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local boundary = {
x = 200,
y = 100,
w = 100,
h = 80,
}
local bg = {
x = 200,
y = 100,
w = 300,
h = 200
}
local p = {
x = boundary.x + 10,
y = boundary.y + 10,
speed = 100,
}
function jin.core.onLoad()
end
local function clamp(x, a, b)
return math.min(math.max(x, a), b)
end
function jin.core.onEvent(e)
if e.type == "Quit" then
jin.core.stop()
end
if e.type == "KeyDown" then
if e.key == "Escape" then
jin.core.stop()
end
if e.key == "Left" then
p.x = p.x - p.speed
elseif e.key == "Right" then
p.x = p.x + p.speed
elseif e.key == "Up" then
p.y = p.y - p.speed
elseif e.key == "Down" then
p.y = p.y + p.speed
end
p.x = clamp(p.x, boundary.x, boundary.x + boundary.w)
p.y = clamp(p.y, boundary.y, boundary.y + boundary.h)
end
end
local function updateBg()
local x0 = boundary.x
local x1 = boundary.x + boundary.w
local tx = (p.x - x0) / (x1 - x0)
bg.x = tx * (x1 - x0 - bg.w) + x0
local y0 = boundary.y
local y1 = boundary.y + boundary.h
local ty = (p.y - y0) / (y1 - y0)
bg.y = ty * (y1 - y0 - bg.h) + y0
end
function jin.core.onUpdate(dt)
updateBg()
end
function jin.core.onDraw()
jin.graphics.setColor(100, 100, 100, 255)
jin.graphics.rect("fill", bg.x, bg.y, bg.w, bg.h)
jin.graphics.setColor(255,255,255,255)
jin.graphics.rect("line", boundary.x, boundary.y, boundary.w, boundary.h)
jin.graphics.setColor(255,0,0,255)
jin.graphics.rect("fill", p.x, p.y, 3, 3)
end
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