OpenGL着色器问题 [英] OpenGL shaders questions

问题描述

我有一个正在运行的程序，该程序使用glVertexPointer，glNormalPointer等绘制大量元素.这大约可以达到30 FPS.现在，我已经达到了集成着色器将是一个可行选择的地步(每个顶点都需要具有基于特定类计算的颜色). 现在，我的第一个问题是使用着色器会对我的FPS有多大影响?我目前的实施方式(我的99.99％至少存在某种缺陷，将在下面发布代码)将FPS大幅降低至3 FPS.如果FPS的这种下降是正常的，那就没有必要为此奋斗了.

I have a running program that uses glVertexPointer, glNormalPointer etc to draw a large number of elements. This works around 30 FPS. Now I've reach a point where integrating shaders would be a viable option (each vertex need to have a color calculated based on a specific class). 1. Now my first question is how much would using shaders affect my FPS ? My current implementation (which I'm 99.99% is flawed in at least some way, will post code below) drops the FPS drastically to 3 FPS. If this kind of drop in FPS is normal there is no point to struggle with this.

现在输入一些代码.我的着色器看起来像:

Now for some code. My shaders look like:

 vertexsource = """
                  attribute vec3 position; 
                  attribute vec3 normal;
                  varying vec3 norm; 
                  varying vec3 color_out;
                  uniform vec3 color_in;

                  void main() 
                  { 
                      gl_Position = gl_ModelViewProjectionMatrix * vec4( position,1);
                      color_out = color_in; 
                      norm = normal;
                  }""" 
fragmentsource = """ 
                  varying vec3 norm; 
                  varying vec3 color_out;
                  void main() 
                  { 
                      gl_FragColor = vec4( color_out, 1.0);
                  }""" 
vshader = compileShader( vertexsource, GL_VERTEX_SHADER )
fshader = compileShader( fragmentsource, GL_FRAGMENT_SHADER )
program = compileProgram( vshader, fshader ) 
color = glGetUniformLocation( program, "color_in")
normal = glGetAttribLocation( program, "normal" )
position = glGetAttribLocation( program, "position" )
glUseProgram( program )
glUniform3fv( color, 3, (0,0,1) )
return position, normal

所以我返回位置和法线，因为稍后将使用它们传递实际的顶点和法线.从这里我有一个问题.没有着色器，我只使用VertexPointer和NormalPointer传递法线和顶点数组，而OpenGL处理​​其余部分. 2.我读过着色器内置了gl_Vertex和gl_Normal属性.如何将VBO中的值传递给这些着色器?如您所见，当前我正在将顶点位置传递到属性位置，将法线传递给法线，但是我不对法线做任何事情，因为我不知道什么.

So I return position and normal because I will use them later to pass the actual vertices and normals. Right from here I have a question. Without shaders I just pass the normals and vertices arrays using VertexPointer and NormalPointer and OpenGL handles the rest. 2. I've read that shaders have gl_Vertex and gl_Normal attributes build in. How do I pass the values from my VBO's to these ? As you can see currently I'm passing my vertexes position to the attribute position and my normals to normal, but I'm not doing anything with the normals as I don't know what.

绘图是这样完成的:

    glEnableVertexAttribArray( self.position )
    glEnableVertexAttribArray( self.normal )      
    glBindBufferARB(GL_ARRAY_BUFFER_ARB, self.bufferVertices)
    glVertexAttribPointer( self.position, 3, GL_FLOAT, GL_FALSE, 0, None )          
    glEnableClientState(GL_NORMAL_ARRAY);
    glBindBufferARB(GL_ARRAY_BUFFER_ARB, self.bufferNormals)
    glVertexAttribPointer( self.normal, 3, GL_FLOAT, GL_FALSE, 0, None )
    glDrawElements(GL_TRIANGLES, len(self.triangles) , GL_UNSIGNED_SHORT, ADT.voidDataPointer(self.triangles))

在这里self.bufferVertices，self.bufferNormals是VBO包含我的顶点和法线. self.triangles索引数组.到目前为止，它可以绘制正确的索引，但是我的FPS却很低.

Here self.bufferVertices, self.bufferNormals are VBO's containg my vertices and normals. self.triangles indices array. It draws the correct indices so far but my FPS is very low as mentioned.

1. 此绘图顺序是否正确?另外，启用后还可能与着色器发生冲突吗? (GL_LIGHTNING，GL_DEPTH_TEST等)

推荐答案

每次调用该函数(第一个代码)时，您是否都在编译着色器?

Are you compiling your shader each time you call that function (the first code)?

这篇关于OpenGL着色器问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！