//========================================================
/**
*  @file      SkyBox.cpp
*
*  項目描述： 3DS文件載入
*  文件描述:  天空盒類  
*  適用平臺： Windows98/2000/NT/XP
*  
*  作者：     WWBOSS
*  電子郵件:  wwboss123@gmail.com
*  創建日期： 2006-12-06	
*  修改日期： 2006-12-10
*
*/     
//========================================================

#include "SkyBox.h"

	
CSkyBox::CSkyBox():length(750.0f),width(550.0f),height(400.0f),yRot(0.01f)
{	
}

CSkyBox::~CSkyBox()
{
	/** 刪除紋理對象及其占用的內存 */
	for(int i =0 ;i< 5; i++)
	{
		m_texture[i].FreeImage();
		glDeleteTextures(1,&m_texture[i].ID);
	}
	
}


/** 天空盒初始化 */
bool CSkyBox::init()
{
	char filename[128] ;                                         /**< 用來保存文件名 */
	char *bmpName[] = { "back","front","top","left","right"};
	for(int i=0; i< 5; i++)
	{
		sprintf(filename,"data/%s",bmpName[i]);
		strcat(filename,".bmp");
		if(!m_texture[i].LoadBitmap(filename))                     /**< 載入位圖文件 */
		{
			MessageBox(NULL,"裝載位圖文件失敗！","錯誤",MB_OK);    /**< 如果載入失敗則彈出對話框 */
			exit(0);
		}
		glGenTextures(1, &m_texture[i].ID);                        /**< 生成一個紋理對象名稱 */
		 
		glBindTexture(GL_TEXTURE_2D, m_texture[i].ID);             /**< 創建紋理對象 */
		/** 控制濾波 */
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
		glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL_CLAMP_TO_EDGE);
		glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL_CLAMP_TO_EDGE);
		/** 創建紋理 */
		gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGB, m_texture[i].imageWidth,
						m_texture[i].imageHeight, GL_RGB, GL_UNSIGNED_BYTE,
					    m_texture[i].image);
	}
	return true;
	
}


void CSkyBox::render()
{
	/** 獲得場景中光照狀態 */
	GLboolean lp;
	glGetBooleanv(GL_LIGHTING,&lp);

	m_CameraPos = Camera::GetCamera()->getPosition();

	glDisable(GL_LIGHTING);            /**< 關閉光照 */
	glEnable(GL_TEXTURE_2D);

	/** 開始繪制 */
	glPushMatrix();
	glTranslatef(m_CameraPos.x,m_CameraPos.y,m_CameraPos.z);

	glRotatef(yRot,0.0f,1.0f,0.0f);
			
	/** 繪制背面 */
	glBindTexture(GL_TEXTURE_2D, m_texture[0].ID);
    glBegin(GL_QUADS);		
		
		/** 指定紋理坐標和頂點坐標 */
		glTexCoord2f(1.0f, 0.0f); glVertex3f(  width, -height, -length);
		glTexCoord2f(1.0f, 1.0f); glVertex3f(  width,  height, -length); 
		glTexCoord2f(0.0f, 1.0f); glVertex3f( -width,  height, -length);
		glTexCoord2f(0.0f, 0.0f); glVertex3f( -width, -height, -length);
		
	glEnd();



	/** 繪制前面 */
	glBindTexture(GL_TEXTURE_2D, m_texture[1].ID);
	glBegin(GL_QUADS);	
	
		/** 指定紋理坐標和頂點坐標 */
		glTexCoord2f(1.0f, 0.0f); glVertex3f( -width, -height, length);
		glTexCoord2f(1.0f, 1.0f); glVertex3f( -width,  height, length);
		glTexCoord2f(0.0f, 1.0f); glVertex3f(  width,  height, length); 
		glTexCoord2f(0.0f, 0.0f); glVertex3f(  width, -height, length);

	glEnd();

	

	/** 繪制頂面 */
	glBindTexture(GL_TEXTURE_2D,  m_texture[2].ID);
	glBegin(GL_QUADS);		
		
	    /** 指定紋理坐標和頂點坐標 */
		glTexCoord2f(0.0f, 1.0f); glVertex3f(  width, height, -length);
		glTexCoord2f(0.0f, 0.0f); glVertex3f(  width, height,  length); 
		glTexCoord2f(1.0f, 0.0f); glVertex3f( -width, height,  length);
	    glTexCoord2f(1.0f, 1.0f); glVertex3f( -width, height, -length);
		
	glEnd();


	
	/** 繪制左面 */
	glBindTexture(GL_TEXTURE_2D, m_texture[3].ID);
	glBegin(GL_QUADS);		
		
		/** 指定紋理坐標和頂點坐標 */
		glTexCoord2f(1.0f, 1.0f);  glVertex3f( -width,  height,	-length);		
		glTexCoord2f(0.0f, 1.0f);  glVertex3f( -width,  height,  length); 
		glTexCoord2f(0.0f, 0.0f);  glVertex3f( -width, -height,  length);
		glTexCoord2f(1.0f, 0.0f);  glVertex3f( -width, -height, -length);	
		
	glEnd();

	/** 繪制右面 */
	glBindTexture(GL_TEXTURE_2D, m_texture[4].ID);
	glBegin(GL_QUADS);		

		/** 指定紋理坐標和頂點坐標 */
		glTexCoord2f(0.0f, 0.0f); glVertex3f( width, -height, -length);
		glTexCoord2f(1.0f, 0.0f); glVertex3f( width, -height,  length);
		glTexCoord2f(1.0f, 1.0f); glVertex3f( width,  height,  length); 
		glTexCoord2f(0.0f, 1.0f); glVertex3f( width,  height, -length);
	glEnd();
	

    glPopMatrix();                 /** 繪制結束 */

	if(lp)                         /** 恢復光照狀態 */  
		glEnable(GL_LIGHTING);

	glDisable(GL_TEXTURE_2D);

	 yRot += 0.01f;
	 if(yRot > 360.0f)
		 yRot = 0.0f;

	

}