cocos2d-iphone - Cocos2d 中的旋转剪切节点

Question

我在这里使用裁剪节点:http://www.learn-cocos2d.com/2011/01/cocos2d-gem-clippingnode

剪辑节点.h

#import "cocos2d.h"
@interface ClippingNode : CCNode {
    CGRect clippingRegionInNodeCoordinates;
    CGRect clippingRegion;
}
@property (nonatomic) CGRect clippingRegion;
@end

剪裁节点.m

#import "ClippingNode.h"

@interface ClippingNode (PrivateMethods)
-(void) deviceOrientationChanged:(NSNotification*)notification;
@end

@implementation ClippingNode
-(CGRect) clippingRegion {
    return clippingRegionInNodeCoordinates;
}

-(void) setClippingRegion:(CGRect)region {

    // keep the original region coordinates in case the user wants them back unchanged
    clippingRegionInNodeCoordinates = region;
    self.position = clippingRegionInNodeCoordinates.origin;
    self.contentSize = clippingRegionInNodeCoordinates.size;

    // convert to retina coordinates if needed
    region = CC_RECT_POINTS_TO_PIXELS(region);

    // respect scaling
    clippingRegion = CGRectMake(region.origin.x * scaleX_, region.origin.y * scaleY_,
                            region.size.width * scaleX_, region.size.height * scaleY_);
}

-(void) setScale:(float)newScale {
    [super setScale:newScale];
    // re-adjust the clipping region according to the current scale factor
    [self setClippingRegion:clippingRegionInNodeCoordinates];
}

-(void) deviceOrientationChanged:(NSNotification*)notification {
    // re-adjust the clipping region according to the current orientation
    [self setClippingRegion:clippingRegionInNodeCoordinates];
}

-(void) visit {

    glEnable(GL_SCISSOR_TEST);
    CGPoint worldPosition = [self convertToWorldSpace:CGPointZero];
    const CGFloat s = [[CCDirector sharedDirector] contentScaleFactor];
    glScissor((clippingRegion.origin.x) + (worldPosition.x*s), (clippingRegion.origin.y) + (worldPosition.y*s),
          (clippingRegion.size.width), (clippingRegion.size.height));

    [super visit];

    glDisable(GL_SCISSOR_TEST);

}
@end

但是，我需要剪辑一个旋转的 CCNode。关于我如何完成这样的任务的任何想法？

Answer 1

用这个替换类 ClippingNode 中的访问方法

-(void) visit
{

    float rotationAngle = 15;

    glPushMatrix();

    CCRenderTexture* renderTexture = [[CCRenderTexture renderTextureWithWidth:512 height:512] retain];

    glEnable(GL_SCISSOR_TEST);
    glScissor(0, 0, clippingRegion.size.width, clippingRegion.size.height);

    [renderTexture begin];

    glPushMatrix();
    glRotatef(rotationAngle, 0, 0, 1);
    glTranslatef(-clippingRegion.origin.x, -clippingRegion.origin.y, 0);

    [super visit];

    glPopMatrix();

    [renderTexture end];

    glDisable(GL_SCISSOR_TEST);

    renderTexture.sprite.position = CGPointMake(clippingRegion.origin.x , clippingRegion.origin.y);
    renderTexture.sprite.anchorPoint = CGPointMake(0, 1);
    renderTexture.sprite.rotation = rotationAngle;
    [renderTexture.sprite visit];

    [renderTexture release];

    glPopMatrix();
}

基本上它会创建一个纹理来渲染 ClippingNode 内容

然后平移场景，使剪切区域的原点现在位于 (0,0)

通过rotationAngle旋转整个场景

启用剪刀

渲染场景

平移、旋转和渲染包含纹理的 Sprite