Z-fighting解决方案在OpenGL中进行深度测试 - 它们是如何工作的？ [英] Z-fighting solutions in depth test in OpenGL - how do they work?

问题描述

描述

我在OpenGL中遇到了Z-Fighting的主要问题，并且我花了相当多的时间为此寻找解决方案问题。一些我发现并理解并不喜欢的：

• 将多边形彼此移开（如OpenGL中的glPolygonOffset ）


• 根据Z坐标分割场景，并使用单独的干净z缓冲区绘制场景的一部分。 $ b

  那些我不明白的：
  
  

  
  
  • 使用投影矩阵
    https://software.intel.com/en-us/articles/使用对数深度缓冲区
    $ a
  ：//outerra.blogspot.com/2012/11/maximizing-depth-buffer-range-and.html> http://outerra.blogspot.com/2012/11/maximizing-depth-buffer-range-and。 HTML
  
  
  
  

  我在程序中实现了第二个，只是把它放到了一个球的顶点着色器中它与地面战斗）：

  b
  $ b

    float C = 1.0; 
   float far = 2000.0; 
   gl_Position = u_projView * a_position; 
   gl_Position.z = 2.0 * log（gl_Position.w * C + 1.0）/ log（far * C + 1.0） -  1.0; 
   gl_Position.z * = gl_Position.w; 
    

  并且工作正常！
  
  

  实际问题

  
  
  
  
  
  1. 任何人都可以解释我怎么改变顶点着色器中顶点的Z坐标解决了这个问题将顶点明显移动到我身上？ （场景看起来与人眼相同）。它是如何改变z深度值的分布的？我猜测我错过了关于渲染管道的一些知识。
  
  
  2. 任何人都可以向我解释我们如何使用投影矩阵来解决问题？它是如何工作的？
  
  
  3. 是否还有其他类似的有效方法来解决z战斗问题？
  
  

  谢谢！
  

  解决方案

  也许深度缓冲精度有问题吗？当使用16位缓冲区时，z战斗可能发生。您可以使用以下方式进行检查：

    glGetIntegerv（GL_DEPTH_BITS，& depthBits）; 
    

  
  

  Description

  I've had major problems with Z-Fighting in OpenGL and I've spent quite some time finding solutions for this problem. Some of the ones I've found and I understand and didn't like:

  • Moving polygons away from each other ( like glPolygonOffset in OpenGL )
  • Dividing the scene according to Z coordinate and drawing parts of the scene with separate clean z-buffers.

  The ones I don't understand:

  • Using Projection Matrix https://software.intel.com/en-us/articles/alternatives-to-using-z-bias-to-fix-z-fighting-issues
  • Using "Logarithmic Depth Buffers" http://outerra.blogspot.com/2012/11/maximizing-depth-buffer-range-and.html

  I've implemented the second one in my program by just puting this into the vertex shader of a ball (it z-fought with the ground) :

  float C = 1.0; 
  float far = 2000.0; 
     gl_Position = u_projView * a_position;      
  gl_Position.z = 2.0*log(gl_Position.w*C + 1.0)/log(far*C + 1.0) - 1.0;
  gl_Position.z *= gl_Position.w;
  

  and it worked!

  Actual Questions

  1. Can anyone explain me how did changing the Z coordinate of the vertex in the vertex shader solved the problem WITHOUT moving the vertex visibly to me ? (the scene looks the same to the human eye). How did it change the distribution of the z-depth values ? I'm guessing i'm missing some knowledge about rendering pipeline.
  2. Can anyone explain to me how can we use Projection Matrix to fix the problem ? And how does it work?
  3. Are there any other similarly effective ways to fixing z-fighting problem?

  Thanks!

  解决方案

  Maybe there's a problem with depth buffer precision? When using 16-bit buffer, z-fighting is likely to happen. You can check it using:

  glGetIntegerv( GL_DEPTH_BITS, &depthBits);
  

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