Sundog - Devlog - 03
Camera stuff
I hooked up the level boundaries to the camera system. I’ve been using the same camera system for the past couple of years. It works in a fairly straightforward way, and thankfully in pretty game-agnostic, so I’m able to lift it from game to game and it ‘just works’.
This is the guts of it looks like this:
self.old_position = self.position:clone()
self.position = e.position + self.offset
if e.position.x >= self.level_info.bottom_right.x - GAME_WIDTH / 2 then
self.position.x = self.level_info.bottom_right.x - GAME_WIDTH
elseif e.position.x <= self.level_info.top_left.x + GAME_WIDTH / 2 then
self.position.x = self.level_info.top_left.x
end
if e.position.y >= self.level_info.bottom_right.y - GAME_HEIGHT / 2 then
self.position.y = self.level_info.bottom_right.y - GAME_HEIGHT
elseif e.position.y <= self.level_info.top_left.y + GAME_HEIGHT / 2 then
self.position.y = self.level_info.top_left.y
end
self.position.x = lerp(self.old_position.x, self.position.x, self.speed * dt)
self.position.y = lerp(self.old_position.y, self.position.y, self.speed * dt)
love.graphics.translate(-self.position.x, -self.position.y)
Breaking it down
First, we clone the position from last frame, since we’ll use that to smoothly move to new position
self.old_position = self.position:clone()
e is the entity we are tracking.
We apply an offset to it’s position, effectively moving it into the center of the screen.
self.position = e.position + self.offset
We then check the left and right side of the level, and clamp the camera’s x position.
This is so the camera will not move outside of the level boundaries
if e.position.x >= self.level_info.bottom_right.x - GAME_WIDTH / 2 then
self.position.x = self.level_info.bottom_right.x - GAME_WIDTH
elseif e.position.x <= self.level_info.top_left.x + GAME_WIDTH / 2 then
self.position.x = self.level_info.top_left.x
end
We do the same thing for top and bottom of the level
if e.position.y >= self.level_info.bottom_right.y - GAME_HEIGHT / 2 then
self.position.y = self.level_info.bottom_right.y - GAME_HEIGHT
elseif e.position.y <= self.level_info.top_left.y + GAME_HEIGHT / 2 then
self.position.y = self.level_info.top_left.y
end
Now that we have our position calculated, we start moving to it, but we don’t move directly to it, we use a linear interpolation to move the camera somewhat slowly.
self.position.x = lerp(self.old_position.x, self.position.x, self.speed * dt)
self.position.y = lerp(self.old_position.y, self.position.y, self.speed * dt)
Finally, we apply the camera by calling love.graphics.translate
love.graphics.translate(-self.position.x, -self.position.y)