（译）如何使用cocos2d2.0来给一个Sprite添加遮罩

git clone https://github.com/cocos2d/cocos2d-iphone.git

cd cocos2d-iphone
git checkout gles20

./install-templates.sh -f -u

// Add to top of file
#import "SimpleAudioEngine.h"
 
// At end of applicationDidFinishLaunching, replace last line with the following 2 lines:
[[SimpleAudioEngine sharedEngine] playBackgroundMusic:@"TeaRoots.mp3" loop:YES];
[[CCDirector sharedDirector] runWithScene: [HelloWorldLayer sceneWithLastCalendar:0]];

return ( UIInterfaceOrientationIsLandscape( interfaceOrientation ) );

// Add new instance variable
int calendarNum;
 
// Replace the +(CCScene*) scene declaration at the bottom with the following:
+ (CCScene *) sceneWithLastCalendar:(int)lastCalendar;
- (id)initWithLastCalendar:(int)lastCalendar;

// Replace +(CCScene *) scene with the following
+(CCScene *) sceneWithLastCalendar:(int)lastCalendar // new
{
    CCScene *scene = [CCScene node];
    HelloWorldLayer *layer = [[[HelloWorldLayer alloc] 
        initWithLastCalendar:lastCalendar] autorelease]; // new
    [scene addChild: layer];    
    return scene;
}
 
// Replace init with the following
-(id) initWithLastCalendar:(int)lastCalendar
{
    if( (self=[super init])) {
 
        CGSize winSize = [CCDirector sharedDirector].winSize;
 
        do {
            calendarNum = arc4random() %3+1;
        } while (calendarNum == lastCalendar);
 
        NSString * spriteName = [NSString 
            stringWithFormat:@"Calendar%d.png", calendarNum];
 
        // BEGINTEMP
        CCSprite * cal = [CCSprite spriteWithFile:spriteName];        
        cal.position = ccp(winSize.width/2, winSize.height/2);        
        [self addChild:cal];
        // ENDTEMP
 
        self.isTouchEnabled = YES;
    }
    return self;
}
 
// Add new methods
- (void)registerWithTouchDispatcher {
    [[CCTouchDispatcher sharedDispatcher] addTargetedDelegate:self 
        priority:0 swallowsTouches:YES];
}
 
- (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event {
    CCScene *scene = [HelloWorldLayer sceneWithLastCalendar:calendarNum];
    [[CCDirector sharedDirector] replaceScene:
        [CCTransitionJumpZoom transitionWithDuration:1.0 scene:scene]];
    return TRUE;
}

attribute vec4 a_position;

attribute vec2 a_texCoord;

attributevec4 a_color;

uniformmat4 u_MVPMatrix;

varying vec4 v_fragmentColor;

varying vec2 v_texCoord;

void main()

{

    gl_Position = u_MVPMatrix * a_position;

    v_fragmentColor = a_color;

    v_texCoord = a_texCoord;

}

#ifdef GL_ES
precision lowp float;
#endif
 
varying vec4 v_fragmentColor;
varying vec2 v_texCoord;
uniform sampler2D u_texture;
 
void main()
{
    gl_FragColor = v_fragmentColor * texture2D(u_texture, v_texCoord);
}

#ifdef GL_ES
precision lowp float;
#endif
 
varying vec4 v_fragmentColor;
varying vec2 v_texCoord;
uniform sampler2D u_texture;
uniform sampler2D u_mask;
 
void main()
{
    vec4 texColor = texture2D(u_texture, v_texCoord);
    vec4 maskColor = texture2D(u_mask, v_texCoord);
    vec4 finalColor = vec4(texColor.r, texColor.g, texColor.b, maskColor.a * texColor.a);
    gl_FragColor = v_fragmentColor * finalColor;
}

#import "cocos2d.h"
 
@interface MaskedSprite : CCSprite {
    CCTexture2D * _maskTexture;
    GLuint _textureLocation;
    GLuint _maskLocation;
}
 
@end

#import "MaskedSprite.h"



@implementation MaskedSprite

- (id)initWithFile:(NSString *)file 
{
    self = [super initWithFile:file];
    if (self) {
        
        // 1
        _maskTexture = [[[CCTextureCache sharedTextureCache] addImage:@"CalendarMask.png"] retain];
        
        // 2
        self.shaderProgram = 
        [[[GLProgram alloc] 
          initWithVertexShaderFilename:@"PositionTextureColor.vsh"
          fragmentShaderFilename:@"Mask.fsh"] autorelease];
        
        CHECK_GL_ERROR_DEBUG();
        
        // 3
        [shaderProgram_ addAttribute:kCCAttributeNamePosition index:kCCVertexAttrib_Position];
        [shaderProgram_ addAttribute:kCCAttributeNameColor index:kCCVertexAttrib_Color];
        [shaderProgram_ addAttribute:kCCAttributeNameTexCoord index:kCCVertexAttrib_TexCoords];
        
        CHECK_GL_ERROR_DEBUG();
        
        // 4
        [shaderProgram_ link];
        
        CHECK_GL_ERROR_DEBUG();
        
        // 5
        [shaderProgram_ updateUniforms];
        
        CHECK_GL_ERROR_DEBUG();                
        
        // 6
        _textureLocation = glGetUniformLocation( shaderProgram_->program_, "u_texture");
        _maskLocation = glGetUniformLocation( shaderProgram_->program_, "u_mask");
        
        CHECK_GL_ERROR_DEBUG();
        
    }
    
    return self;
}
@end

-(void) draw {    
    
    // 1 
    ccGLBlendFunc( blendFunc_.src, blendFunc_.dst );        
    ccGLUseProgram( shaderProgram_->program_ );
    
//    ccGLUniformProjectionMatrix( shaderProgram_ );
//    ccGLUniformModelViewMatrix( shaderProgram_ );
    ccGLUniformModelViewProjectionMatrix(shaderProgram_);
    
    // 2
    glActiveTexture(GL_TEXTURE0);
    glBindTexture( GL_TEXTURE_2D,  [texture_ name] );
    glUniform1i(_textureLocation, 0);
    
    glActiveTexture(GL_TEXTURE1);
    glBindTexture( GL_TEXTURE_2D,  [_maskTexture name] );
    glUniform1i(_maskLocation, 1);
    
    // 3
#define kQuadSize sizeof(quad_.bl)
    long offset = (long)&quad_;
    
    // vertex
    NSInteger diff = offsetof( ccV3F_C4B_T2F, vertices);
    glVertexAttribPointer(kCCVertexAttrib_Position, 3, GL_FLOAT, GL_FALSE, kQuadSize, (void*) (offset + diff));
    
    // texCoods
    diff = offsetof( ccV3F_C4B_T2F, texCoords);
    glVertexAttribPointer(kCCVertexAttrib_TexCoords, 2, GL_FLOAT, GL_FALSE, kQuadSize, (void*)(offset + diff));
    
    // color
    diff = offsetof( ccV3F_C4B_T2F, colors);
    glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_UNSIGNED_BYTE, GL_TRUE, kQuadSize, (void*)(offset + diff));
    
    // 4
    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);    
    glActiveTexture(GL_TEXTURE0);
}

// Add to top of file
#import "MaskedSprite.h"
 
// Replace code between BEGINTEMP and ENDTEMP with the following
MaskedSprite * maskedCal = [MaskedSprite spriteWithFile:spriteName];
maskedCal.position = ccp(winSize.width/2, winSize.height/2);
[self addChild:maskedCal];