Billboard Example

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relminator
Posts: 84
Joined: Sun Apr 11, 2010 10:43 am

Billboard Example

Post by relminator » Mon Aug 20, 2012 3:49 am

I noticed there is no billboading example in the package and searching the net resulted to nothing so I made this:

Code: Select all


/******************************************************************************
*******************************************************************************
	
	OpenGL BillBpoard Example
	Relminator (Richard Eric M. Lope)
	Http://Rel.Phatcode.Net
	
	Billboards are quads that are always Parallel to the screen.
	
	They always face the screen no matter how you transform your
	3D scene.
	
	Notice that the quads always face the screen even when the 3D scene
	rotates on all the axes.
	
	They are mainly used for HUDS, Particle effects, Trees, Sprites, etc.
	
	I made this out of necessity for a 2.5D game I'm working on and thought
	I might share it.
	
	Since the DS modelview matrix is a combo of Direction and Position,
	we only need the direction vectors to use billboards. Apparently,
	the Directional matrix is just a 3x3 matrix as oppposed to the
	Position matrix which is 4x4.
	
*******************************************************************************
******************************************************************************/ 
 
#include <nds.h>
#include <stdio.h>
#include <math.h>



// Just a vector3D class
class Vector3Df32
{
public:
	s32 x, y,z;
	
};


// Sets up some GL stuff
void InitGL()
{
   // initialize gl
	glInit();
	
	//enable textures
	glEnable( GL_TEXTURE_2D );
	
	// enable antialiasing
	glEnable( GL_ANTIALIAS );
		
	// setup the rear plane
	glClearColor( 0, 0, 0, 31 ); // BG must be opaque for AA to work
	glClearPolyID( 63 ); // BG must have a unique polygon ID for AA to work
	
	glClearDepth( GL_MAX_DEPTH );

	//this should work the same as the normal gl call
	glViewport(0,0,255,191);
	
	
	//any floating point gl call is being converted to fixed prior to being implemented
	glMatrixMode( GL_PROJECTION );

	glLoadIdentity();
	gluPerspective( 70, 256.0 / 192.0, 1, 200 );
	
	//not a real gl function and will likely change
	glPolyFmt( POLY_ALPHA(31) | POLY_CULL_BACK );
	
}


int main() 
{	

	
	//set mode 5, enable BG0 and set it to 3D
	videoSetMode( MODE_5_3D );
	
	consoleDemoInit();
	
	
	// initialize gl
	InitGL();
	
	// Print some console stuff
	iprintf("\x1b[1;1HBillboarding Example");
	iprintf("\x1b[3;1HRelminator");
	iprintf("\x1b[5;1HHttp://Rel.Phatcode.Net");
	
	
	// Parameters for our PQ torus
	s32 p = 0;
	s32 q = 100;
	
	// Billboad variables
	Vector3Df32 P0, P1, P2, P3; // Quad Coordinates needed to draw our billboards
	Vector3Df32 vUp, vRight;    // Orthogonal vectors for our directional matrix transforms
	s32 Matrix[9];				// Our 3x3 matrix to hold current diection
	
	// Size of each billboard
	v16 Size = floattov16(0.1);			
	
	int Frame = 0;				// just the standard frame counter
	
	// Right-handed system looks into -z
	gluLookAt(	0.0, 0.0, 1.0,		//camera position 
				0.0, 0.0, 0.0,		//look at
				0.0, 1.0, 0.0 );	//up
	
	while( 1 ) 
	{
	
		Frame++;
		
		// Animate PQ torus
		p++;
		q++;
		
		// We are drawing simple gouraud shaded billboards
		// so we disable texturing
		glDisable( GL_TEXTURE_2D );
		glBindTexture( GL_TEXTURE_2D, 0 );
	
		// So we don't mess with the above LookAt() transform
		glPushMatrix();
		
		// Reset current matrix
		glLoadIdentity();
		
		// Right-Handed so we translate negatively
		glTranslate3f32( 0, 0, floattof32(-5) );
		
		
		// Rotate our models on all axes
		glRotateXi( Frame * 20);
		glRotateYi( Frame * 40 );
		glRotateZi( Frame * 80 );
		
		// Get Matrix needed for billboards
		// Set current matrix to modelview
		glMatrixMode( GL_MODELVIEW );
		glGetFixed ( GL_GET_MATRIX_VECTOR, Matrix );  // Get current directional matrix
		
		
		// Copy orthogonal vectors
		vRight.x = Matrix[0];       // X Axis
		vRight.y = Matrix[3];
		vRight.z = Matrix[6];
		vUp.x = Matrix[1];			// Y Axis
		vUp.y = Matrix[4];
		vUp.z = Matrix[7];
		
		// Get quad points( f32 ) relative to (0,0,0)
		P0.x = ( (-vRight.x - vUp.x) * Size ) >> 12;   
		P0.y = ( (-vRight.y - vUp.y) * Size ) >> 12;
		P0.z = ( (-vRight.z - vUp.z) * Size ) >> 12;

		P1.x = ( ( vRight.x - vUp.x) * Size ) >> 12;
		P1.y = ( ( vRight.y - vUp.y) * Size ) >> 12;
		P1.z = ( ( vRight.z - vUp.z) * Size ) >> 12;

		P2.x = ( ( vRight.x + vUp.x) * Size ) >> 12;
		P2.y = ( ( vRight.y + vUp.y) * Size ) >> 12;
		P2.z = ( ( vRight.z + vUp.z) * Size ) >> 12;

		P3.x = ( (-vRight.x + vUp.x) * Size ) >> 12;
		P3.y = ( (-vRight.y + vUp.y) * Size ) >> 12;
		P3.z = ( (-vRight.z + vUp.z) * Size ) >> 12;
		
		
		// Draw 360 Billboarded Quads
		for( int i = 0; i < 360; i++)
		{
			// Fun with the PQ torus
			s32   r = ((5 + (sinLerp(q * i)))) * 4;		 
			s32   x = r * cosLerp(p * i);			  
			s32   y = r * cosLerp(q * i);
			s32   z = r * sinLerp(p * i);
			
			// Draw the billboards
			glPushMatrix();
		
				glTranslate3f32( x >> 12, y >> 12, z >> 12 );     // Move relative to( 0,0,-5)
				glBegin( GL_QUADS );	
				    glColor(RGB15(31, i & 31, i & 31));	// Play with colors
					glVertex3v16( P0.x, P0.y, P0.z );   // 1st coord
					
					glColor(RGB15(i & 31, 31, i & 31));	
					glVertex3v16( P1.x, P1.y, P1.z );
					
					glColor(RGB15(i & 31, i & 31, 31));	
					glVertex3v16( P2.x, P2.y, P2.z );
					
					glColor(RGB15(31 - i, 31- i, 31 - i));	
					glVertex3v16( P3.x, P3.y, P3.z );
				glEnd();
				
			
			glPopMatrix( 1 );
	
		}
		
		glPopMatrix( 1 );
	
		
		glFlush( 0 );

		swiWaitForVBlank();
	
		
	}

	return 0;


}//end main 




Feel free to add this in the 3D examples.

Here's the binary for the lazy:

http://rel.phatcode.net/junk.php?id=124

WinterMute
Site Admin
Posts: 1845
Joined: Tue Aug 09, 2005 3:21 am
Location: UK
Contact:

Re: Billboard Example

Post by WinterMute » Fri Aug 24, 2012 10:31 am

Nice, thanks for that - I'll definitely add that to the examples when I get a little time, hopefully soon.
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relminator
Posts: 84
Joined: Sun Apr 11, 2010 10:43 am

Re: Billboard Example

Post by relminator » Mon Aug 27, 2012 8:20 am

I forgot that that demo is quite useless w/o textures so here's a version with textures:

I used a 32x32x256 flares.bmp in this demo.

Code: Select all

/******************************************************************************
*******************************************************************************
	
	OpenGL BillBpoard Example
	Relminator (Richard Eric M. Lope)
	Http://Rel.Phatcode.Net
	
	Billboards are quads that are always Parallel to the screen.
	
	They always face the screen no matter how you transform your
	3D scene.
	
	Notice that the quads always face the screen even when the 3D scene
	rotates on all the axes.
	
	They are mainly used for HUDS, Particle effects, Trees, Sprites, etc.
	
	I made this out of necessity for a 2.5D game I'm working on and thought
	I might share it.
	
	Since the DS modelview matrix is a combo of Direction and Position,
	we only need the direction vectors to use billboards. Apparently,
	the Directional matrix is just a 3x3 matrix as oppposed to the
	Position matrix which is 4x4.
	
*******************************************************************************
******************************************************************************/ 
 
#include <nds.h>
#include <stdio.h>
#include <math.h>

#include "flares.h"


// Just a vector3D class
class Vector3Df32
{
public:
	s32 x, y,z;
	
};


// Sets up some GL stuff
void InitGL()
{
   // initialize gl
	glInit();
	
	//enable textures
	glEnable( GL_TEXTURE_2D );
	
	// enable antialiasing
	glEnable( GL_ANTIALIAS );
	
	
	
	// setup the rear plane
	glClearColor( 0, 0, 0, 31 ); // BG must be opaque for AA to work
	glClearPolyID( 63 ); // BG must have a unique polygon ID for AA to work
	
	glClearDepth( GL_MAX_DEPTH );

	//this should work the same as the normal gl call
	glViewport(0,0,255,191);
	
	
	//any floating point gl call is being converted to fixed prior to being implemented
	glMatrixMode( GL_PROJECTION );

	glLoadIdentity();
	gluPerspective( 70, 256.0 / 192.0, 1, 200 );
	
	//not a real gl function and will likely change
	glPolyFmt( POLY_ALPHA(31) | POLY_CULL_BACK );
	
	
	
}


int main() 
{	

	
	//set mode 5, enable BG0 and set it to 3D
	videoSetMode( MODE_5_3D );
	
	consoleDemoInit();
	
	
	// initialize gl
	InitGL();
	
	
	vramSetBankA(VRAM_A_TEXTURE);
	vramSetBankE(VRAM_E_TEX_PALETTE);  // Allocate VRAM bank for all the palettes
	
	
	int TextureID;
	
	glGenTextures(1, &TextureID);
	glBindTexture(0, TextureID);
	glTexImage2D(0, 0, GL_RGB256, TEXTURE_SIZE_32, TEXTURE_SIZE_32, 0, GL_TEXTURE_COLOR0_TRANSPARENT, (u8*)flaresBitmap);
	glColorTableEXT( 0, 0, flaresPalLen, 0, 0, (u16*)flaresPal );
	
	
	// Print some console stuff
	iprintf("\x1b[1;1HBillboarding Example");
	iprintf("\x1b[3;1HRelminator");
	iprintf("\x1b[5;1HHttp://Rel.Phatcode.Net");
	
	
	// Parameters for our PQ torus
	s32 p = 0;
	s32 q = 100;
	
	// Billboad variables
	Vector3Df32 P0, P1, P2, P3; // Quad Coordinates needed to draw our billboards
	Vector3Df32 vUp, vRight;    // Orthogonal vectors for our directional matrix transforms
	s32 Matrix[9];				// Our 3x3 matrix to hold current diection
	
	// Size of each billboard
	v16 Size = floattov16(0.1);			
	
	int Frame = 0;				// just the standard frame counter
	
	// Right-handed system looks into -z
	gluLookAt(	0.0, 0.0, 1.0,		//camera position 
				0.0, 0.0, 0.0,		//look at
				0.0, 1.0, 0.0 );	//up
	
	while( 1 ) 
	{
	
		Frame++;
		
		// Animate PQ torus
		p++;
		q++;
		
		glEnable( GL_TEXTURE_2D );
		glBindTexture(GL_TEXTURE_2D, TextureID);
		
		// So we don't mess with the above LookAt() transform
		glPushMatrix();
		
		// Reset current matrix
		glLoadIdentity();
		
		// Right-Handed so we translate negatively
		glTranslate3f32( 0, 0, floattof32(-5) );
		
		
		// Rotate our models on all axes
		glRotateXi( Frame * 20);
		glRotateYi( Frame * 40 );
		glRotateZi( Frame * 80 );
		
		// Get Matrix needed for billboards
		// Set current matrix to modelview
		glMatrixMode( GL_MODELVIEW );
		glGetFixed ( GL_GET_MATRIX_VECTOR, Matrix );  // Get current directional matrix
		
		
		// Copy orthogonal vectors
		vRight.x = Matrix[0];       // X Axis
		vRight.y = Matrix[3];
		vRight.z = Matrix[6];
		vUp.x = Matrix[1];			// Y Axis
		vUp.y = Matrix[4];
		vUp.z = Matrix[7];
		
		// Get quad points( f32 ) relative to (0,0,0)
		P0.x = ( (-vRight.x - vUp.x) * Size ) >> 12;   
		P0.y = ( (-vRight.y - vUp.y) * Size ) >> 12;
		P0.z = ( (-vRight.z - vUp.z) * Size ) >> 12;

		P1.x = ( ( vRight.x - vUp.x) * Size ) >> 12;
		P1.y = ( ( vRight.y - vUp.y) * Size ) >> 12;
		P1.z = ( ( vRight.z - vUp.z) * Size ) >> 12;

		P2.x = ( ( vRight.x + vUp.x) * Size ) >> 12;
		P2.y = ( ( vRight.y + vUp.y) * Size ) >> 12;
		P2.z = ( ( vRight.z + vUp.z) * Size ) >> 12;

		P3.x = ( (-vRight.x + vUp.x) * Size ) >> 12;
		P3.y = ( (-vRight.y + vUp.y) * Size ) >> 12;
		P3.z = ( (-vRight.z + vUp.z) * Size ) >> 12;
		
		
		// Draw 360 Billboarded Quads
		for( int i = 0; i < 360; i++)
		{
			// Fun with the PQ torus
			s32   r = ((5 + (sinLerp(q * i)))) * 4;		 
			s32   x = r * cosLerp(p * i);			  
			s32   y = r * cosLerp(q * i);
			s32   z = r * sinLerp(p * i);
			
			
			// Texcoords
			s32 u1 = 0 << 12;
			s32 u2 = 1 << 12;
			
			s32 v1 = 0 << 12;
			s32 v2 = 1 << 12;
			
			// Draw the billboards
			glPushMatrix();
		
				glTranslate3f32( x >> 12, y >> 12, z >> 12 );     // Move relative to( 0,0,-5)
				glBegin( GL_QUADS );	
				    glColor(RGB15(31, i & 31, i & 31));	// Play with colors
					glTexCoord2f32( u1, v2 );
					glVertex3v16( P0.x, P0.y, P0.z );   // 1st coord
					
					glColor(RGB15(i & 31, 31, i & 31));	
					glTexCoord2f32( u2, v2 );
					glVertex3v16( P1.x, P1.y, P1.z );
					
					glColor(RGB15(i & 31, i & 31, 31));	
					glTexCoord2f32( u2, v1 );
					glVertex3v16( P2.x, P2.y, P2.z );
					
					glColor(RGB15(31 - i, 31- i, 31 - i));	
					glTexCoord2f32( u1, v1 );
					glVertex3v16( P3.x, P3.y, P3.z );
				glEnd();
				
			
			glPopMatrix( 1 );
	
		}
		
		glPopMatrix( 1 );
	
		
		glFlush( 0 );

		swiWaitForVBlank();
	
		
	}

	return 0;


}//end main 





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