在 cocos2d 中使用 opengl-es 进行圆形裁剪 [英] Circle shape clipping with opengl-es in cocos2d

问题描述

我正在尝试在 cocos2d 中的 CCSprite 上制作圆形剪裁，经过大量搜索后，我尝试了 open gl glScissor 方法，我在我的 sprite 上实现了平方剪裁.但是，我需要把它做成一个圆圈，而且用 glScissor 似乎是不可能的.我一直在尝试，我发现了一些关于 gl 模板的东西，但是我还没有找到关于这个的方法，而且我不熟悉 opengl.

I'm trying to make a circle shape clipping on a CCSprite in cocos2d, after searching a lot, i tried the open gl glScissor method, i achieve an squared clipping over my sprite. But, i need to make it a circle, and it seems to be impossible to do with the glScissor. I kept trying and I found something about gl stencil, but I haven't found a how to on this and I'm not familiar with opengl.

我还听说过多次调用 glScissor wo 可以实现自定义形状，但我没有找到任何东西.

Also I heard something about calling multiple times to the glScissor wo you can achieve a custom shape but i haven't found anything.

提前致谢，欢迎任何回答.

Thanks in advance, any answer is welcome.

这是我实际的访问方式:

this is my actual visit method:

-(void) visit
{
    glPushMatrix();
    glEnable(GL_SCISSOR_TEST);

    glScissor(clippingRegion.origin.x , clippingRegion.origin.y ,
            clippingRegion.size.width, clippingRegion.size.height);

    [super visit];

    glDisable(GL_SCISSOR_TEST);
    glPopMatrix();

}

推荐答案

glScissor 不会做你想做的事.这是我不久前写的一些代码的一部分.它画一个带有光栅纹理的矩形，并使用模板缓冲区只有一个磁盘可见.

glScissor won't do what you want. Here is part of some code I wrote a while ago. It draws a rectangle with a grating texture and uses the stencil buffer to only have a disk visible.

这是我当时使用的链接:http://www.swiftless.com/tutorials/opengl/basic_reflection.html

Here is the link I used back then: http://www.swiftless.com/tutorials/opengl/basic_reflection.html

(let ((cnt 0d0))
  (defmethod display ((w window))
    ;; the complex number z represents amplitude and direction
    ;; of the grating constant
    ;; r and psi addresses different points in the back focal plane
    ;; r=0 will result in z=w0. the system is aligned to illuminate
    ;; the center of the back focal plane for z=w0.
    (let* ((w0 (* 540d0 (exp (complex 0d0 (/ pi 4d0)))))
           (r 260d0)
           (psi 270d0)
           (w (* r (exp (complex 0d0 (* psi (/ pi 180d0))))))
           (z (+ w w0)))
      (clear-stencil 0)
      (clear :color-buffer-bit :stencil-buffer-bit)
      (load-identity)
      ;; http://www.swiftless.com/tutorials/
      ;;    opengl/basic_reflection.html
      ;; use stencil buffer to cut a disk out of the grating
      (color-mask :false :false :false :false)
      (depth-mask :false)
      (enable :stencil-test)
      (stencil-func :always 1 #xffffff)
      (stencil-op :replace :replace :replace)

      (draw-disk 100d0 (* .5d0 1920) (*  .5d0 1080))
      ;; center on camera 549,365
      ;; 400 pixels on lcos = 276 pixels on camera (with binning 2)
      (color-mask :true :true :true :true)
      (depth-mask :false)
      (stencil-func :equal 1 #xffffff)
      (stencil-op :keep :keep :keep)

      ;; draw the grating
      (disable :depth-test)
      (with-pushed-matrix 
          (translate (* .5 1920) (*  .5 1080) 0)
        (rotate (* (phase z) 180d0 (/ pi)) 0 0 1)
        (translate (* -.5 1920) (* -.5 1080) 0)
        (draw *bild*))
      (disable :stencil-test)
      (enable :depth-test)

      (fill-grating *grating* (abs z))
      (format t "~a~%" cnt)
      (if (< cnt 360d0)
          (incf cnt 30d0)
          (setf cnt 0d0))
      (update *bild*)
      (swap-buffers)
      (sleep (/ 1d0)) ;; 1 frame per second
      (post-redisplay))))

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