将核心动画与OpenGL ES结合在一起 [英] Marrying Core Animation with OpenGL ES

问题描述

编辑：我想而不是下面的长解释我也可能会问：将 -setNeedsDisplay 发送到 CAEAGLLayer 不会导致图层重绘（即，不会调用 -drawInContext：）。相反，我得到这个控制台消息：

I suppose instead of the long explanation below I might also ask: Sending -setNeedsDisplay to an instance of CAEAGLLayer does not cause the layer to redraw (i.e., -drawInContext: is not called). Instead, I get this console message:

<GLLayer: 0x4d500b0>: calling -display has no effect.

有没有解决这个问题的方法？当调用 -setNeedsDisplay 时，我可以调用 -drawInContext：吗？下面详细说明：

Is there a way around this issue? Can I invoke -drawInContext: when -setNeedsDisplay is called? Long explanation below:

我有一个OpenGL场景，我想使用Core Animation动画制作动画。

I have an OpenGL scene that I would like to animate using Core Animation animations.

遵循在CALayer中设置自定义属性动画的标准方法，我创建了一个 CAEAGLLayer 的子类，并定义了一个属性 sceneCenterPoint ，其值应该是动画的。我的图层还包含对OpenGL渲染器的引用：

Following the standard approach to animate custom properties in a CALayer, I created a subclass of CAEAGLLayer and defined a property sceneCenterPoint in it whose value should be animated. My layer also holds a reference to the OpenGL renderer:

#import <UIKit/UIKit.h>
#import <QuartzCore/QuartzCore.h>
#import "ES2Renderer.h"

@interface GLLayer : CAEAGLLayer
{
    ES2Renderer *renderer;
}

@property (nonatomic, retain) ES2Renderer *renderer;
@property (nonatomic, assign) CGPoint sceneCenterPoint;

然后我将属性 @dynamic 声明为让CA创建访问器，覆盖 + needsDisplayForKey：并实现 -drawInContext：以传递<$的当前值c $ c> sceneCenterPoint 渲染器的属性并要求它渲染场景：

I then declare the property @dynamic to let CA create the accessors, override +needsDisplayForKey: and implement -drawInContext: to pass the current value of the sceneCenterPoint property to the renderer and ask it to render the scene:

#import "GLLayer.h"

@implementation GLLayer

@synthesize renderer;
@dynamic sceneCenterPoint;

+ (BOOL) needsDisplayForKey:(NSString *)key
{
    if ([key isEqualToString:@"sceneCenterPoint"]) {
        return YES;
    } else {
        return [super needsDisplayForKey:key];
    }
}

- (void) drawInContext:(CGContextRef)ctx
{
    self.renderer.centerPoint = self.sceneCenterPoint;
    [self.renderer render];
}
...

（如果您有权访问WWDC 2009会话视频，您可以在会话303（动画绘图）中查看此技术。

(If you have access to the WWDC 2009 session videos, you can review this technique in session 303 ("Animated Drawing")).

现在，当我在keyPath <$上为图层创建显式动画时c $ c> @sceneCenterPoint，Core Animation应计算自定义属性的插值，并为每个步骤调用 -drawInContext：动画：

Now, when I create an explicit animation for the layer on the keyPath @"sceneCenterPoint", Core Animation should calculate the interpolated values for the custom properties and call -drawInContext: for each step of the animation:

- (IBAction)animateButtonTapped:(id)sender
{
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"sceneCenterPoint"];
    animation.duration = 1.0;
    animation.fromValue = [NSValue valueWithCGPoint:CGPointZero];
    animation.toValue = [NSValue valueWithCGPoint:CGPointMake(1.0f, 1.0f)];
    [self.glView.layer addAnimation:animation forKey:nil];
}

至少这是正常的会发生什么CALayer 子类。当我继承 CAEAGLLayer 时，我会在控制台上为动画的每一步获得此输出：

At least that is what would happen for a normal CALayer subclass. When I subclass CAEAGLLayer, I get this output on the console for each step of the animation:

2010-12-21 13:59:22.180 CoreAnimationOpenGL[7496:207] <GLLayer: 0x4e0be20>: calling -display has no effect.
2010-12-21 13:59:22.198 CoreAnimationOpenGL[7496:207] <GLLayer: 0x4e0be20>: calling -display has no effect.
2010-12-21 13:59:22.216 CoreAnimationOpenGL[7496:207] <GLLayer: 0x4e0be20>: calling -display has no effect.
2010-12-21 13:59:22.233 CoreAnimationOpenGL[7496:207] <GLLayer: 0x4e0be20>: calling -display has no effect.
...

所以看来，可能出于性能原因，对于OpenGL图层， -drawInContext：未被调用，因为这些图层不使用标准 -display 绘制自己的方法。任何人都可以证实吗？有办法吗？

So it seems that, possibly for performance reasons, for OpenGL layers, -drawInContext: is not getting called because these layers do not use the standard -display method to draw themselves. Can anybody confirm that? Is there a way around it?

或者我可以不使用上面列出的技术吗？这意味着我必须在OpenGL渲染器中手动实现动画（这可能但不是优雅的IMO）。

Or can I not use the technique I laid out above? This would mean I would have to implement the animations manually in the OpenGL renderer (which is possible but not as elegant IMO).

推荐答案

您是否尝试在OpenGL图层上方创建父图层并为其设置动画？

Have you tried making a parent layer above the OpenGL layer and animating that instead?

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