我试图从这里运行SSDO演示代码，但是遇到了几个问题，在我花了几个小时寻找解决方案之后，这些问题使我更加困惑。 尽管如此，现在我几乎可以肯定问题出在GLSL版本上。

注意:

• 演示使用glew和glut。
• 我的环境是Windows 10 pro上的Microsoft Visual Studio Community 2019，15“MacBook pro 2018上的Parallels Desktop支持。

在对代码进行任何修改之前，我得到了一堆错误消息:

ERROR: 0:15: Invalid call of undeclared identifier 'texelFetch2D'
ERROR: 0:16: Invalid call of undeclared identifier 'texelFetch2D'
ERROR: 0:17: Invalid call of undeclared identifier 'texelFetch2D'
ERROR: 0:19: Use of undeclared identifier 'pixelPosition'
ERROR: 0:20: Use of undeclared identifier 'lightVector'
ERROR: 0:21: Use of undeclared identifier 'lightVector'
ERROR: 0:21: Use of undeclared identifier 'lightDistance'
ERROR: 0:23: Use of undeclared identifier 'pixelNormal'
ERROR: 0:24: Use of undeclared identifier 'pixelNormal'
ERROR: 0:24: Use of undeclared identifier 'pixelNormal'
ERROR: 0:25: Use of undeclared identifier 'lightDir'
ERROR: 0:25: Use of undeclared identifier 'pixelNormal'
ERROR: 0:27: Use of undeclared identifier 'cosAlpha'
ERROR: 0:27: Use of undeclared identifier 'pixelReflectance'
ERROR: 0:32: Use of undeclared identifier 'diffuseColor'

ERROR: One or more attached shaders not successfully compiled
...

其他着色器也会出现类似的消息。
相应地，上面显示的错误消息与create_direct_light_buffere.frag:

varying vec4 position;
varying vec3 normal;

uniform vec4 lightPosition;
uniform vec4 lightColor;

uniform sampler2D positionTexture;
uniform sampler2D normalTexture;
uniform sampler2D reflectanceTexture;


void main()
{   
    vec4 pixelPosition = texelFetch2D(positionTexture, ivec2(gl_FragCoord.xy), 0);
    vec4 pixelNormal = texelFetch2D(normalTexture, ivec2(gl_FragCoord.xy), 0);
    vec4 pixelReflectance = texelFetch2D(reflectanceTexture, ivec2(gl_FragCoord.xy), 0);
    
    vec3 lightVector = lightPosition.xyz - pixelPosition.xyz;       // vector to light source
    float lightDistance = length(lightVector);         // distance to light source
    vec3 lightDir = lightVector / lightDistance;       // normalized vector to light source

    pixelNormal.w = 0.0;
    pixelNormal = normalize(pixelNormal);
    float cosAlpha = max(0.0, dot(lightDir.xyz, pixelNormal.xyz));
    
    vec4 diffuseColor = vec4(cosAlpha) * pixelReflectance;
    // vec4 ambientColor = vec4(0.2, 0.2, 0.2, 1.0);
    
    // diffuseColor += ambientColor;

    gl_FragColor = diffuseColor;
    gl_FragColor.a = 1.0;
}

显然，我搜索了texelfetch2d，但只获得了非常有限的信息。 然而，根据这些信息，我试探性地假设用texelfetch替换它会有所帮助，根据本页，这需要一个不低于1.30的GLSL版本。

所以我在create_direct_light_buffere.frag的开头添加了#version130，错误消息变成了:

ERROR: 0:1: '' :  version '130' is not supported

ERROR: One or more attached shaders not successfully compiled
...

然后我采纳了@Flyx的建议，在main函数中添加指定版本:

glutInitContextVersion(3, 2);
glutInitContextProfile(GLUT_CORE_PROFILE);

我开始迷路了。

错误消息变为:

WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord5' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord6' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord0' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_SecondaryColor' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord4' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord7' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_FogCoord' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord1' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord3' to match BindAttributeLocation request.
WARNING: Could not find vertex shader attribute 'PRLGLSL_MultiTexCoord2' to match BindAttributeLocation request.

C
ERROR: 0:2: 'varying' : syntax error: syntax error

ERROR: One or more attached shaders not successfully compiled
...

这些警告似乎与create_direct_light_buffere.frag无关，而且我找不到任何有关它们的问题和解决方案，所以我就让它们过去了。
当我试图找出variable错误时，我发现了这篇文章，它声称自GLSL版本1.30以来，variable被in或out替换。

这就是标题中的冲突。

1. 演示完全正确吗？
2. 如果可以运行该项目，应该怎么做？

由于我是OpenGL的新手，如果有人能下载源代码在自己的电脑上试用并告诉我如何解决它，我将不胜感激。
如果一些经验丰富的专家能给我一些关于可能出现的错误或如何解决这个问题的一般性建议，我将同样感激。