[g-canvas] 相机旋转时脏矩形渲染擦除区域有误

[xiaoiver]

计算得到的脏矩形四个顶点处于 Canvas 坐标系下，需要转换到 Viewport 坐标系下：

const dirtyRect = this.convertAABB2Rect(dirtyRenderBounds);
const { x, y, width, height } = dirtyRect;

// 转换到 viewport 坐标系
const tl = vec3.transformMat4(this.vec3a, vec3.fromValues(x, y, 0), this.vpMatrix);
const tr = vec3.transformMat4(this.vec3b, vec3.fromValues(x + width, y, 0), this.vpMatrix);
const bl = vec3.transformMat4(this.vec3c, vec3.fromValues(x, y + height, 0), this.vpMatrix);
const br = vec3.transformMat4(
  this.vec3d,
  vec3.fromValues(x + width, y + height, 0),
  this.vpMatrix,
);

// 重新计算该坐标系下四个顶点
const ix = Math.floor(minx);
const iy = Math.floor(miny);
const iwidth = Math.ceil(maxx - minx);
const iheight = Math.ceil(maxy - miny);

// 擦除脏矩形
context.save();
this.clearRect(context, ix, iy, iwidth, iheight);