#include <OpenGL/gl.h> // Header File For The OpenGL32 Library
#include <OpenGL/glu.h> // Header File For The GLu32 Library
#include <GLUT/glut.h> // Header File For The GLut Library
#define kWindowWidth 640
#define kWindowHeight 480
// Function Prototypes
GLvoid InitGL(GLvoid);
GLvoid DrawGLScene(GLvoid);
GLvoid ReSizeGLScene(int Width, int Height);
void glEnable2D();
void glDisable2D();
void RenderScene();
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize (kWindowWidth, kWindowHeight);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
InitGL();
glutDisplayFunc(DrawGLScene);
glutReshapeFunc(ReSizeGLScene);
glutMainLoop();
RenderScene();
return 0;
}
GLvoid DrawGLScene(GLvoid){}
GLvoid InitGL(GLvoid){}
GLvoid ReSizeGLScene(int Width, int Height)
{}
void glEnable2D()
{
int vPort[4];
glGetIntegerv(GL_VIEWPORT, vPort);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(vPort[0], vPort[0]+vPort[2], vPort[1], vPort[1]+vPort[3], -1, 1);
glMatrixMode(GL_MODELVIEW);
glPushMatrix();
glLoadIdentity();
glTranslatef(0.375, 0.375, 0.);
glPushAttrib(GL_DEPTH_BUFFER_BIT);
glDisable(GL_DEPTH_TEST);
}
void glDisable2D()
{
glPopAttrib();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
glPopMatrix();
}
void RenderScene()
{
glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glEnable2D();
glBegin(GL_TRIANGLES);
glColor3ub(255, 0, 0);
glVertex2d(0, 0);
glColor3ub(0, 255, 0);
glVertex2d(100,0);
glColor3ub(0, 0, 255);
glVertex2D(50, 50);
glEnd();
glDisable2D();
}
RenderScene() doesn't render
November 06, 2004 01:01 PM
Shouldn't this render a triangle?
I'm not really sure what I am missing. I'm compiling on XCode 1.2, Mac OS X 10.3.6
206
November 06, 2004 01:05 PM
Since you're using double buffering, you need to swap the buffers. Add the function call glutSwapBuffers() to the end of your RenderScene function.
November 06, 2004 01:12 PM
Hi, I added what you said, but still no triangle, unless it is rendering a white triangle on a white background.
These are the warnings I am getting:
1) Passing arg 2 of glGetIntegerv from incompatible pointer type
2) implicit declaration of function 'glVertex2D'
Following your instructions the RenderScene() is now:
These are the warnings I am getting:
1) Passing arg 2 of glGetIntegerv from incompatible pointer type
2) implicit declaration of function 'glVertex2D'
Following your instructions the RenderScene() is now:
void RenderScene(){ glClear(GL_COLOR_BUFFER_BIT| GL_DEPTH_BUFFER_BIT); glLoadIdentity(); glEnable2D(); glBegin(GL_TRIANGLES); glColor3ub(255, 0, 0); glVertex2d(0, 0); glColor3ub(0, 255, 0); glVertex2d(100,0); glColor3ub(0, 0, 255); glVertex2D(50, 50); glEnd(); glDisable2D(); glutSwapBuffers();}
378
November 06, 2004 01:14 PM
Try calling RenderScene() in your DrawGLScene() function, because that's the display callback you told GLUT to use while in the glutMainLoop(). If I remember correctly, there is no need to call RenderScene() after glutMainLoop() because the later will only return execution when the window is destroyed.
206
November 06, 2004 01:17 PM
The second warning refers to your calling glVertex2D (as opposed to glVertex2d, remember C/C++ are case-sensitive). This is certainly something to fix. The first warning is referring to using int instead of GLint.
Edit: And aldenar is right ( I wasn't paying attention). You should call RenderScene() in DrawGLScene, and remove the glutSwapBuffers from the RenderScene, and replace it in DrawGLScene.
Edit: And aldenar is right ( I wasn't paying attention). You should call RenderScene() in DrawGLScene, and remove the glutSwapBuffers from the RenderScene, and replace it in DrawGLScene.
November 06, 2004 01:20 PM
Ok, doing that I get
Zerolink: unknown symbol '_glVertex2D'
App has exited due to signal 6 (SIGABRT)
GLvoid DrawGLScene(GLvoid)
{
RenderScene();
}
Zerolink: unknown symbol '_glVertex2D'
App has exited due to signal 6 (SIGABRT)
GLvoid DrawGLScene(GLvoid)
{
RenderScene();
}
206
November 06, 2004 01:24 PM
Quote: Original post by Jiroh
Ok, doing that I get
Zerolink: unknown symbol '_glVertex2D'
App has exited due to signal 6 (SIGABRT)
GLvoid DrawGLScene(GLvoid)
{
RenderScene();
}
All of the calls should be glVertex2d, not glVertex2D
November 06, 2004 01:24 PM
Hi, thanks for the tips. It now renders a triangle at the bottom left corner of screen.
So that much is cool, I now need to understand this code. Maybe I can alter it to change the trianle shape and position.
Thanks!
So that much is cool, I now need to understand this code. Maybe I can alter it to change the trianle shape and position.
Thanks!
This topic is closed to new replies.
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