Need help with drawing Multiple models?

Hey guys,

I've started learning OpenGL through Nehe's tutorial. I was playing around with the code of tutorial # 31 which basically loads and draws a model. I modfied the code and drew a chessboard and i'm having 2 problems. First, i tried to draw multiple models but every time when i run the program only one of the Models is drawn. It seems the second Models doesn't apper or maybe something else which i don't know how to solve.
Second, I can't draw my chess piece on the chess board. The chess piece model is always drawn behind the chess board.
Here is the code for reference:

Code:

pModel -> drawChessBoard();	// Draw The chess board	
	// Draw The Models	
	glTranslatef(-270.0f, -50.0f, -640.0f);		
	bPawn -> draw();
	glTranslatef(-350.0f, -50.0f, -640.0f);		
	wPawn -> draw();

I'm beginner please someone help me? I would really apperciate. Thanks in advance

Regards,

Salu

Try this, tell me if it works. Otherwise post more code/information (the model's drawing routine would be nice).

Code:

glPushMatrix();
pModel -> drawChessBoard();	// Draw The chess board	
glPopMatrix();
	// Draw The Models	
glPushMatrix();
	glTranslatef(-270.0f, -50.0f, -640.0f);		
	bPawn -> draw();
glPopMatrix();

glPushMatrix();
	glTranslatef(-350.0f, -50.0f, -640.0f);		
	wPawn -> draw();
glPopMatrix();

Thanks for the reply now i can draw multiple models but my 2nd problem is still not solved . I still can't draw the model(s) on the chess board. They are always drawn behind the board. Any other ideas? I would really Apperciate the help.

BobMcGee123 bro if you need the code to how to draw a model check below website tutorial # 31: http://nehe.gamedev.net/

Post a screenshot of what you mean by behind the chessboard, I think you just need to alter the coordinates.

Here are: the screen shot and the code of how the chessboard is drawn, the coordinates and other stuff. In the screen shot there are 2 models the brown we can see but the blue one is drawn behind the chessboard. I'm keeping it's one part outside so you can see what do i mean?

Code:

 
void Model:: initChessBoardBStripes(GLfloat x, GLfloat y) {
	
   glLoadIdentity();	
   glPushMatrix();
		
       glTranslatef(-4.0f + x, -4.0f + y, 0.0f);		
       texture[0] = LoadGLTexture("Data/black.bmp" );	
		
       glBegin(GL_TRIANGLE_STRIP);
	glTexCoord2f(0.0f, 0.0f);glVertex3f(0.0f, 0.0f, -12.0f);
	glTexCoord2f(1.0f, 0.0f);glVertex3f(1.0f, 0.0f, -12.0f);
	glTexCoord2f(0.0f, 1.0f);glVertex3f(0.0f, 1.0f, -12.0f);
	glTexCoord2f(1.0f, 1.0f);glVertex3f(1.0f, 1.0f, -12.0f);
        glEnd();
			
   glPopMatrix( );	
}

void Model:: initChessBoardWStripes(GLfloat x, GLfloat y) {
	
   glLoadIdentity();	
   glPushMatrix();
   
          glTranslatef(-3.0f + x, -4.0f + y, 0.0f);		
          texture[0] = LoadGLTexture("Data/white.bmp" );
		
          glBegin(GL_TRIANGLE_STRIP);
	glTexCoord2f(0.0f, 0.0f);glVertex3f(0.0f, 0.0f, -12.0f);
	glTexCoord2f(1.0f, 0.0f);glVertex3f(1.0f, 0.0f, -12.0f);
	glTexCoord2f(0.0f, 1.0f);glVertex3f(0.0f, 1.0f, -12.0f);
	glTexCoord2f(1.0f, 1.0f);glVertex3f(1.0f, 1.0f, -12.0f);
           glEnd();
			
   glPopMatrix();	
}

void Model:: drawChessBoard() {
		
   for (int i = 1; i < 65; i++) {
	 if (i <= 8) {
	    if (i % 2 == 0)		
		initChessBoardWStripes(0.0f + i - 2, 0.0f);
	    else
		initChessBoardBStripes(0.0f + i - 1, 0.0f);

	} else if (i > 8 && i <= 16) {									
	    if (i % 2 == 0)		
		initChessBoardBStripes(1.0f + i - 10, 1.0f);
 	    else
		initChessBoardWStripes(-1.0f + i - 9, 1.0f);

	}else if (i > 16 && i <= 24) {									
	    if (i % 2 == 0)		
		initChessBoardWStripes(0.0f + i - 18, 2.0f);
	    else
		initChessBoardBStripes(0.0f + i - 17, 2.0f);

	} else if (i > 24 && i <= 32) {											
	    if (i % 2 == 0)		
		initChessBoardBStripes(1.0f + i - 26, 3.0f);
	   else
	               initChessBoardWStripes(-1.0f + i - 25, 3.0f);

	}else if (i > 32 && i <= 40) {									
	   if (i % 2 == 0)		
		initChessBoardWStripes(0.0f + i - 34, 4.0f);
	   else
		initChessBoardBStripes(0.0f + i - 33, 4.0f);

	}else if (i > 40 && i <= 48) {									
	   if (i % 2 == 0)		
		initChessBoardBStripes(1.0f + i - 42, 5.0f);
	   else
	                initChessBoardWStripes(-1.0f + i - 41, 5.0f);

	}else if (i > 48 && i <= 56) {									
	   if (i % 2 == 0)		
		initChessBoardWStripes(0.0f + i - 50, 6.0f);
	   else
		initChessBoardBStripes(0.0f + i - 49, 6.0f);

	}else if (i > 56 && i <= 64) {									
	    if (i % 2 == 0)		
		initChessBoardBStripes(1.0f + i - 58, 7.0f);
	    else
		initChessBoardWStripes(-1.0f + i - 57, 7.0f);
	}		
    }	
}

Thanks in advance!!

I dunno what order you are drawing the pieces in, but try enabling depth testing.

Originally Posted by Jeremy G

I dunno what order you are drawing the pieces in, but try enabling depth testing.

I've already tried that it didn't work. Here is the code Jermey in the main class where everything is drawn.

Code:

int DrawGLScene(GLvoid)  {
        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);			// Clear The Screen And The Depth Buffer
        glLoadIdentity();	// Reset The Modelview Matrix
		

       glPushMatrix();
	pModel -> drawChessBoard();	// Draw The chess board	
       glPopMatrix();
	
       // Draw The Models	
       glPushMatrix();
	glTranslatef(-220.0f, -50.0f, -640.0f);		
	bPawn -> draw();
       glPopMatrix();

       glPushMatrix();
	glTranslatef(-330.0f, -50.0f, -640.0f);		
	wPawn -> draw();
       glPopMatrix();
	
return TRUE;	// Keep Going
}

Any other ideas guys pleas help me?

Draw the board first thing.

Thanks guys i've figured out the porblem. Actually it wasn't that hard. The depth of the board was far less than the depth of the chess piece. so it was always drawn behind the chess board but i've solved it. Thanks though!!

Yep it was a coordinate problem !