void cParticleSystem::Draw(void){
	cParticle *index = head;

	glEnable(GL_TEXTURE_2D);
	glEnable(GL_BLEND);
	glDisable(GL_LIGHTING);
	
	glBindTexture(GL_TEXTURE_2D, texture[0]);
	glBlendFunc( GL_SRC_ALPHA, GL_ONE );

	if (renderMethod == CPU_BILLBOARDS){
		double mat[16];
		glGetDoublev( GL_MODELVIEW_MATRIX, mat );
		cVector3 right(mat[0], mat[4], mat[8]);
		cVector3 up(mat[1], mat[5], mat[9]);
		cVector3 point0, point1, point2, point3;

		while (index){
			cVector3 point0 = index->position + (((-right) - up) * index->size );
			cVector3 point1 = index->position + ((right - up) * index->size );
			cVector3 point2 = index->position + ((right + up) * index->size );
			cVector3 point3 = index->position + (((-right) + up) * index->size );

			cVector3 color;
			if (index->life > 1.0){
				double percent = ((index->life - 1.0) / (index->startLife - 1.0));
				double oneMinusPercent = 1.0 - percent;
				color = (startColor * percent) + (endColor * oneMinusPercent);
			}else{
				color = endColor;
			}

			glColor4d(color.x, color.y, color.z, index->life);

			glBegin(GL_QUADS);
			glTexCoord2d(0, 0); glVertex3f(point0.x, point0.y, point0.z);
			glTexCoord2d(1, 0); glVertex3f(point1.x, point1.y, point1.z);
			glTexCoord2d(1, 1); glVertex3f(point2.x, point2.y, point2.z);
			glTexCoord2d(0, 1); glVertex3f(point3.x, point3.y, point3.z);
			glEnd();

			index = index->next;
		}
	}else if( renderMethod == ARB_POINT_SPRITES ){
		float quadratic[] =  { 1.0f, 0.0f, 0.01f };
		glPointParameterfvARB( GL_POINT_DISTANCE_ATTENUATION_ARB, quadratic );

		glPointParameterfARB( GL_POINT_FADE_THRESHOLD_SIZE_ARB, 60.0f );

		glPointParameterfARB( GL_POINT_SIZE_MIN_ARB, 1.0f );
		glPointParameterfARB( GL_POINT_SIZE_MAX_ARB, index->size );

		glTexEnvf( GL_POINT_SPRITE_ARB, GL_COORD_REPLACE_ARB, GL_TRUE );

		glEnable( GL_POINT_SPRITE_ARB );
		
		while( index ){
			glPointSize( index->size );
	
			cVector3 color;
			if (index->life > 1.0){
				double percent = ((index->life - 1.0) / (index->startLife - 1.0));
				double oneMinusPercent = 1.0 - percent;
				color = (startColor * percent) + (endColor * oneMinusPercent);
			}else{
				color = endColor;
			}
	
			glColor4d(color.x, color.y, color.z, index->life);
			glBegin( GL_POINTS );
				glVertex3d( index->position.x, index->position.y, index->position.z);
				index = index->next;
			glEnd();
		}

		glDisable( GL_POINT_SPRITE_ARB );
	}else if( renderMethod == CG_VERTEX_SHADER ){
		cParticle  *index = head;

        // Compute billboard vertices on the GPU...
        // Track the combined model-view-projection matrix
		cgGLSetStateMatrixParameter( m_CGparam_modelViewProj,
									 CG_GL_MODELVIEW_PROJECTION_MATRIX,
									 CG_GL_MATRIX_IDENTITY );

        // Load the billboard size into a constant register
        //float fSize[] = { 1.0f, 0.0f, 0.0f, 0.0f };
        //cgGLSetParameter4fv( m_CGparam_size, fSize );

        // Create a pre-rotated quad for use by the shader...

		float mat[16];
		glGetFloatv( GL_MODELVIEW_MATRIX, mat );

		cVector3f vRight( mat[0], mat[4], mat[8] );
		cVector3f vUp( mat[1], mat[5], mat[9] );
		cVector3f vCenter( 0.0f, 0.0f, 0.0f );

		cVector3f vPoint0 = vCenter + (-vRight - vUp);
		cVector3f vPoint1 = vCenter + ( vRight - vUp);
		cVector3f vPoint2 = vCenter + ( vRight + vUp);
		cVector3f vPoint3 = vCenter + (-vRight + vUp);

		float preRotatedQuad[16] = {
			vPoint0.x, vPoint0.y, vPoint0.z, 0.0f,
			vPoint1.x, vPoint1.y, vPoint1.z, 0.0f,
			vPoint2.x, vPoint2.y, vPoint2.z, 0.0f,
			vPoint3.x, vPoint3.y, vPoint3.z, 0.0f
		};

		cgGLSetParameterArray4f( m_CGparam_preRotatedQuad, 0, 4, preRotatedQuad );

        // Bind the shader and render the particles...
		cgGLBindProgram( m_CGprogram );
		cgGLEnableProfile( m_CGprofile );

		glBindTexture( GL_TEXTURE_2D, texture[0] );

		float fAdjustedSize = index->size;

		glBegin( GL_QUADS );{
			while( index ){
				cVector3 color;
				if (index->life > 1.0){
					double percent = ((index->life - 1.0) / (index->startLife - 1.0));
					double oneMinusPercent = 1.0 - percent;
					color = (startColor * percent) + (endColor * oneMinusPercent);
				}else{
					color = endColor;
				}
	
				glColor4d(color.x, color.y, color.z, index->life);

				vCenter.x = index->position.x;
				vCenter.y = index->position.y;
				vCenter.z = index->position.z;
                
				glTexCoord4f( 0.0f, 0.0f, 0.0f, fAdjustedSize );
				glVertex3f( vCenter.x, vCenter.y, vCenter.z );

				glTexCoord4f( 1.0f, 0.0f, 1.0f, fAdjustedSize );
				glVertex3f( vCenter.x, vCenter.y, vCenter.z );

				glTexCoord4f( 1.0f, 1.0f, 2.0f, fAdjustedSize );
				glVertex3f( vCenter.x, vCenter.y, vCenter.z );

				glTexCoord4f( 0.0f, 1.0f, 3.0f, fAdjustedSize );
				glVertex3f( vCenter.x, vCenter.y, vCenter.z );

				index = index->next;
			}
		}
		glEnd();

		cgGLDisableProfile( m_CGprofile );
	}
}