Raycast

//Location is a struct defined as "double x, y, z;"
Location rayLoc = campos.location, mapLoc, rayDir, glNear, glFar, raySideDist, rayDeltaDist, rayStepDist;

//Have we hit a voxel, or is the ray too long?
bool hasCollided = false, tooLong = false;
//How many steps we've taken and how many we should take
int rayIterations = 0, maxIterations = 32;
//What side we hit
int side = 0;
//OpenGL pointers for direction calculation
GLdouble modelview[16], projection[16];
GLint viewport[4];

//mapLoc should be all integers, representing a voxel in the world
mapLoc.x = roundf(rayLoc.x);
mapLoc.y = roundf(rayLoc.y);
mapLoc.z = roundf(rayLoc.z);

std::cout << "Raypos is [" << rayLoc.x << " " << rayLoc.y << " " << rayLoc.z << "]";
std::cout << ", but rounding to [" << mapLoc.x << " " << mapLoc.y << " " << mapLoc.z << "]\n";

//Get pointers for the matrices and unproject to get our direction
glGetDoublev(GL_MODELVIEW_MATRIX, modelview);
glGetDoublev(GL_PROJECTION_MATRIX, projection);
glGetIntegerv(GL_VIEWPORT, viewport);

gluUnProject(400, 300, 0, modelview, projection, viewport, &glNear.x, &glNear.y, &glNear.z);
gluUnProject(400, 300, 1, modelview, projection, viewport, &glFar.x, &glFar.y, &glFar.z);

rayDir.x = glFar.x - glNear.x;
rayDir.y = glFar.y - glNear.y;
rayDir.z = glFar.z - glNear.z;

std::cout << "Orientation: [" << campos.orientation.x << " " << campos.orientation.y << " " << campos.orientation.z << "]\n";
std::cout << "Calculated vectors: [" << rayDir.x << " " << rayDir.y << " " << rayDir.z << "]\n";

//Calculations for step distance, distance to next axis side, and distance to next voxel side
if(rayDir.x == 0)
{
    rayStepDist.x = 0;
    rayDeltaDist.x = rayDir.x;
    raySideDist.x = (rayLoc.x - mapLoc.x) * rayDeltaDist.x;
}
else if(rayDir.x < 0)
{
    rayStepDist.x = -1;
    rayDeltaDist.x = rayStepDist.x / rayDir.x;
    raySideDist.x = (rayLoc.x - mapLoc.x) * rayDeltaDist.x;
}
else
{
    rayStepDist.x = 1;
    rayDeltaDist.x = rayStepDist.x / rayDir.x;
    raySideDist.x = ((mapLoc.x + 1) - rayLoc.x) * rayDeltaDist.x;
}

if(rayDir.z == 0)
{
    rayStepDist.z = 0;
    rayDeltaDist.z = rayDir.z;
    raySideDist.z = (rayLoc.z - mapLoc.z) * rayDeltaDist.z;
}
else if(rayDir.z < 0)
{
    rayStepDist.z = -1;
    rayDeltaDist.z = rayStepDist.z / rayDir.z;
    raySideDist.z = (rayLoc.z - mapLoc.z) * rayDeltaDist.z;
}
else
{
    rayStepDist.z = 1;
    rayDeltaDist.z = rayStepDist.z / rayDir.z;
    raySideDist.z = ((mapLoc.z + 1) - rayLoc.z) * rayDeltaDist.z;
}

if(rayDir.y == 0)
{
    rayStepDist.y = 0;
    rayDeltaDist.y = rayDir.y;
    raySideDist.y = (rayLoc.y - mapLoc.y) * rayDeltaDist.y;
}
else if(rayDir.y < 0)
{
    rayStepDist.y = -1;
    rayDeltaDist.y = rayStepDist.y / rayDir.y;
    raySideDist.y = (rayLoc.y - mapLoc.y) * rayDeltaDist.y;
}
else
{
    rayStepDist.y = 1;
    rayDeltaDist.y = rayStepDist.y / rayDir.y;
    raySideDist.y = ((mapLoc.y + 1) - rayLoc.y) * rayDeltaDist.y;
}

//Raycasing loop
while(hasCollided == false && tooLong == false)
{
    std::cout << "Raycast - [" << mapLoc.x << " " << mapLoc.y << " " << mapLoc.z << "]\n";

    //side: x = 0, y = 2, z = 1
    if(raySideDist.x < raySideDist.z)
    {
        if(raySideDist.x < raySideDist.y)
        {
            raySideDist.x += rayDeltaDist.x;
            mapLoc.x += rayStepDist.x;
            side = 0;
        }
        else
        {
            raySideDist.y += rayDeltaDist.y;
            mapLoc.y += rayStepDist.y;
            side = 2;
        }
    }
    else
    {
        if(raySideDist.z < raySideDist.y)
        {
            raySideDist.z += rayDeltaDist.z;
            mapLoc.z += rayStepDist.z;
            side = 1;
        }
        else
        {
            raySideDist.y += rayDeltaDist.y;
            mapLoc.y += rayStepDist.y;
            side = 2;
        }
    }

    //If we hit something, exit
    if(world->checkVoxel(mapLoc) == 1)
    {
        hasCollided = true;

    }

    //If the ray's too long, exit
    if(rayIterations > maxIterations)
    {
        tooLong = true;
    }

    //We took a step, so increment the counter
    rayIterations++;
}

//If we actually hit a voxel, place or destroy
if(hasCollided == true)
{
    //Left mouse button - destroy the selected voxel, right mouse button - place a new voxel
    if(event.button.button == SDL_BUTTON_LEFT)
    {
        std::cout << "Destroyer!\n";

        world->deleteVoxel(mapLoc);
    }
    else if(event.button.button == SDL_BUTTON_RIGHT)
    {
        std::cout << "Placer!\n";

        Voxel newvox;

        //Subtract a step based on the last hit side
        if(side == 0)
            mapLoc.x -= rayStepDist.x;
        if(side == 1)
            mapLoc.z -= rayStepDist.z;
        if(side == 2)
            mapLoc.y -= rayStepDist.y;

        newvox.color.r = 1;
        newvox.color.g = 1;
        newvox.color.b = 0;

        //Insert the new voxel
        world->insertVoxel(mapLoc, newvox);
    }
}