func (c *runContext) render(g GraphicsContext) error {
fps := c.fps
n := now()
defer func() {
// Calc the current FPS.
if time.Second > time.Duration(n-c.lastFPSUpdated) {
return
}
currentFPS := float64(c.frames) * float64(time.Second) / float64(n-c.lastFPSUpdated)
c.updateFPS(currentFPS)
c.lastFPSUpdated = n
c.frames = 0
}()
// If lastUpdated is too old, we assume that screen is not shown.
if 10*int64(time.Second)/int64(fps) < n-c.lastUpdated {
c.lastUpdated = n
return nil
}
// Note that generally t is a little different from 1/60[sec].
t := n - c.lastUpdated
tt := int(t * int64(fps) / int64(time.Second))
// As t is not accurate 1/60[sec], errors are accumulated.
// To make the FPS stable, set tt 1 if t is a little less than 1/60[sec].
if tt == 0 && (int64(time.Second)/int64(fps)-int64(5*time.Millisecond)) < t {
tt = 1
}
if err := g.UpdateAndDraw(ui.GLContext(), tt); err != nil {
return err
}
c.lastUpdated += int64(tt) * int64(time.Second) / int64(fps)
c.frames++
return nil
}
func (c *graphicsContext) GLContext() *opengl.Context {
if atomic.LoadInt32(&c.initialized) == 0 {
return nil
}
return ui.GLContext()
}