tree.cpp

c++程序

// Tree.cpp: Implementierung der Klasse CTree.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "Tree.h"

//////////////////////////////////////////////////////////////////////
// Konstruktion/Destruktion
//////////////////////////////////////////////////////////////////////

CTree::CTree()
{
	// Init member variables
	m_PosX = 0.0f;
	m_PosY = 0.0f;
	m_PosZ = 0.0f;
	m_TreeSize = 0.4f;
	m_TextureIndex = 0;
	m_DistanceToViewer = 0.0f;
}

CTree::~CTree()
{

}

void CTree::DrawTree(float fYRotation)
{
	// Draw the tree
	
	glBegin(GL_QUADS);
		glTexCoord2f(0.0f, 0.0f);
		glVertex3f(-m_TreeSize, 0.0f, 0.0f);
		glTexCoord2f(1.0f, 0.0f);
		glVertex3f(m_TreeSize, 0.0f, 0.0f);
		glTexCoord2f(1.0f, 1.0f);
		glVertex3f(m_TreeSize, 2.0f * m_TreeSize, 0.0f);
		glTexCoord2f(0.0f, 1.0f);
		glVertex3f(-m_TreeSize, 2.0f * m_TreeSize, 0.0f);
	glEnd();
}

void CTree::CalculateDistance(float fXViewer, float fYViewer, float fZViewer)
{
	// Calculate the distance from the tree to the viewer. The result is saved
	// in the member data

	// Don't call sqrt() for performance reasons. This doesn't calculate the
	// real distance, but the value could be used for depth comparisations
	m_DistanceToViewer = (fXViewer - m_PosX) * (fXViewer - m_PosX) + 
						 (fYViewer - m_PosY) * (fYViewer - m_PosY) + 
						 (fZViewer - m_PosZ) * (fZViewer - m_PosZ);
}