c++ - Qt桌面着色器编译问题

Question

我正在使用 Qt 编写一个游戏，我已经实现了一些后期处理着色器以使其看起来更有趣。它工作正常，直到我升级到 linux mint 16，现在我总是收到一个需要精度说明符的错误，这只发生在编译片段着色器时。 因为代码在 android 构建上编译和工作正常，我认为这是因为 QGLShaderProgram 在桌面构建中编译时将 mediump、highp 和 lowp 作为定义添加到着色器的开头。

所以我的问题是:有没有办法让 glsl 编译器不再需要精度说明符，或者我应该研究如何禁止添加这些定义？

代码:

    isOk = m_displaceShader.addShaderFromSourceCode(QGLShader::Vertex,
        "#version 100                                   \n"
        "attribute mediump vec4 in_verts;               \n"
        "varying mediump vec2 out_tex;                  \n"
        "void main(void)                                \n"
        "{                                              \n"
        "   gl_Position = in_verts;                     \n"
        "   out_tex = (in_verts.xy + vec2(1.0)) * 0.5;  \n"
        "}                                              \n");
    qDebug() << m_displaceShader.log();
    isOk &= m_displaceShader.addShaderFromSourceCode(   QGLShader::Fragment,
        "#version 100                                                               \n"
        "uniform sampler2D inCol;                                                   \n"
        "uniform sampler2D inDisplace;                                              \n"
        "varying mediump vec2 out_tex;                                              \n"
        "void main(void)                                                            \n"
        "{                                                                          \n"
        "   mediump vec4 displaceCol = texture2D(inDisplace, out_tex);              \n"
        "   mediump float dispX = (displaceCol.r - 0.5) * 0.2;                      \n"
        "   mediump float dispY = (displaceCol.g - 0.5) * 0.2;                      \n"
        "   mediump vec2 texPlace = out_tex + vec2(dispX, dispY);                   \n"
        "   gl_FragColor = texture2D(inCol, texPlace);                              \n"
#ifdef DEBUG_SHADERS
        "   gl_FragColor = 0.5 * pow(texture2D(inCol, texPlace), vec4(1.0/2.2)) + 0.5 * displaceCol;            \n"
#endif
        "}                                                                          \n"
    );

错误:

QGLShader::compile(Fragment): 0:7(16): error: no precision specified this scope for type `vec2'
0:10(9): error: no precision specified this scope for type `vec4'
0:11(10): error: no precision specified this scope for type `float'
0:12(10): error: no precision specified this scope for type `float'
0:13(9): error: no precision specified this scope for type `vec2'

Answer 1

您正在使用 #version 100，不是有效的桌面 GLSL 版本指令。请参阅 GLSL 4.40 spec 中的以下引述(强调我的):

Any number representing a version of the language a compiler does not support will cause a compile-time error to be generated. Version 1.10 of the language does not require shaders to include this directive, and shaders that do not include a #version directive will be treated as targeting version 1.10. Shaders that specify #version 100 will be treated as targeting version 1.00 of the OpenGL ES Shading Language.

这是为了与 GLES 兼容，而 GLES SL 需要这些精度说明符，因此您的编译器是正确的。