Using certain OpenGL functions on Linux...

[tmason101]

Hello,

The following code block below works on Windows (in VC++ 2013) because I have included GL/glew.h but using QT Creator on Linux it undefines the include so the functions in bold below are not available.

What can I do to be able to use the OpenGL functions glGetUniformBlockIndex(), glUniformBlockBinding(), and glBindBufferBase() under Linux like how I use these functions under Windows?

Thank you for your time.
@
void QTOpenGLWindow::loadShaderUniforms() {

glUseProgram(MainOpenGLShaderProgramID);

MatricesUniformBlockID = glGetUniformBlockIndex(MainOpenGLShaderProgramID, "Matrices");
glUniformBlockBinding(MainOpenGLShaderProgramID, MatricesUniformBlockID, 1);
glGenBuffers(1, &MatricesUniformBufferID);
glBindBuffer(GL_UNIFORM_BUFFER, MatricesUniformBufferID);
glBindBufferBase(GL_UNIFORM_BUFFER, 1, MatricesUniformBufferID);
GLsizeiptr TotalBufferSize = sizeof(glm::mat4) + sizeof(glm::mat4);
TotalBufferSize += sizeof(glm::mat3);

glBufferData(GL_UNIFORM_BUFFER, TotalBufferSize, NULL, GL_DYNAMIC_DRAW);
glBindBuffer(GL_UNIFORM_BUFFER, NULL);

LightsUniformBlockID = glGetUniformBlockIndex(MainOpenGLShaderProgramID, "Lights");
glUniformBlockBinding(MainOpenGLShaderProgramID, LightsUniformBlockID, 2);
glGenBuffers(1, &LightsUniformBufferID);
glBindBuffer(GL_UNIFORM_BUFFER, LightsUniformBufferID);
glBindBufferBase(GL_UNIFORM_BUFFER, 2, LightsUniformBufferID);

GLfloat LightDirection[3] = { -4.0f, -3.0f, -3.0f };

glBufferData(GL_UNIFORM_BUFFER, sizeof(LightDirection), &LightDirection, GL_DYNAMIC_DRAW);
glBindBuffer(GL_UNIFORM_BUFFER, NULL);

MaterialsUniformBlockID = glGetUniformBlockIndex(MainOpenGLShaderProgramID, "Materials");
glUniformBlockBinding(MainOpenGLShaderProgramID, MaterialsUniformBlockID, 3);
glGenBuffers(1, &MaterialsUniformBufferID);
glBindBuffer(GL_UNIFORM_BUFFER, MaterialsUniformBufferID);
glBindBufferBase(GL_UNIFORM_BUFFER, 3, MaterialsUniformBufferID);

GLfloat Material[18];

//Diffuse
Material[0] = 0.5f;
Material[1] = 0.0f;
Material[2] = 0.0f;
Material[3] = 1.0f;

//Ambient
Material[4] = 0.2f;
Material[5] = 0.2f;
Material[6] = 0.2f;
Material[7] = 1.0f;

//Specular
Material[8] = 1.0f;
Material[9] = 1.0f;
Material[10] = 1.0f;
Material[11] = 1.0f;

//Emissive
Material[12] = 0.0f;
Material[13] = 0.0f;
Material[14] = 0.0f;
Material[15] = 1.0f;

//Shininess
Material[16] = 5.0f;

//Texture Count
Material[17] = 0.0f;

glBufferData(GL_UNIFORM_BUFFER, sizeof(Material), &Material, GL_DYNAMIC_DRAW);
glBindBuffer(GL_UNIFORM_BUFFER, NULL);

}@

[Chris Kawa]

Combining glew with Qt is a wasted effort as it duplicates functionality. The way to work with OpenGL in Qt is to make your GL class inherit e.g. QOpenGLFunctions_3_3_Core (or whichever version and profile you want to target), call initializeOpenGLFunctions() in the GL initialization function and then all the above GL calls become available in the class scope.