question: @ Override public void onNewFrame ( final HeadTransform headTransform ) { FPSCounter . logFrame ( ) ; if ( prefShowEnv && ! bgEnv . isReady ( ) ) { if ( prefShowEnvString . equals ( "Home Theater" ) ) bgEnv . init ( 0 ) ; else bgEnv . init ( 1 ) ; bgEnv . setFixedModel ( ) ; moveThing ( bgEnv ) ; } Matrix . setLookAtM ( mCamera , 0 , 0.0f , 0.0f , CAMERA_Z , 0.0f , 0.0f , 0.0f , 0.0f , 1.0f , 0.0f ) ; GLES20 . glClearColor ( r , g , b , a ) ; headTransform . getHeadView ( mHeadViewSDK , 0 ) ; mHeadViewUse = getHeadView ( ) ; if ( screen . isLookingAtObject ( mHeadViewUse ) ) { aimPoint . setAlpha ( 0 ) ; } else { aimPoint . setAlpha ( 1 ) ; } for ( ButtonThing button : buttonList ) { if ( button . isLookingAtObject ( mHeadViewUse ) && ! button . isHidden ) { if ( fuseStart == - 1 ) { fuseStart = SystemClock . elapsedRealtime ( ) ; fuseButton = button ; } else if ( fuseButton == button ) { checkFuse ( SystemClock . elapsedRealtime ( ) ) ; } } else if ( fuseButton == button ) { checkFuse ( 0 ) ; fuseStart = - 1 ; fuseButton = null ; } } Engine . checkGLError ( "onReadyToDraw" ) ; }
target:  Prepares OpenGL ES before we draw a frame.