Hello, I want to learn OpenGL 4. I tried to use GLEW and GL3W, then I got similar error. The GLEW program’s:
#include <stdlib.h>#include <stdio.h>
#include <string.h>
#include <GL/glew.h>
#include <GL/freeglut.h>
#define WINDOW_TITLE_PREFIX "Chapter 2"
int
CurrentWidth = 800,
CurrentHeight = 600,
WindowHandle = 0;
unsigned FrameCount = 0;
GLuint
VertexShaderId,
FragmentShaderId,
ProgramId,
VaoId,
VboId,
ColorBufferId;
const GLchar* VertexShader =
{
"#version 400
"\
"layout(location=0) in vec4 in_Position;
"\
"layout(location=1) in vec4 in_Color;
"\
"out vec4 ex_Color;
"\
"void main(void)
"\
"{
"\
" gl_Position = in_Position;
"\
" ex_Color = in_Color;
"\
"}
"
};
const GLchar* FragmentShader =
{
"#version 400
"\
"in vec4 ex_Color;
"\
"out vec4 out_Color;
"\
"void main(void)
"\
"{
"\
" out_Color = ex_Color;
"\
"}
"
};
void Initialize(int, char*]);
void InitWindow(int, char*]);
void ResizeFunction(int, int);
void RenderFunction(void);
void TimerFunction(int);
void IdleFunction(void);
void Cleanup(void);
void CreateVBO(void);
void DestroyVBO(void);
void CreateShaders(void);
void DestroyShaders(void);
int main(int argc, char* argv])
{
Initialize(argc, argv);
glutMainLoop();
exit(EXIT_SUCCESS);
}
void Initialize(int argc, char* argv])
{
GLenum GlewInitResult;
InitWindow(argc, argv);
glewExperimental = GL_TRUE;
GlewInitResult = glewInit();
if (GLEW_OK != GlewInitResult) {
fprintf(
stderr,
"ERROR: %s
",
glewGetErrorString(GlewInitResult)
);
exit(EXIT_FAILURE);
}
fprintf(
stdout,
"INFO: OpenGL Version: %s
",
glGetString(GL_VERSION)
);
CreateShaders();
CreateVBO();
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
}
void InitWindow(int argc, char* argv])
{
glutInit(&argc, argv);
glutInitContextVersion(4, 0);
glutInitContextFlags(GLUT_FORWARD_COMPATIBLE);
glutInitContextProfile(GLUT_CORE_PROFILE);
glutSetOption(
GLUT_ACTION_ON_WINDOW_CLOSE,
GLUT_ACTION_GLUTMAINLOOP_RETURNS
);
glutInitWindowSize(CurrentWidth, CurrentHeight);
glutInitDisplayMode(GLUT_DEPTH | GLUT_DOUBLE | GLUT_RGBA);
WindowHandle = glutCreateWindow(WINDOW_TITLE_PREFIX);
if(WindowHandle < 1) {
fprintf(
stderr,
"ERROR: Could not create a new rendering window.
"
);
exit(EXIT_FAILURE);
}
glutReshapeFunc(ResizeFunction);
glutDisplayFunc(RenderFunction);
glutIdleFunc(IdleFunction);
glutTimerFunc(0, TimerFunction, 0);
glutCloseFunc(Cleanup);
}
void ResizeFunction(int Width, int Height)
{
CurrentWidth = Width;
CurrentHeight = Height;
glViewport(0, 0, CurrentWidth, CurrentHeight);
}
void RenderFunction(void)
{
++FrameCount;
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glDrawArrays(GL_TRIANGLES, 0, 6);
glutSwapBuffers();
}
void IdleFunction(void)
{
glutPostRedisplay();
}
void TimerFunction(int Value)
{
if (0 != Value) {
char* TempString = (char*)
malloc(512 + strlen(WINDOW_TITLE_PREFIX));
sprintf(
TempString,
"%s: %d Frames Per Second @ %d x %d",
WINDOW_TITLE_PREFIX,
FrameCount * 4,
CurrentWidth,
CurrentHeight
);
glutSetWindowTitle(TempString);
free(TempString);
}
FrameCount = 0;
glutTimerFunc(250, TimerFunction, 1);
}
void Cleanup(void)
{
DestroyShaders();
DestroyVBO();
}
void CreateVBO(void)
{
GLfloat Vertices] = {
-0.8f, 0.8f, 0.0f, 1.0f,
0.8f, 0.8f, 0.0f, 1.0f,
-0.8f, -0.8f, 0.0f, 1.0f,
-0.8f, -0.8f, 0.0f, 1.0f,
0.8f, 0.8f, 0.0f, 1.0f,
0.8f, -0.8f, 0.0f, 1.0f
};
GLfloat Colors] = {
1.0f, 0.0f, 0.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 0.0f, 1.0f, 1.0f,
0.0f, 1.0f, 0.0f, 1.0f,
1.0f, 1.0f, 1.0f, 1.0f
};
GLenum ErrorCheckValue = glGetError();
glGenVertexArrays(1, &VaoId);
glBindVertexArray(VaoId);
glGenBuffers(1, &VboId);
glBindBuffer(GL_ARRAY_BUFFER, VboId);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(0);
glGenBuffers(1, &ColorBufferId);
glBindBuffer(GL_ARRAY_BUFFER, ColorBufferId);
glBufferData(GL_ARRAY_BUFFER, sizeof(Colors), Colors, GL_STATIC_DRAW);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(1);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not create a VBO: %s
",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void DestroyVBO(void)
{
GLenum ErrorCheckValue = glGetError();
glDisableVertexAttribArray(1);
glDisableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glDeleteBuffers(1, &ColorBufferId);
glDeleteBuffers(1, &VboId);
glBindVertexArray(0);
glDeleteVertexArrays(1, &VaoId);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not destroy the VBO: %s
",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void CreateShaders(void)
{
GLenum ErrorCheckValue = glGetError();
VertexShaderId = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(VertexShaderId, 1, &VertexShader, NULL);
glCompileShader(VertexShaderId);
FragmentShaderId = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(FragmentShaderId, 1, &FragmentShader, NULL);
glCompileShader(FragmentShaderId);
ProgramId = glCreateProgram();
glAttachShader(ProgramId, VertexShaderId);
glAttachShader(ProgramId, FragmentShaderId);
glLinkProgram(ProgramId);
glUseProgram(ProgramId);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not create the shaders: %s
",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
void DestroyShaders(void)
{
GLenum ErrorCheckValue = glGetError();
glUseProgram(0);
glDetachShader(ProgramId, VertexShaderId);
glDetachShader(ProgramId, FragmentShaderId);
glDeleteShader(FragmentShaderId);
glDeleteShader(VertexShaderId);
glDeleteProgram(ProgramId);
ErrorCheckValue = glGetError();
if (ErrorCheckValue != GL_NO_ERROR)
{
fprintf(
stderr,
"ERROR: Could not destroy the shaders: %s
",
gluErrorString(ErrorCheckValue)
);
exit(-1);
}
}
The used command’s:
g++ -o the_program -lGLEW -lglut file.cpp
The error’s:
/usr/lib64/gcc/x86_64-suse-linux/4.8/…/…/…/…/x86_64-suse-linux/bin/ld: /tmp/ccrJgTa8.o: undefined reference to symbol ‘glClear’/usr/lib64/gcc/x86_64-suse-linux/4.8/…/…/…/…/x86_64-suse-linux/bin/ld: note: ‘glClear’ is defined in DSO /usr/X11R6/lib64/libGL.so.1 so try adding it to the linker command line
/usr/X11R6/lib64/libGL.so.1: could not read symbols: Invalid operation
collect2: error: ld returned 1 exit status
In case of GL3W, I hope I did it the right way. I moved gl3w.h and glcorearb.h to /usr/include/GL and the compiled the files test.c*, which comes with the GL3W source,* with:
g++ -o the_test -lglut -L/usr/include/GL/gl3w.h test.c
The error was:
/tmp/cc8zHajU.o: In function
display()':test.c:(.text+0x3f): undefined reference togl3wClearColor’
test.c:(.text+0x92): undefined reference togl3wClear' /tmp/cc8zHajU.o: In functionreshape(int, int)‘:
test.c:(.text+0xe9): undefined reference togl3wViewport' test.c:(.text+0x108): undefined reference togl3wClearDepth’
test.c:(.text+0x119): undefined reference togl3wClearColor' test.c:(.text+0x12e): undefined reference togl3wEnable’
/tmp/cc8zHajU.o: In functionmain': test.c:(.text+0x1a3): undefined reference togl3wInit’
test.c:(.text+0x1e0): undefined reference togl3wIsSupported' test.c:(.text+0x215): undefined reference togl3wGetString’
test.c:(.text+0x226): undefined reference to `gl3wGetString’
collect2: error: ld returned 1 exit status
