示例#1
0
func (q *commandQueue) Flush(context *opengl.Context) error {
	q.m.Lock()
	defer q.m.Unlock()
	// glViewport must be called at least at every frame on iOS.
	context.ResetViewportSize()
	for _, g := range q.commandGroups() {
		n := 0
		for _, c := range g {
			switch c := c.(type) {
			case *drawImageCommand:
				n += len(c.vertices)
			}
		}
		vertices := make([]float32, 0, n)
		for _, c := range g {
			switch c := c.(type) {
			case *drawImageCommand:
				vertices = append(vertices, c.vertices...)
			}
		}
		if 0 < len(vertices) {
			context.BufferSubData(opengl.ArrayBuffer, vertices)
		}
		// NOTE: WebGL doesn't seem to have Check gl.MAX_ELEMENTS_VERTICES or gl.MAX_ELEMENTS_INDICES so far.
		// Let's use them to compare to len(quads) in the future.
		if maxQuads < len(vertices)*opengl.Float.SizeInBytes()/QuadVertexSizeInBytes() {
			return fmt.Errorf("len(quads) must be equal to or less than %d", maxQuads)
		}
		numc := len(g)
		indexOffsetInBytes := 0
		for _, c := range g {
			if err := c.Exec(context, indexOffsetInBytes); err != nil {
				return err
			}
			if c, ok := c.(*drawImageCommand); ok {
				n := len(c.vertices) * opengl.Float.SizeInBytes() / QuadVertexSizeInBytes()
				indexOffsetInBytes += 6 * n * 2
			}
		}
		if 0 < numc {
			// Call glFlush to prevent black flicking (especially on Android (#226) and iOS).
			context.Flush()
		}
	}
	q.commands = []command{}
	return nil
}