Weird flickering with constantly moving sprites

SDK Bug Reports
1

I'm not even sure if this is an SDK bug, but I have encountered a crazy weird bug when moving sprites every frame. I didn't have a device so I sent a build in the dev discord for testing, and they found an issue that the simulator doesn't even show. When moving sprites every frame (to an already floored position) The objects flicker, especially noticable on 50% opacity parts. I have attached a build and some relevant source code parts. This also isn't a device issue, since I got the exact same responce from 2 people.

table.insert(fishies, Fish(-26, -14, 0))
sprite_rock = Obj(64, 0, -50, image_rock)
sprite_seaweed1 = Obj(-5, 0, 26, image_seaweed1)
sprite_seaweed2 = Obj(-14, 0, -26, image_seaweed2)

gfx.sprite.setBackgroundDrawingCallback(
        function( x, y, width, height )
            image_bg:draw(0, 0)
        end
    )

function pd.update()
    dt = playdate.getElapsedTime()
    playdate.resetElapsedTime()

    gfx.sprite.update()

    -- cam rotation
    cam_yaw = cam_yaw%360
    if pd.isCrankDocked() then
        cam_yaw += 0.125
    else
        cam_yaw += math.floor(pd.getCrankChange()/2)
    end
end


function rotate_around_center(x, y, center_x, center_y, angle)
    local translated_x = x - center_x
    local translated_y = y - center_y

    local rad = math.rad(angle)
    local cos_angle = math.cos(rad)
    local sin_angle = math.sin(rad)
    local rotated_x = translated_x * cos_angle - translated_y * sin_angle
    local rotated_y = translated_x * sin_angle + translated_y * cos_angle

    local final_x = rotated_x + center_x
    local final_y = rotated_y*cam_pitch_multiplier + center_y
    return final_x, final_y
end

function Obj:update()
    Obj.super.update(self)
    local screen_center_x, screen_center_y = 200, 170
    local new_x, new_y = rotate_around_center(self.cur_x+200, self.cur_y-self.cur_z+120, screen_center_x, screen_center_y, cam_yaw)
    self:moveTo(math.floor(new_x), math.floor(new_y))
    self:setZIndex(math.floor(new_y))
end

function Fish:update()
    Fish.super.update(self)
    local screen_center_x, screen_center_y = 200, 170
    local new_x, new_y = rotate_around_center(self.cur_x, self.cur_y-self.cur_z, 0, 0, cam_yaw)
    self:moveTo(math.floor(new_x + screen_center_x), math.floor(new_y + screen_center_y))
    self:setZIndex(math.floor(new_y+screen_center_y))

    -- following targets
    if self.wait_time > 0 then
        self.wait_time -= dt
    else
        self.cur_x, self.cur_y, self.cur_z = move_towards(self.cur_x, self.cur_y, self.cur_z, self.target_x, self.target_y, self.target_z, self.speed)
        if distance_between(self.cur_x, self.cur_y, self.target_x, self.target_y) < 2 then
            self:new_target()
            self.wait_time = math.random(10, 50) / 10
        end
    end
end

current build:
fishbowl.pdx.zip (61.8 KB)
Sadly I'm not allowed to upload videos, and a gif couldn't show my issue.

2

Are you talking about dither flashing or is it a z-index problem?

3

Well dither flashing is a lot more subtle, while the video I got was a lot different. This might be an issue with Z-sorting, but I'm not sure how that could cause this. I can only attach the video in a zip because of the site, but here it is:
video.zip (5.7 MB)

4

I did remove the dither-flashing, and while it still does the same thing now, it's a lot more subtle. I guess I can count this as solved.

1 Like