walk.love

SX = 800; SY = 500
fov = 360
minz = 0.1

function rotateY(point, angle)
    local rad = angle*math.pi/180
    local cosa = math.cos(rad)
    local sina = math.sin(rad)
    local z = point.z*cosa - point.x*sina
    local x = point.z*sina + point.x*cosa
    return {x=x, y=point.y, z=z}
end

function project(point)
    local factor = fov/point.z
    local x = point.x*factor + SX/2
    local y = -point.y*factor + SY/2
    return {x=x, y=y, z=1}
end

function intersect(v1, v2)
    if v2.z == v1.z then return {x=0, y=0, z=0} end
    xs = (v2.x-v1.x)/(v2.z-v1.z)
    ys = (v2.y-v1.y)/(v2.z-v1.z)
    return {
        x = v1.x+xs*(minz-v1.z),
        y = v1.y+ys*(minz-v1.z),
        z = minz
    }
end

function love.load()
    i = 0
    love.graphics.setMode(SX, SY)
    pos = {x=0, y=-1.6, z=15}
    verticeso = {
        { -5,   0,  0}, { -5,   7,  0}, { 5,   7,  0}, { 5,   0,  0}, -- front wall
        { -5,   0, 10}, { -5,   7, 10}, { 5,   7, 10}, { 5,   0, 10}, --  back wall
        {-10,   0, -5}, {-10,   0, 15}, {10,   0, 15}, {10,   0, -5}, -- ground square
        {-.5,   0,  0}, {-.5, 2.5,  0}, {.5, 2.5,  0}, {.5,   0,  0}, -- door
        { -5, 3.5,  0}, { -5, 3.5, 10}, { 5, 3.5, 10}, { 5, 3.5,  0}  -- first floor
    }
    bones = {
        { 1,  2}, { 2,  3}, { 3,  4}, { 4, 16}, {13, 1}, -- front wall (door)
        { 5,  6}, { 6,  7}, { 7,  8}, { 8,  5},          --  back wall
        { 1,  5}, { 2,  6}, { 3,  7}, { 4,  8},          -- front/back
        { 9, 10}, {10, 11}, {11, 12}, {12,  9},          -- ground square
        {13, 14}, {14, 15}, {15, 16},                    -- door
        {17, 18}, {18, 19}, {19, 20}, {20, 17}           -- first floor
    }
    surfaces = {
        {17, 18, 19, 20}, {1, 2, 6, 5}, {5, 6, 7, 8}, {3, 4, 8, 7},
        {2, 6, 7, 3}, {1, 2, 14, 13}, {14, 15, 3, 2}, {16, 15, 3, 4},
        {9, 10, 11, 12}
    }
    vertices = {}
    plots = {}
    for i = 1, #verticeso do
        v = verticeso[i]
        table.insert(vertices, {
            x = v[1]+pos.x,
            y = v[2]+pos.y,
            z = v[3]+pos.z
        })
        vertices[i] = rotateY(vertices[i], 10)
        table.insert(plots, project(vertices[i]))
    end
    --for k, v in pairs(plots) do print(k, v.x) end
end

function love.update()
    if love.keyboard.isDown("w") then
        for i = 1, #vertices do
            vertices[i].z = vertices[i].z-6*dt
        end
    end
    if love.keyboard.isDown("s") then
        for i = 1, #vertices do
            vertices[i].z = vertices[i].z+6*dt
        end
    end
    if love.keyboard.isDown("a") then
        for i = 1, #vertices do
            vertices[i] = rotateY(vertices[i], 50*dt)
        end
    end
    if love.keyboard.isDown("d") then
        for i = 1, #vertices do
            vertices[i] = rotateY(vertices[i], -50*dt)
        end
    end
    plots = {}
    for i = 1, #vertices do
        table.insert(plots, project(vertices[i]))
    end
end

function love.draw()
    love.graphics.setColor(255, 255, 255, 150)
-- code for bones
--  for i = 1, #bones do
--      b = bones[i]
--      v0 = vertices[b[1]]
--      v1 = vertices[b[2]]
--      if v0.z > minz or v1.z > minz then
--          p0 = plots[b[1]]
--          p1 = plots[b[2]]
--          if v0.z < v1.z then v0, v1, p0, p1 = v1, v0, p1, p0 end
--          if v0.z > minz and v1.z < minz then
--              p1 = project(intersect(v0, v1))
--          end
--          love.graphics.line(p0.x, p0.y, p1.x, p1.y)
--      end
--  end
    for i = 1, #surfaces do
        s = surfaces[i]
        if #s > 2 then --minimum 3 sides
            vs = {}
            visible = false
            cut = false
            for iv = 1, #s do
                table.insert(vs, vertices[s[iv]])
                if vertices[s[iv]].z > minz
                then visible = true
                else cut = true end
            end
            if visible then
                if cut then
                    vsc = {}
                    for iv = 1, #vs do
                        v1 = {x=vs[  iv].x, y=vs[  iv].y, z=vs[  iv].z}
                        if iv == #vs then iv = 0 end
                        v2 = {x=vs[iv+1].x, y=vs[iv+1].y, z=vs[iv+1].z}
                        if v1.z > minz then table.insert(vsc, {x=v1.x, y=v1.y, z=v1.z}) end
                        if v1.z < v2.z then v1, v2 = v2, v1 end
                        if v1.z > minz and v2.z < minz then
                            table.insert(vsc, intersect(v1, v2))
                        end
                    end
                    vs = vsc
                end
                polygon = {}
                for iv = 1, #vs do
                    v = project(vs[iv])
                    table.insert(polygon, v.x)
                    table.insert(polygon, v.y)
                end
                love.graphics.polygon("fill", polygon)
            end
        end
    end
end