Dodger3D

local tx,ty = term.getSize()

local function createWorld()
    local world = {
        sprites = {},
        camera = {},
        getDistance = function(x1, y1, z1, x2, y2, z2)
            local mn = {x1, y1, z1}
            local mx = {x2, y2, z2}
            --[[for i=1,#mn do
                if mn[i] > mx[i] then
                    local temp = mx[i]
                    mx[i] = mn[i]
                    mn[i] = temp
                end
            end]]

            local dif = {mx[1]-mn[1], mx[2]-mn[2], mx[3]-mn[3]}
            local dist = (dif[1]+dif[2]+dif[3])/2
            return {dist, dif}
        end,
        addSprite = function(self, sprite)
            local sprites = self.sprites
            if sprites == nil then sprites = {} end
            sprites[#sprites + 1] = sprite
            self.sprites = sprites
        end,
        checkAll = function(self, s)
            if self.sprites ~= nil then
                for i=1,#self.sprites do
                    if check(s, self.sprites[i]) then return true end
                end
            end
            return false
        end,
        check = function(s1, s2)
            for x=s1.x,s1.x+s1.width do
                for y=s1.y,s1.y+s1.height do
                    for z=s1.z,s1.z+s1.depth do

                        for x2=s2.x,s2.x+s2.width do
                            for y2=s2.y,s2.y+s2.height do
                                for z2=s2.z,s2.z+s2.depth do
                                    if x == x2 and y == y2 and z == z2 then return true end
                                end
                            end
                        end
                    end
                end
            end
            return false
        end,
        draw = function(self)

            if self.sprites ~= nil and self.camera ~= nil then
                for i=1,#self.sprites do
                    local sprite = self.sprites[i]
                    self:drawSprite(sprite.x,
                                    sprite.y,
                                    sprite.z,
                                    sprite.width,
                                    sprite.height,
                                    sprite.depth,
                                    sprite.char,
                                    sprite.cols,
                                    self.getDistance(self.camera[4][1], self.camera[4][2], self.camera[4][3], sprite.x, sprite.y, sprite.z))
                end
            end
        end,
        convertDifference = function(dir, dims)
            local ndif = {0,0,0}
            for i=1,dims do
                if dir[i] < 0 then ndif[i] = -1
                elseif dir[i] > 0 then ndif[i] = 1 end
            end
            return ndif
        end,
        checkViewpoint = function(self, dir, dif, dims)
            dif = self.convertDifference(dir, dims)
            for i=1,dims do
                if dir[i] ~= dif[i] then return false end
            end
            return true
        end,
        drawSprite = function(self, x, y, z, width, height, depth, char, cols, dist)
            local scale = (dist[2][3]/2)
            --local scale = dist[1]
            local todo = 1
            if scale < 0 then todo = -1 end
            local scale = math.floor(scale + 0.5)
            if self:checkViewpoint(self.camera, dist[2], 3) then
                --for sz=z,depth do
                    local from = {x+self.camera[4][1],y+self.camera[4][2]}
                    local to = {x+width+self.camera[4][1],y+height+self.camera[4][2]}
                    local ft = true
                    for i=1,scale do
                        if ft == true then
                            from[1] = from[1] - todo
                            from[2] = from[2] - todo
                            ft = false
                        else
                            to[1] = to[1] + todo
                            to[2] = to[2] + todo
                            ft = true
                        end
                    end

                    for sx=from[1],to[1] do
                        for sy=from[2],to[2] do
                            if sx > 0 and sx <= tx and sy > 0 and sy <= ty then
                                term.setCursorPos(sx, sy)
                                term.setBackgroundColor(cols[1])
                                term.setTextColor(cols[2])
                                term.write(char)
                            end
                        end
                    end
                    --scale = scale + 0.1
                --end
            end
        end,
    }
    return world
end

local function createSprite(sworld, sx, sy, sz, swidth, sheight, sdepth, sback_col, stext_col, schar)
    local sprite = {
        x = sx,
        y = sy,
        z = sz,
        width = swidth,
        height = sheight,
        depth = sdepth,
        cols = {sback_col, stext_col},
        char = schar,
        children = {},
        world = sworld,
        moveChildren = function(self, dx, dy, dz, clever)
            if children ~= nil then
                for i=1,#self.children do self.children[i]:move(dx, dy, dz, clever) end
            end
        end,
        move = function(self, dx, dy, dz, clever)
            local old = {self.x, self.y, self.z}
            self.x = self.x + dx
            self.y = self.y + dy
            self.z = self.z + sz
            if clever then
                if self.world:checkAll(self) then
                    self.x = old[1]
                    self.y = old[2]
                    self.z = old[3]
                    return false
                end
            end
            moveChildren(dx, dy, dz, clever)
            return true
        end,
    }
    return sprite
end

local function clear()
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.black)
    term.clear()
    term.setCursorPos(1,1)
end

--sprite function:
--world, x, y, z, width, height, depth, background_colour, text_colour, character
local world = createWorld()
local block = createSprite(world, 3, 3, 1, 1, 1, 1, colors.red, colors.green, "#")
local b2 = createSprite(world, 17, 13, 1, 1, 1, 1, colors.blue, colors.yellow, "#")

world.camera = {1, 1, 1, {0,0,0}}
world:addSprite(block)
world:addSprite(b2)

term.clear()
term.setCursorPos(1,1)
world:draw()

local on = true
local interval = 0.2

local timer = os.startTimer(0)

local function moveC(dx, dy, dz)
    world.camera[4][1] = world.camera[4][1] + dx
    world.camera[4][2] = world.camera[4][2] + dy
    world.camera[4][3] = world.camera[4][3] + dz
end

while on do
    local event, p1 = os.pullEvent()
    if event == "timer" and p1 == timer then
        clear()
        world:draw()
        timer = os.startTimer(interval)
    elseif event == "key" then
        local key = p1
        if key == 29 then
            on = false
        elseif key == 200 then --up
            moveC(0, 0, 1)
        elseif key == 203 then --left
            moveC(-1, 0, 0)
        elseif key == 208 then --down
            moveC(0, 0, -1)
        elseif key == 205 then --right
            moveC(1, 0, 0)
        end
    end
end