//Raycaster.h

#ifndef RAYCASTER_H
#define RAYCASTER_H

#include <glm\glm.hpp>

class Raycaster
{
public:
	Raycaster(glm::vec3 p, glm::vec3 p_dir);
	glm::ivec3 getNextVoxel();
private:
	glm::vec3 pos;
	glm::vec3 dir;
	bool xplus;
	bool yplus;
	bool zplus;
};

#endif


//Raycaster.cpp
#include "Raycaster.h"

Raycaster::Raycaster(glm::vec3 p, glm::vec3 p_dir)
{
	pos = p;
	dir = p_dir;
	xplus = true;
	yplus = true;
	zplus = true;
	if (dir.x < 0)
		xplus = false;
	if (dir.y < 0)
		yplus = false;
	if (dir.z < 0)
		zplus = false;
}

glm::ivec3 Raycaster::getNextVoxel()
{
	int nextX = (int) pos.x;
	int nextY = (int) pos.y;
	int nextZ = (int) pos.z;
	if (xplus)
		nextX++;
	if (yplus)
		nextY++;
	if (zplus)
		nextZ++;
	float distanceX = nextX - pos.x;
	float distanceY = nextY - pos.y;
	float distanceZ = nextZ - pos.z;
	float qx = distanceX / dir.x;
	float qy = distanceY / dir.y;
	float qz = distanceZ / dir.z;

	//The qx/y/z+=0.000001; is a quick and dirty solution 
	//to enable the continuation of the raycast.
	if (qx <= qy && qx <= qz)
	{
		qx+=0.000001;
		pos += qx * dir;
	}
	else if (qy <= qx && qy <= qz)
	{
		qy+=0.000001;
		pos += qy * dir;
	}
	else if (qz <= qx && qz <= qy)
	{
		qz+=0.000001;
		pos += qz * dir;
	}

	return glm::ivec3( (int) pos.x, (int) pos.y, (int) pos.z);

}

Traverses unit cubes given a starting position and direction vector.

Voxel Raycaster

C++