I'm extremely new to OpenGL, but not game design (i used to use SDL). Is there any way to draw directly to the screen to do a HUD without having to use glTranslate or glRotate or anything else. Either opengl doesn't do this or I'm just looking through the wrong functions. Any insight would be awsome Ozwald~

Search for the millions of threads about 2d using OpenGL. The same method can be used to draw a hud over your 3d scene.

it's simple, use glOrtho and the turn off depthwriting and depthtesting with
glDisable(GL_DEPTH_TEST);
glDepthMask(GL_FALSE);
and you have a good hud drawing mode.

also you can use these functions to help switching back and forth between the different modes.



you might still have to use glTranslate (you won't get away from that in openGL) but it's definitly a lot easier to draw the hud in this mode.

thanks, lc_overlord. That did the trick very nicely.

Ozwald~

does anyone know how to output variables to the HUD like the score
Thanks
AC

just print what you want to the screen...here's a routine from nehe's tutorial for printing...works just like printf in c

GLvoid glPrint(GLuint glfontlist, GLfloat x, GLfloat y, const char *fmt, ...){	if( glIsList( glfontlist ) == GL_FALSE ) {		// Error Report?		return;	}		glRasterPos2f( x, y );		char text[256];	va_list ap;		if(fmt==NULL) return;		va_start(ap, fmt);		vsprintf(text, fmt, ap);	va_end(ap);		glPushAttrib(GL_LIST_BIT);	glListBase(glfontlist - 32);	glCallLists(strlen(text), GL_UNSIGNED_BYTE, text);	glPopAttrib();}

it uses lists for the font...if you look through nehe's tutorials, and find some of the font/printing text tutorials, you find how to load such.

hope that helps.

Oz~

PS:

int score = 50;glPrint( yourfont, 1.0f, 500.0f, "Your score is: %d", score );

I'm having a problem.

I'm drawing a polygon in perspective view then switching over to ortho view to render text. I can display text but only by using openGL coordinates in an ortho view by using RasterPos2i(x,y)

I want to display my text using Windows coordinates like in the Lesson 32 program on nehe.gavedev.net.

The code to set up perspective is here
______________________________________

void SetupViewPorts(int width, int height)
{
// now setup the viewports
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION); // set projection matrix
glLoadIdentity(); // reset projection matrix

// calculate aspect ratio of window
gluPerspective(45.0f, (GLfloat)width/(GLfloat)height,1.0f,1000.0f);

glMatrixMode(GL_MODELVIEW); // set modelview matrix
glLoadIdentity(); // reset modelview matrix
}
-------------------------------------------------------------------------
and my rendering code which renders in the viewport created in previous function
a polygon, then switches over to ortho and renders the text
-------------------------------------------------------------------------
// fuction for rendering
void Render()
{

char output[50] = " ";
char output2[50] = " ";
char ch_zoom[50];

// clear screen and depth buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity(); // reset modelview matrix



// move one unit into the screen
glTranslatef(0.0f, 0.0f, zoom);
glPushMatrix();
glRotatef(angle, 1.0f, 0.0f, 0.0f);
glRotatef(angle, 0.0f, 1.0f, 0.0f);
glRotatef(angle, 0.0f, 0.0f, 1.0f);
glBegin(GL_QUADS);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(-1.0f, -1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(1.0f, -1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(1.0f, 1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(-1.0f, 1.0f, 0.0);
glEnd();
glPopMatrix();




// setup ortho view to draw text
glPushMatrix();

glMatrixMode(GL_PROJECTION);

glOrtho(0, winWidth, 0, winTop, -1, 1);
glMatrixMode(GL_MODELVIEW);
glColor4f(1.0f, 1.0f, 1.0f, 0.75f);

glRasterPos2i(-4, -4);
// build the string
gcvt(zoom, 4, ch_zoom);
strcpy(output, "Zoom is currently: ");
strcpy(output2, ch_zoom);
strcat(output, output2);

PrintString(listbase, output);

glFlush();
SwapBuffers(g_HDC); // bring back buffer to foreground
angle += 0.01f;
if(angle >= 360.0f)
angle = 0.0f;

}
___________________________________________________________________

can someone help me fix this code and clean it up so I can render my text using windows coordinate system like the nehe.gamedev.net Lesson 32 program?
___________________________________________________________________

The coordinates using ortho mode should be the same as the window coordinates (as in if the res is 800x600, x goes 0-800, y goes 0-600)
If you want true windows coords, use ScreenToClient( hWnd, POINT coords );
or ClientToScreen( <same parameters> );

Oz~

PS:

glOrtho(0, winWidth, winTop, 0, -1, 1);

that should fix it :p

here is my complete code. Maybe you can figure it out.

____________________________________________________________________________
#define WIN32_LEAN_AND_MEAN

#include
#include
#include
#include
#include
#include

// global variables
bool keyPressed[256]; // holds true for keys that are pressed
float angle = 0.0f; // current angle of the rotating triangle
HDC g_HDC; // global device context
HWND g_HWND;

bool b_fullScreen = TRUE; // flag value to test for full screen mode

unsigned int listbase;

int winHeight, winWidth, winTop, winBottom; // rect structure to store window values
float zoom = -10.0f;

// Prototype Functions
void SetupFont();
void Render();
void SetupFullScreenMode();
void SetupViewPorts(int width, int height);
unsigned int CreateBitmapFont(char *fontName, int fontSize);
void PrintString(unsigned int base, char *str);
void ClearFont(unsigned int base);
void Initialize();

// End Prototypes
void Initialize()
{
glClearColor(0.0f, 0.0f, 0.0f, 0.0f); // clear to black

glShadeModel(GL_SMOOTH);
glEnable(GL_DEPTH_TEST);

listbase = CreateBitmapFont("Comic Sans MS", 20); // create the bitmap font
}


unsigned int CreateBitmapFont(char *fontName, int fontSize)
{
HFONT hFont; // windows font
unsigned int base;

base = glGenLists(96); // create storage for 96 characters

if(stricmp(fontName, "symbol") == 0)
{
hFont = CreateFont(fontSize, 0, 0, 0, FW_BOLD, FALSE, FALSE, FALSE, SYMBOL_CHARSET,
OUT_TT_PRECIS, CLIP_DEFAULT_PRECIS, ANTIALIASED_QUALITY,
FF_DONTCARE | DEFAULT_PITCH, fontName);
}
else
{
hFont = CreateFont(fontSize, 0, 0, 0, FW_BOLD, FALSE, FALSE, FALSE, ANSI_CHARSET,
OUT_TT_PRECIS, CLIP_DEFAULT_PRECIS, ANTIALIASED_QUALITY,
FF_DONTCARE | DEFAULT_PITCH, fontName);
}
if(!hFont)
{
MessageBox(NULL, "Failed to Create Font!", "Font Error", MB_OK);
return 0;
}

SelectObject(g_HDC, hFont);
wglUseFontBitmaps(g_HDC, 32, 96, base);

return base;
}

void PrintString(unsigned int base, char *str)
{
glDisable(GL_DEPTH_TEST);
if((base == 0) || (str == NULL))
return;

glPushAttrib(GL_LIST_BIT);
glListBase(base -32);
glCallLists(strlen(str), GL_UNSIGNED_BYTE, str);
glPopAttrib();
glEnable(GL_DEPTH_TEST);
}

void ClearFont(unsigned int base)
{
if(base != 0)
glDeleteLists(base, 96);
}



void SetupViewPorts(int width, int height)
{
// now setup the viewports
glViewport(0, 0, width, height);
glMatrixMode(GL_PROJECTION); // set projection matrix
glLoadIdentity(); // reset projection matrix

// calculate aspect ratio of window
gluPerspective(45.0f, (GLfloat)width/(GLfloat)height,1.0f,1000.0f);

glMatrixMode(GL_MODELVIEW); // set modelview matrix
glLoadIdentity(); // reset modelview matrix
}


//function that sets up fullscreen mode
void SetupFullScreenMode()
{
// do nothing
MessageBox(NULL, "Full screen mode not available yet!", "Fullscreen?", MB_OK);
b_fullScreen = FALSE;
}


// fuction for rendering
void Render()
{

char output[50] = " ";
char output2[50] = " ";
char ch_zoom[50];

// clear screen and depth buffer
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity(); // reset modelview matrix



// move one unit into the screen
glTranslatef(0.0f, 0.0f, zoom);
glPushMatrix();
glRotatef(angle, 1.0f, 0.0f, 0.0f);
glRotatef(angle, 0.0f, 1.0f, 0.0f);
glRotatef(angle, 0.0f, 0.0f, 1.0f);
glBegin(GL_QUADS);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(-1.0f, -1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(1.0f, -1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(1.0f, 1.0f, 0.0);
glColor3f(1.0f,0.0f,0.0f);
glVertex3f(-1.0f, 1.0f, 0.0);
glEnd();
glPopMatrix();




// setup ortho view to draw text
glPushMatrix();

glMatrixMode(GL_PROJECTION);

glOrtho(0, winWidth, winTop, 0, -1, 1);
glMatrixMode(GL_MODELVIEW);
glColor4f(1.0f, 1.0f, 1.0f, 0.75f);

glRasterPos2i(-4,-4);
// build the string
gcvt(zoom, 4, ch_zoom);
strcpy(output, "Zoom is currently: ");
strcpy(output2, ch_zoom);
strcat(output, output2);

PrintString(listbase, output);

glFlush();
SwapBuffers(g_HDC); // bring back buffer to foreground
angle += 0.01f;
if(angle >= 360.0f)
angle = 0.0f;

}

// function to set the pixel format for the device context
void SetupPixelFormat(HDC hDC)
{
int nPixelFormat; // your pixel format

static PIXELFORMATDESCRIPTOR pfd = {
sizeof(PIXELFORMATDESCRIPTOR), // size of the structure
1, // version, always set to 1
PFD_DRAW_TO_WINDOW | // support window
PFD_SUPPORT_OPENGL | // support OpenGL
PFD_DOUBLEBUFFER, // support double buffering
PFD_TYPE_RGBA, // RGBA color mode
32, // go for 32 bit color mode
0, 0, 0, 0, 0, 0, // ignore color bits, not used
0, // no alpha buffer
0, // ignore shift bit
0, // no accumulation bits
0, 0, 0, 0, // ignore accumulation bits
16, // 16 bit z-buffer size
0, // no stencil buffer
0, // no auxiliary buffer
PFD_MAIN_PLANE, // main drawing plane
0, // reserved
0, 0, 0 }; // layer masks ignored

//choose best matching pixel format, return index
nPixelFormat = ChoosePixelFormat(hDC, &pfd);

// set pixel format to device context
SetPixelFormat(hDC, nPixelFormat, &pfd);
}

// the windows Procedure event handler
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
static HGLRC hRC; // rendering context
static HDC hDC; // device context
char string[] = "Hello world!"; // text to be displayed
int width, height; // window width and height
RECT myWinDimensions;



switch(message)
{
case WM_CREATE: // window is being created

listbase = CreateBitmapFont("Comic Sans MS", 48);
if(MessageBox(NULL, "Do you want to run in fullscreen mode?", "Fullscreen?", MB_YESNO) == IDYES)
{
SetupFullScreenMode();
}
else
{
MessageBox(NULL, "Running in windowed mode", "Fullscreen?", MB_OK);
}
hDC = GetDC(hwnd); // get device context for window
g_HDC = hDC;
SetupPixelFormat(hDC); // call your pixel format setup function

// create rendering context and make it current
hRC = wglCreateContext(hDC); // create rendering context
wglMakeCurrent(hDC, hRC); // make rendering context current
return 0;
break;

case WM_DESTROY: // window is closing
wglMakeCurrent(hDC, NULL); // deselect Rendering context
wglDeleteContext(hRC); // delete rendering context
ClearFont(listbase);
PostQuitMessage(0);
return 0;
break;

case WM_SIZE:
height = HIWORD(lParam); // retrieve width and height
width = LOWORD(lParam);

if (height == 0) // dont want a divied by zero
{
height = 1;
}
g_HWND = hwnd;
SetupViewPorts(width, height);



return 0;
break;

case WM_KEYDOWN:
SetCapture(hwnd);
// is a key pressed?
keyPressed[wParam] = true;
return 0;
break;
case WM_KEYUP:
ReleaseCapture();
keyPressed[wParam] = false;
return 0;
break;


default:
break;
}

return (DefWindowProc(hwnd, message, wParam, lParam));
}

// The application entry point
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
WNDCLASSEX windowClass; // window class
HWND hwnd; // window handle
MSG msg; // message
bool done; // flag saying when your app is complete

DWORD my_exstyle, my_style;

// fill out the window class structure
windowClass.cbSize = sizeof(WNDCLASSEX);
windowClass.style = CS_HREDRAW | CS_VREDRAW;
windowClass.lpfnWndProc = WndProc;
windowClass.cbClsExtra = 0;
windowClass.cbWndExtra = 0;
windowClass.hInstance = hInstance;
windowClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);
windowClass.hCursor = LoadCursor(NULL, IDC_ARROW);
windowClass.hbrBackground = (HBRUSH)GetStockObject(WHITE_BRUSH);
windowClass.lpszMenuName = NULL;
windowClass.lpszClassName = "MyClass";
windowClass.hIconSm = LoadIcon(NULL, IDI_WINLOGO);

// register the window class
if (!RegisterClassEx(&windowClass))
return 0;

if (b_fullScreen)
{
my_exstyle = WS_EX_APPWINDOW; // hide top level windows
my_style = WS_POPUP; // no border on your window
ShowCursor(TRUE); // hide the cursor
}
else
{
my_exstyle = WS_EX_APPWINDOW | WS_EX_WINDOWEDGE; // same as regular window
my_style = WS_OVERLAPPEDWINDOW;
}
// class registered, so now create your window
hwnd = CreateWindowEx(NULL,
"MyClass",
"Bitmap Fonts Application in OpenGL",
WS_OVERLAPPEDWINDOW |
WS_VISIBLE |
WS_SYSMENU,
100, 100,
400, 400,
NULL,
NULL,
hInstance,
NULL);

// check if window creation failed( hwnd would equal NULL)
if (!hwnd)
return 0;

ShowWindow(hwnd, SW_SHOW); // display the window
UpdateWindow(hwnd); // update the window

Initialize();
// main message loop
while(true)
{
if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
// Process the message
if (msg.message == WM_QUIT)
break;
TranslateMessage(&msg);
DispatchMessage(&msg);
}
else
{
if (keyPressed[VK_ESCAPE])
PostQuitMessage(0);
if (keyPressed['A'])
{
zoom += 0.01f;
}
if (keyPressed['Z'])
{
zoom -= 0.01f;
}
// Render Here
Render(); // Call rendering Function
}

}



return msg.wParam;
}
_______________________________________________________________________________