objective-c – 试图通过UIRotationGestureController模拟动量/

基本上我所做的是设置一个定期调用某些方法的NSTimer.我只是采取方向和速度来创建一个旋转矩阵(正如我所说,3D有点肮脏：P),我将速度乘以一些小于1的数字,因此它会下降.乘以而不是减去的原因是,如果来自用户的旋转是硬的两倍,则不希望对象旋转两倍,因为等待我发现变得烦人.

至于确定车轮旋转的方向,只需将其存储在touchesEnded：withEvent：方法中,其中包含所有信息.既然你说你已经有了跟踪功能,只要用户手指向下,这应该是显而易见的.

我在3D中拥有的是：

// MyView.h
@interface MyView : UIView {
    NSTimer *animationTimer;
}
- (void) startAnimation;
@end


// MyAppDelegate.h
@implementation MyAppDelegate

- (void) applicationDidFinishLaunching:(UIApplication *)application {
    [myView startAnimation];
}

@end

// MyView.m
GLfloat rotationMomentum = 0;
GLfloat rotationDeltaX  = 0.0f;
GLfloat rotationDeltaY  = 0.0f;

@implementation MyView
- (void)startAnimation {
    animationTimer = [NSTimer scheduledTimerWithTimeInterval:(NSTimeInterval)((1.0 / 60.0) * animationFrameInterval) target:self selector:@selector(drawView:) userInfo:nil repeats:TRUE];
}

- (void) drawView:(id)sender {
    addRotationByDegree(rotationMomentum);
    rotationMomentum /= 1.05;
    if (rotationMomentum < 0.1)
        rotationMomentum = 0.1; // never stop rotating completely
    [renderer render];
}

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
}

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    UITouch *aTouch = [touches anyObject];
    CGPoint loc = [aTouch locationInView:self];
    CGPoint prevloc = [aTouch previousLocationInView:self];

    rotationDeltaX = loc.x - prevloc.x;
    rotationDeltaY = loc.y - prevloc.y;

    GLfloat distance = sqrt(rotationDeltaX*rotationDeltaX+rotationDeltaY*rotationDeltaY)/4;
    rotationMomentum = distance;
    addRotationByDegree(distance);

    self->moved = TRUE;
}

- (void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
{
}

- (void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event
{
}

我省略了addRotationByDegree函数,但它做的是它使用全局变量rotationDeltaX和rotationDeltaY并将旋转矩阵应用于已存储的矩阵,然后保存结果.在你的例子中,你可能想要更简单的东西,比如(我现在假设只有X方向的运动才能转动轮子)：

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    UITouch *aTouch = [touches anyObject];
    CGPoint loc = [aTouch locationInView:self];
    CGPoint prevloc = [aTouch previousLocationInView:self];

    GLfloat distance = loc.x - prevloc.x;
    rotationMomentum = distance;
    addRotationByDegree(distance);

    self->moved = TRUE;
}

void addRotationByDegree(distance) {
    angleOfWheel += distance; // probably need to divide the number with something reasonable here to have the spin be nicer
}