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View Full Version : can't translate objects/prmitives along x-axis



carlton1212
08-22-2011, 06:07 PM
I can translate objects along the x and y axis by passing variables to them that are incremented or decremented by 0.05 upon pressing the a,d or space bar. But when i try to translate along the z-axis with the same glTranslatef function nothing happens. well it just doesn't render it depending on the value i put in the z parameter. I have listed my code below. Im trying to stimulate "camera" movement in the 3d world and it works even though i haven't set up a PROJECTIONS mode with the glMartrixMode function or haven't set up a camera.

I want to think that since there is no camera moving along the z-axis with any large amount the object or primitive is rendered out of view giving the appearance of a blank scene. If you guys could help me with setting up the camera or just get it where i can translate objects along the z-axis to stimulate movement then that would be great. And also as you can see from my code im having a hard time rotating the camera on its point (or technically...rotating the world around the cameras point.) also i try to set up my rendering code in a seperate function "drawNewScene" outside of the winmain function but nothing is rendered and if it is it is only for a second.


/**************************
* Includes
*
**************************/

#include <windows.h>
#include <gl/gl.h>
#include <GL/glut.h>


/**************************
* Function Declarations
*
**************************/

LRESULT CALLBACK WndProc (HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam);
void EnableOpenGL (HWND hWnd, HDC *hDC, HGLRC *hRC);
void DisableOpenGL (HWND hWnd, HDC hDC, HGLRC hRC);
double INzpos, INxpos, INypos, INRypos;



/**************************
* WinMain
*
**************************/

int WINAPI WinMain (HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int iCmdShow)
{
WNDCLASS wc;
HWND hWnd;
HDC hDC;
HGLRC hRC;
MSG msg;
BOOL bQuit = FALSE;
INzpos= 0.0;
INxpos= 0.0;
INypos= 0.0;
INRypos= 0.0;

/* register window class */
wc.style = CS_OWNDC;
wc.lpfnWndProc = WndProc;
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInstance;
wc.hIcon = LoadIcon (NULL, IDI_APPLICATION);
wc.hCursor = LoadCursor (NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH) GetStockObject (BLACK_BRUSH);
wc.lpszMenuName = NULL;
wc.lpszClassName = "GLSample";
RegisterClass (&amp;wc);

/* create main window */
hWnd = CreateWindow (
"GLSample", "OpenGL Sample",
WS_CAPTION | WS_POPUPWINDOW | WS_VISIBLE,
0, 0, 1300, 760,
NULL, NULL, hInstance, NULL);

/* enable OpenGL for the window */
EnableOpenGL (hWnd, &amp;hDC, &amp;hRC);

/* program main loop */
while (!bQuit)
{
/* check for messages */
if (PeekMessage (&amp;msg, NULL, 0, 0, PM_REMOVE))
{
/* handle or dispatch messages */
if (msg.message == WM_QUIT)
{
bQuit = TRUE;
}
else
{
TranslateMessage (&amp;msg);
DispatchMessage (&amp;msg);
}
}
else
{
/* OpenGL animation code goes here */



/* Program entry point */



glViewport(0, 0, 1300, 760);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(5.0, 5.0, -1.0, 1.0, 2.0, 100.0);

glMatrixMode(GL_MODELVIEW);
glLoadIdentity() ;
glClearColor (0.0f, 0.0f, 0.0f, 0.0f);
glLoadIdentity();
glClear (GL_COLOR_BUFFER_BIT);

glPushMatrix ();

glTranslatef(INxpos, 0.0, INzpos);
glBegin (GL_TRIANGLES);
glColor3f (1.0f, 0.0f, 0.0f); glVertex3f (0.0f, 1.0f, 0.0f);
glColor3f (0.0f, 1.0f, 0.0f); glVertex3f (0.87f, -0.5f, 0.0f);
glColor3f (0.0f, 0.0f, 1.0f); glVertex3f (-0.87f, -0.5f, 0.0f);
glEnd ();
glPopMatrix ();

SwapBuffers (hDC);
Sleep (1);

}
}

/* shutdown OpenGL */
DisableOpenGL (hWnd, hDC, hRC);

/* destroy the window explicitly */
DestroyWindow (hWnd);

return msg.wParam;
}


/********************
* Window Procedure
*
********************/

LRESULT CALLBACK WndProc (HWND hWnd, UINT message,
WPARAM wParam, LPARAM lParam)
{

switch (message)
{
case WM_CREATE:
return 0;
case WM_CLOSE:
PostQuitMessage (0);
return 0;

case WM_DESTROY:
return 0;

case WM_KEYDOWN:
switch (wParam)
{
case VK_ESCAPE:
PostQuitMessage(0);
return 0;
case 'w':
INzpos = INzpos - 0.9;
return 0;
case 'D':
INxpos = INxpos - 0.051;
return 0;
case 'A':
INxpos = INxpos + 0.05;
return 0;
case 'S':
INzpos = INzpos + 0.05;
return 0;
case VK_SPACE:
INypos = INypos + 0.015;
return 0;
case 'J':
INRypos = INRypos + 10.0;
INxpos = INxpos + 0.02;
}
return 0;

default:
return DefWindowProc (hWnd, message, wParam, lParam);
}
}


/*******************
* Enable OpenGL
*
*******************/

void EnableOpenGL (HWND hWnd, HDC *hDC, HGLRC *hRC)
{
PIXELFORMATDESCRIPTOR pfd;
int iFormat;

/* get the device context (DC) */
*hDC = GetDC (hWnd);

/* set the pixel format for the DC */
ZeroMemory (&amp;pfd, sizeof (pfd));
pfd.nSize = sizeof (pfd);
pfd.nVersion = 1;
pfd.dwFlags = PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER;
pfd.iPixelType = PFD_TYPE_RGBA;
pfd.cColorBits = 24;
pfd.cDepthBits = 16;
pfd.iLayerType = PFD_MAIN_PLANE;
iFormat = ChoosePixelFormat (*hDC, &amp;pfd);
SetPixelFormat (*hDC, iFormat, &amp;pfd);

/* create and enable the render context (RC) */
*hRC = wglCreateContext( *hDC );
wglMakeCurrent( *hDC, *hRC );

}


/******************
* Disable OpenGL
*
******************/

void DisableOpenGL (HWND hWnd, HDC hDC, HGLRC hRC)
{
wglMakeCurrent (NULL, NULL);
wglDeleteContext (hRC);
ReleaseDC (hWnd, hDC);
}


nevermind to rotate objects around a point im guessing you just rotate the object first then translate it because doing translating it then rotating it would just cause it to move to its new position then rotate on the spot.

MaxH
08-22-2011, 10:12 PM
What happens when you run the code you posted without pushing any buttons? What do you see?