Displaying a 2d HUD onto a 3d display?

glMatrixMode( GL_MODELVIEW );
glLoadIdentity( );
glMatrixMode( GL_PROJECTION );
glLoadIdentity( );

glOrtho( 0, screen_width, screen_height, 0, -1, 1 );

glBindTexture( GL_TEXTURE_2D, tex);

glBegin( GL_QUADS );
glTexCoord2i( 0, 0 );
glVertex2i( hud_x, hud_y );
glTexCoord2i( 1, 0 );
glVertex2i( hud_x+hud_width, hud_y );
glTexCoord2i( 1, 1 );
glVertex2i( hud_x+hud_width, hud_y+hud_height );
glTexCoord2i( 0, 1 );
glVertex2i( hud_x, hud_y+hud_height );
glEnd( );

The important part of this code is the call to glOrtho, which basically sets up opengl to draw in 2d. In this case, using screen_width and screen_height set up the coordinate system to use pixels in a 1:1 manner with the screen. glOrtho can also do other stuff, so check the docs on it.

Edit: forgot glBindTexture. And now that I think about it, the texture coords in my pseudocode are probably vertically flipped.

[edited by - Melekor on May 21, 2004 11:13:59 PM]

screenwidth/2 - hudwidth/2
screenwidth/2 + hudwidth/2

screenheight/2 - hudheight/2;
screenheight/2 + hudheight/2;

will center the hud on screen

Thanks that displayed the image fine
Oh and yes I hade to swap it around to the following:
glOrtho(0,screen_width,0,screen_height,-1,1);
i.e. Bottom Left is (0,0)

The only problem now is I have tried to used the same sort of code in another function of my code but I cannot get it to display lines using the follwing coed
Sorry for the long code and I know it''s a bit messy

This if from my dll that I am creating...
Which draws a Bar Graph like in Winamp of the music/sounds being played.

It all was fine when I didnt use the new above code.

SPECTRUM_API void SPECTRUM_DrawVU2 (void)
{
int e_bnd=0,b0=0,BANDS=64,j=0,k=0; // 0 = 32 band and 1 = 64 band.
int red,green,blue,alpha=100;

float vuX,vuY;
long x;
float gap=7.915f; // for default
double equVal,y1=0;
float AV_peak_falloff = 0.8f; // Spead the Peaks fall.

int n;

// Screen Size.
int screen_width = 800;
int screen_height = 600;

// Set Image Size.
int hud_width = 406;
int hud_height = 112;

// Start pos of image.
int hud_x = 10;
int hud_y = 25;

glEnable(GL_BLEND);
glEnable(GL_TEXTURE_2D);

// Select Our VU Meter Background Texture
glBindTexture(GL_TEXTURE_2D, SPEC_texture[0]);
glPushAttrib(GL_LIGHTING_BIT | GL_TRANSFORM_BIT);

glDisable(GL_LIGHTING);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
glOrtho(0,screen_width,0,screen_height,-1,1); // Set Up An Ortho Screen
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glEnable(GL_BLEND);
glBegin(GL_QUADS);
glTexCoord2i(0, 0); glVertex2i(hud_x, hud_y);
glTexCoord2i(1, 0 ); glVertex2i( hud_x+hud_width, hud_y );
glTexCoord2i( 1, 1 ); glVertex2i( hud_x+hud_width, hud_y+hud_height );
glTexCoord2i( 0, 1 ); glVertex2i( hud_x, hud_y+hud_height );
glEnd();
glDisable(GL_BLEND);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glPopAttrib();
glDisable(GL_TEXTURE_2D);
glDisable(GL_BLEND);
// End of Background image code.

// Now for the VU Bars Section.
BASS_ChannelGetData(SPEC_chan,SPEC_FFT2048,BASS_DATA_FFT2048);
if (SPEC_band64) {e_bnd=1;BANDS=128;}
for (x=0;x {
float sum=0;
int sc,b1=int(pow(2,x*10.0/(BANDS-1)));
if (b1>1023) b1=1023;
if (b1<=b0) b1=b0+1; // make sure it uses at least 1 FFT bin
sc=10+b1-b0;
for (;b0 equVal=(sqrt(sum/log10(sc))*1.7*SPECHEIGHT)-4; // scale it

if(equVal<0.0f) equVal=0.0f;
if(equVal>100.0f) equVal=100.0f;

//Comment out the line below to display audio levels.
equVal=70; // Force the VU level to 70%

if(equVal>=70){red=255; green=0; blue=0;}
else if(equVal>=50){red=255; green=255; blue=0;}
else if(equVal>=20){red=5; green=255; blue=0;}
else{red=0; green=255; blue=0;}

if (SPEC_band64) glLineWidth(2.0f);
else glLineWidth(5.0f);
glEnable(GL_BLEND);
glBegin(GL_LINES);
SPEC_gl_Color4d(red, green, blue,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))), (equVal/200.0f)*0.09f);

if(equVal>=50)
{
SPEC_gl_Color4d(255, 255, 0,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))), ((equVal/1.25)/200.0f)*0.09f);
SPEC_gl_Color4d(255, 255, 0,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))), ((equVal/1.25)/200.0f)*0.09f);

SPEC_gl_Color4d(127, 255, 0,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))), ((equVal/1.5)/200.0f)*0.09f);

SPEC_gl_Color4d(127, 255, 0,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))), ((equVal/1.5)/200.0f)*0.09f);
}

SPEC_gl_Color4d (0, 255, 0,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))) , 0.0f);
glEnd();

if(equVal>=SPEC_equVal2[x]) SPEC_equVal2[x] = float(equVal);
if(SPEC_equVal2[x]>0.0f) SPEC_equVal2[x] = SPEC_equVal2[x] -AV_peak_falloff;
if(SPEC_equVal2[x]<0.0f) SPEC_equVal2[x]=0.0f;

glBegin(GL_LINES);
SPEC_gl_Color4d(255, 255, 255,255);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))),((SPEC_equVal2[x]+1.6f)/200.0f)*0.09f);
glVertex2d( x/ (pow(double(2.0f),double(gap+(1.0f*e_bnd)))),((SPEC_equVal2[x])/200.0f)*0.09f);
glEnd();
glDisable(GL_BLEND);
}
}

I hope this displays ok, and is enough info

This should display something like the following Image:
VU Bar Graph

[edited by - TheMightyDude on May 22, 2004 2:20:14 PM]

It''s ok I have figuared it out

I have done it the same way I had done the displaying of the 2d image with some slight code changing but the bars/lines seemed to be a bit dim/dark so I had to glDisable(GL_TEXTURE_2D); before I did the displaying of the bars/lines