) ||
      !Number.isFinite(gridArea.canvasHeight)
    ) {
      throw new Error('GridRenderer.prepare: gridArea dimensions must be finite numbers.');
    }
    if (gridArea.canvasWidth <= 0 || gridArea.canvasHeight <= 0) {
      throw new Error('GridRenderer.prepare: canvas dimensions must be positive.');
    }

    // Early return if no lines to draw
    if (horizontal === 0 && vertical === 0) {
      vertexCount = 0;
      return;
    }

    // Generate vertices
    const vertices = generateGridVertices(gridArea, horizontal, vertical);
    const requiredSize = vertices.byteLength;

    // Ensure minimum buffer size of 4 bytes
    const bufferSize = Math.max(4, requiredSize);

    // Create or recreate vertex buffer if needed
    if (!vertexBuffer || vertexBuffer.size < bufferSize) {
      if (vertexBuffer) {
        try {
          vertexBuffer.destroy();
        } catch {
          // best-effort