Cocos2d does truncate pixels to integers. I subclassed Sprite to modify a few
methods to make it use Floats.:
# Copied from cocos.sprite, and modified to use Float coordinates.
def _create_vertex_list(self):
if self._batch is None:
self._vertex_list = graphics.vertex_list(4,
'v2f/%s' % self._usage,
'c4B', ('t3f', self._texture.tex_coords))
else:
self._vertex_list = self._batch.add(4, GL_QUADS, self._group,
'v2f/%s' % self._usage,
'c4B', ('t3f', self._texture.tex_coords))
self._update_position()
self._update_color()
# Copied from cocos.sprite, and modified to use Float coordinates.
def _update_position(self):
"""updates vertex list"""
if not self._visible:
self._vertex_list.vertices[:] = [0, 0, 0, 0, 0, 0, 0, 0]
return
img = self._texture
if self.transform_anchor_x == self.transform_anchor_y == 0:
if self._rotation:
x1 = -self._image_anchor_x * self._scale
y1 = -self._image_anchor_y * self._scale
x2 = x1 + img.width * self._scale
y2 = y1 + img.height * self._scale
x = self._x
y = self._y
r = -math.radians(self._rotation)
cr = math.cos(r)
sr = math.sin(r)
ax = int(x1 * cr - y1 * sr + x)
ay = int(x1 * sr + y1 * cr + y)
bx = int(x2 * cr - y1 * sr + x)
by = int(x2 * sr + y1 * cr + y)
cx = int(x2 * cr - y2 * sr + x)
cy = int(x2 * sr + y2 * cr + y)
dx = int(x1 * cr - y2 * sr + x)
dy = int(x1 * sr + y2 * cr + y)
self._vertex_list.vertices[:] = [ax, ay, bx, by, cx, cy, dx, dy]
elif self._scale != 1.0:
x1 = int(self._x - self._image_anchor_x * self._scale)
y1 = int(self._y - self._image_anchor_y * self._scale)
x2 = int(x1 + img.width * self._scale)
y2 = int(y1 + img.height * self._scale)
self._vertex_list.vertices[:] = [x1, y1, x2, y1, x2, y2, x1, y2]
else:
x1 = int(self._x - self._image_anchor_x)
y1 = int(self._y - self._image_anchor_y)
x2 = x1 + img.width
y2 = y1 + img.height
self._vertex_list.vertices[:] = [x1, y1, x2, y1, x2, y2, x1, y2]
else:
x1 = - self._image_anchor_x
y1 = - self._image_anchor_y
x2 = x1 + img.width
y2 = y1 + img.height
m = self.get_local_transform()
p1 = m * euclid.Point2(x1, y1)
p2 = m * euclid.Point2(x2, y1)
p3 = m * euclid.Point2(x2, y2)
p4 = m * euclid.Point2(x1, y2)
self._vertex_list.vertices[:] = [
p1.x, p1.y, p2.x, p2.y,
p3.x, p3.y, p4.x, p4.y]
On May 20, 2011, at 2:49 AM, Olof Nilsson wrote:
> I've started using Cocos2d (v0.4.0) recently and encountered the same
> problem as mentioned in the qouted year-old post below. It can be seen
> in the test_tiles.py example, especially if you increase the max
> speed. Basically the scrolling "jitters" when in motion.
>
> Is there a better approach to smooth scrolling, or is this a problem
> with ScrollingManager?
>
> qouted:
> "
> I've noticed in both the 0.3 and svn cocos that scrolling with moving
> sprites sometimes causes weird "vibration" rendering glitches which
> look like a one pixel error interpolation issue or something. If you
> zoom in on the car in the test_tiles while it is scrolling and
> rotated
> you will notice it vibrates.
> I found this issue making a very low resolution game where I was
> trying to use the MoveTo action to move a sprite while focusing on
> that sprite every frame. The sprite would jump back and forth a pixel
> while it was moving in the same direction the scrolling manager was
> scrolling. If I manually moved the sprite with a velocity it would
> have the same problem, but only when the call to set_focus was in the
> layer's scheduled update or some higher level. If i put the
> set_focus
> immediately after the sprite position change in the sprite's
> scheduled
> update method the vibrating would stop for that sprite but other
> moving sprites in the scene would still have the problem.
> Putting the test_tiles scroller.set_focus(car.x, car.y) in a new
> scheduled update in the main scene separate from the car's update
> causes the vibration to occur when moving without rotation as well.
> I've been trying to track down this bug, but I admit not knowing
> where
> to look. I am wondering if inting or rounding floats to pixels
> somewhere is causing the problem but changing the int conversions in
> the scrolling manager back to floats didn't do anything. Or perhaps
> the ordering of update, transform, and draw somewhere is causing
> problems?
> "
>
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