计算凸起畸变过滤器半径的收缩值

Question

我需要根据捏合来增加和减小 GPUImagePinchDistortionFilter 半径，我正在使用捏合手势识别器并存储手势识别器的起始比例。我需要计算 -2.0 和 2.0 之间的收缩比例。这是我的代码。

if([gestureRecognizer state] == UIGestureRecognizerStateBegan) {
    lastScale = [gestureRecognizer scale];
}

if ([gestureRecognizer state] == UIGestureRecognizerStateBegan ||
    [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

    CGFloat currentScale = [[[gestureRecognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];

    CGFloat kMaxScale = 2.0;
    CGFloat kMinScale = -2.0;

    CGFloat newScale = 1.0 - (lastScale - [gestureRecognizer scale]);

    newScale = MIN(newScale, kMaxScale / currentScale);
    newScale = MAX(newScale, kMinScale / currentScale);

    [pinchDistortionFilter setRadius:newScale];
}

我关注了一些帖子来做到这一点。但仍然卡住了，每次用户捏时我都需要设置它，但半径必须在最小和最大范围内。实际上我很困惑如何实现这一点，谁能帮我解决这个问题？

谢谢。

Answer 1

我认为你应该尝试将 lastScale 和半径也保存在正确的位置，并且半径应该 > 0 请参阅下面的答案以了解我的实现，它可能会对你有所帮助。

float currentApplicableScale = (gestureRecognizer.scale/2);

   if (gestureRecognizer.state == UIGestureRecognizerStateEnded) {
       lastRadius = lastScale;
   }else if (gestureRecognizer.state==UIGestureRecognizerStateBegan) {
       firstScale = currentApplicableScale;
   }else if (gestureRecognizer.state == UIGestureRecognizerStateChanged) {
       float radius = currentApplicableScale;

       if (lastRadius<=0) {
           lastRadius = 0.25;
       }

       radius = radius - (firstScale - lastRadius);

       if (radius>0 && radius < 0.5) {

            [(GPUImagePinchDistortionFilter*)pinchFilter setRadius:radius];


           lastScale = radius; //Save here
       }
   }

计算凸起畸变过滤器半径的收缩值

Calculate pinch value for bulge distortion filter radius

ios

uipinchgesturerecognizer

gpuimage