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我试图在这里实现类似聚光灯演示：http: //www.supersuraccoon-cocos2d.com/2011/09/09/spot-light-demo/

我设法在渲染纹理中添加了几个聚光灯，但我仍然有一个问题，如何在不清除整个纹理的情​​况下只移除一个聚光灯？

这是 CCSpotLight.m 中的绘图代码：

-(void) drawSpotLight 
{   
int segs = 15;
GLfloat *vertices = malloc( sizeof(GLfloat)*2*(segs));
GLfloat *coordinates = malloc( sizeof(GLfloat)*2*(segs));
ccColor4B *colors = malloc( sizeof(ccColor4B)*(segs));

memset(vertices,0, sizeof(GLfloat)*2*(segs));//Set first (3rd param) of the block of memory pointed by vertices to 0

memset(coordinates,0, sizeof(GLfloat)*2*(segs));

colors[0] = ccc4(0, 0, 0, 255);//opaque
for (int i = 1; i < segs; i++)
{
    colors[i] = ccc4(0, 0, 0, 0);//transparent
}

const float coef = 2.0f * (float)M_PI/(segs-2) ;

vertices[0] = self.position.x;
vertices[1] = self.position.y;
coordinates[0] = self.position.x;
coordinates[1] = (contentSize_.height-self.position.y);
for(int i=1;i<=segs;i++)
{
    float rads = i*coef;
    float j = self.spotLightRadius * cosf(rads) + self.position.x;
    float k = self.spotLightRadius * sinf(rads) + self.position.y;

    vertices[i*2] = j;
    vertices[i*2+1] = k;

    coordinates[i*2] = (j);
    coordinates[i*2+1] = (contentSize_.height-k);
}

// Update the render texture
[self.renderTexture begin];

glBindTexture(GL_TEXTURE_2D, (GLuint)self.renderTexture);//bind a named texture to a texturing target (2d texture)
glBlendFunc(GL_ZERO, GL_ONE_MINUS_SRC_ALPHA);

glColorMask(0.0f, 0.0f, 0.0f, 1.0f);//enable and disable writing of frame buffer color components

glVertexPointer(2, GL_FLOAT, 0, vertices);//define an array of vertex data
glTexCoordPointer(2, GL_FLOAT, 0, coordinates);
glColorPointer(4, GL_UNSIGNED_BYTE, 0, colors);

glDrawArrays(GL_TRIANGLE_FAN, 0, segs);

glColorMask(1.0f, 1.0f, 1.0f, 1.0f);
glBlendFunc(CC_BLEND_SRC, CC_BLEND_DST);

[self.renderTexture end];

free(vertices);
free(coordinates);
free(colors);
}

以及 HelloWorldLayer.m 中的实例化代码：

renderLayer = [CCRenderTexture renderTextureWithWidth:480
                                                                    height:320];
    renderLayer.position = ccp(240, 160);
    [renderLayer clear:0 
                     g:0
                     b:0
                     a:0.5];
    [[renderLayer sprite] setBlendFunc: (ccBlendFunc) { GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA }];

    [self addChild:renderLayer z:0];

CCSpotLight *spotLight1 = [CCSpotLight initWithRenderTexture:renderLayer
                                                spotLightRadius:60.0f
                                                    renderColor:ccc4(0, 0, 0, 255)
                                                              x:224
                                                              y:160];
    [self addChild:spotLight1 z:1];

//adding another spotlight which should be removed when the user touches the screen
CCSpotLight *spotLight2 = [CCSpotLight initWithRenderTexture:renderLayer
                                                spotLightRadius:60.0f
                                                    renderColor:ccc4(0, 0, 0, 255)
                                                              x:124
                                                              y:160];
    [self addChild:spotLight2 z:1];//for removing it, I tried [spotLight2 removeFromParentAndCleanup:YES] but it didn't work, no change at all
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