affine.h

file code.zip are used to implement ray tracing technology.

#ifndef _AFFINE_H
#define _AFFINE_H

#include <iostream>
using namespace std;

#include "common.h"

// @@@@@@@@@@@@@@@@@@@@@ Affine4 class @@@@@@@@@@@@@@@@ 
class Affine4 {// manages homogeneous affine transformations 
// including inverse transformations 
// and a stack to put them on 
// used by Scene class to read SDL files 
public: 
	float m[16]; // hold a 4 by 4 matrix 
	Affine4(){ // make identity transform 
		m[0] = m[5]  = m[10] = m[15] = 1.0; 
		m[1] = m[2]  = m[3]  = m[4]  = 0.0; 
		m[6] = m[7]  = m[8]  = m[9]  = 0.0; 
		m[11]= m[12] = m[13] = m[14] = 0.0; 
	} 
	void setIdentityMatrix(){ // make identity transform 
		m[0] = m[5]  = m[10] = m[15] = 1.0; 
		m[1] = m[2]  = m[3]  = m[4]  = 0.0; 
		m[6] = m[7]  = m[8]  = m[9]  = 0.0; 
		m[11]= m[12] = m[13] = m[14] = 0.0; 
	} 
	void set(Affine4 a)// set this matrix to a 
	{ 
		for(int i = 0; i < 16; i++) 
			m[i]=a.m[i]; 
	} 
	//<<<<<<<<<<<< postMult >>>>>>>>>>> 
	void postMult(Affine4 n){// postmultiplies this with n 
		float sum; 
		Affine4 tmp;  
		tmp.set(*this); // tmp copy 
		for(int c = 0; c < 4; c++)// form this = tmp * n 
			for(int r = 0; r <4 ; r++) 
			{ 
				sum = 0; 
				for(int k = 0; k < 4; k++) 
					sum += tmp.m[4 * k + r]* n.m[4 * c + k]; 
				m[4 * c + r] = sum; 
			}// end of for loops 
	}
	//<<<<<<<<<<<< preMult >>>>>>>>>>> 
	void preMult(Affine4 n){// premultiplies this with n 
		float sum; 
		Affine4 tmp;  
		tmp.set(*this); // tmp copy 
		for(int c = 0; c < 4; c++)// form this = n * tmp 
			for(int r = 0; r <4 ; r++) 
			{ 
				sum = 0; 
				for(int k = 0; k < 4; k++) 
					sum += n.m[4 * k + r]* tmp.m[4 * c + k]; 
				m[4 * c + r] = sum; 
			}// end of for loops 
	}
	void print(void) {
 	  for(int i=0; i<4; i++) {
	    for(int j=0; j<4; j++)
		cout <<m[i*4 + j]<<" ";
            cout<<endl;
	  }
	  return;
	}
	void applyTransform(float v[]) {
		float q[4];
		for(int i=0;i<4; i++) {
		   q[i] = 0;
		   for(int k=0; k < 4; k++) {
		      q[i] += m[4*k + i] * v[k];
		   }
   		}
		for(int ii=0; ii<4; ii++)
		   v[ii] = q[ii];
		return;
	}
			 
 
	void transpose(Affine4 &t)
	{
		for(int i=0; i < 4; i++)
			for(int j=0; j<4; j++)
				t.m[i*4 + j] = m[j*4 + i];

		return ;
	}
}; // end of Affine4 class 
 
//@@@@@@@@@@ AffineNode class @@@@@@@@@@@ 
class AffineNode{ 
// used by Scene class to read SDL files 
public: 
	Affine4 * affn; 
	Affine4 * invAffn; 
	AffineNode * next; 
	AffineNode() 
	{ 
		next = NULL; 
		affn = new Affine4; // new affine with identity in it 
		invAffn = new Affine4; // and for the inverse 
	} 
	~AffineNode() //destructor 
	{ 
		delete affn; 
		delete invAffn; 
	} 
}; 
//@@@@@@@@@@@@@@@@ AffineStack class @@@@@@@@@@@@ 
class AffineStack{ 
// used by Scene class to read SDL files 
public: 
	AffineNode * tos; 
	AffineStack()//default constructor;puts identity on top 
	{ 
		tos = new AffineNode; // node with identity in it 
		tos->next = NULL; 
	} 
	void dup() 
	{ 
		AffineNode* tmp = new AffineNode;			 
		tmp->affn = new Affine4(*(tos->affn)); 
		tmp->invAffn = new Affine4(*(tos->invAffn)); 
		tmp->next = tos; 
		tos = tmp; 
	} 
	void setIdentity() // make top item the identity matrix 
	{  
		assert(tos != NULL); 
		tos->affn->setIdentityMatrix(); 
		tos->invAffn->setIdentityMatrix(); 
	} 
	void popAndDrop() 
	{ 
		if(tos == NULL) return; // do nothing 
		AffineNode *tmp = tos; 
		tos = tos->next; 
		delete tmp; // should call destructor, which deletes trices 
	}	 
	void releaseAffines() 
	{ // pop and drop all remaining items  
	while(tos) popAndDrop();	
	} 
	void rotate(float angle, Vector3 u) 
	{ 
		Affine4 rm; // make identity matrix 
		Affine4 invRm; 
		u.normalize(); // make the rotation axis unit length 
		float ang = angle * 3.14159265/ 180; // deg to   
		float c = cos(ang), s = sin(ang); 
		float mc = 1.0 - c; 
	 	//fill the 3x3 upper left matrix - Chap.5 p. 29 
		rm.m[0] = c + mc * u.x * u.x; 
		rm.m[1] = mc * u.x * u.y + s * u.z; 
		rm.m[2] = mc * u.x * u.z - s * u.y; 
		rm.m[4] = mc * u.y * u.x - s * u.z; 
		rm.m[5] = c + mc * u.y * u.y; 
		rm.m[6] = mc * u.y * u.z + s * u.x; 
		rm.m[8] = mc * u.z * u.x + s * u.y; 
		rm.m[9] = mc * u.z * u.y - s * u.x; 
		rm.m[10] = c + mc * u.z * u.z; 
		// same for inverse : just sign of s is changed 
		invRm.m[0] = c + mc * u.x * u.x; 
		invRm.m[1] = mc * u.x * u.y - s * u.z; 
		invRm.m[2] = mc * u.x * u.z + s * u.y; 
		invRm.m[4] = mc * u.y * u.x + s * u.z; 
		invRm.m[5] = c + mc * u.y * u.y; 
		invRm.m[6] = mc * u.y * u.z - s * u.x; 
		invRm.m[8] = mc * u.z * u.x - s * u.y; 
		invRm.m[9] = mc * u.z * u.y + s * u.x; 
		invRm.m[10] = c + mc * u.z * u.z; 
		tos->affn->postMult(rm); 
		tos->invAffn->preMult(invRm); 
	} 
	void scale(float sx, float sy, float sz) 
	{ // post-multiply top item by scaling 
		#define sEps 0.00001 
		Affine4 scl;// make an identity 
		Affine4 invScl; 
		scl.m[0]  = sx;  
		scl.m[5]  = sy;  
		scl.m[10] = sz;// adjust it to a scaling matrix 
		if(fabs(sx) < sEps || fabs(sy) < sEps || fabs(sz) < sEps) 
		{ 
			cerr << "degenerate scaling transformation!\n";  
		} 
		invScl.m[0]  = 1/sx; invScl.m[5]  = 1/sy; invScl.m[10] = 1/sz; 
		tos->affn->postMult(scl); // 
		tos->invAffn->preMult(invScl); 
	}		 
	void translate(Vector3 d) 
	{ 
		Affine4 tr; // make identity matrix 
		Affine4 invTr; 
		tr.m[12] = d.x; tr.m[13] = d.y;	tr.m[14] = d.z; 
		invTr.m[12] = -d.x;	invTr.m[13] = -d.y; invTr.m[14] = -d.z; 
		tos->affn->postMult(tr); 
		tos->invAffn->preMult(invTr); 
	} 
}; 

#endif // _AFFINE_H