OpenGL Not drawing
I am using GLFW as GUI for OpenGL projects. I am using my red book and testing code and well the first bit of code doesn't work at all. I want to say this is a GLFW problem because I don't have this problem in JOGL.
#include <iostream>
#include "GL/glfw.h"
#ifndef MAIN
#define MAIN
#include "GL/gl.h"
#include "GL/glu.h"
#endif
using namespace std;
int main()
{
int running = GL_TRUE;
glfwInit();
if( !glfwOpenWindow( 300,300, 0,0,0,0,0,0, GLFW_WINDOW ) )
{
glfwTerminate();
return 0;
}
while( running )
{
//GL Code here
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0.0, 0.0, 0.0, 0.0);
glColor3f(1.0, 1.0, 1.0);
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
开发者_高级运维glVertex3f(0.25, 0.25, 0.0);
glVertex3f(0.75, 0.25, 0.0);
glVertex3f(0.75, 0.75, 0.0);
glVertex3f(0.25, 0.75, 0.0);
glEnd();
glFlush();
glfwSwapBuffers();
// Check if ESC key was pressed or window was closed
running = !glfwGetKey( GLFW_KEY_ESC ) &&
glfwGetWindowParam( GLFW_OPENED );
}
glfwTerminate();
return 0;
}
Adding glLoadIdentity();
fixed the code:
#include <iostream>
#include "GL/glfw.h"
#ifndef MAIN
#define MAIN
#include "GL/gl.h"
#include "GL/glu.h"
#endif
using namespace std;
int main()
{
int running = GL_TRUE;
glfwInit();
if( !glfwOpenWindow( 640,480, 0,0,0,0,0,0, GLFW_WINDOW ) )
{
glfwTerminate();
return 0;
}
while( running )
{
//GL Code here
glLoadIdentity();
glClearColor(0.0, 0.0, 0.0, 0.0);
glClearDepth(1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glColor3f(1.0, 1.0, 1.0);
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
glBegin(GL_POLYGON);
glVertex3f(0.25, 0.25, 0.0);
glVertex3f(0.75, 0.25, 0.0);
glVertex3f(0.75, 0.75, 0.0);
glVertex3f(0.25, 0.75, 0.0);
glEnd();
glFlush();
glfwSwapBuffers();
// Check if ESC key was pressed or window was closed
running = !glfwGetKey( GLFW_KEY_ESC ) &&
glfwGetWindowParam( GLFW_OPENED );
}
glfwTerminate();
return 0;
}
you must specify wich matrix you want the glOrtho to transform
.....
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
......
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