I am trying to animate the ScaleX and ScaleY properties of my Sprite using the following code. Nothing is happening though. I am used to using UIViews and the UIView.Animate method which allows me to set my end result and a duration. Is something like this possible with cocos?
baloon.RunAction(new CCActionTween(.009f, "ScaleX", baloon.ScaleX, (float)(w / baloon.ContentSize.Width)));
baloon.RunAction(new CCActionTween(.009f, "ScaleY", baloon.ScaleY, (float)(h / baloon.ContentSize.Height)));
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So i'm playing around with creating a simple game engine in c++. I needed to render some text so I used this tutorial (http://learnopengl.com/#!In-Practice/Text-Rendering) for guidance. It's using the library freetype 2.
Everything works great, text is rendering as it should. But now when i'm fleshing the ui out and is creating labels I would like to be able to change the size of the text. I can do so by scaling the text, but I would like to be able to do so by using pixels.
Here you can see the scaling in action:
GLfloat xpos = x + ch.Bearing.x * scale;
GLfloat ypos = y + linegap + (font.Characters['H'].Bearing.y - ch.Bearing.y) * scale;
GLfloat w = ch.Size.x * scale;
GLfloat h = ch.Size.y * scale;
So in my method renderText I just pass a scale variable and it scales the text. But I would prefer to use pixels as it is more user friendly, is there any way I could do this in freetype 2 or am I stuck with a scale variable?
Assuming you don't want to regenerate the glyphs at a different resolution, but instead want to specify scale as a unit of pixels instead of a ratio (i.e. you want to say scale = 14 pixels instead of scale = 29%), then you can do the following: Save the height value you passed to FT_Set_Pixel_Sizes (which is 48 in the tutorial). Now if you want a 14-pixel render, just divide 14 by that number (48), so it would be scale = 14.0f / 48.0f. That will give you the scaling needed to render at a 14-pixel scale from a font that was originally generated with a 48-pixel height.
You might want to play with your OpenGL texture filters or mipmapping as well when you do this to improve your results. Additionally, fonts sometimes have low-resolution pixel hinting, which helps them be rendered clearly even at low resolutions; unfortunately this hinting information is lost/not used when you generate a high res texture and then scale it down to a smaller render size, so it might not look as clear as you desire.
I need to scale a sprite's height exactly to a fixed value. I don't think the function scaleBy() or scaleTo() could help. Please help me to figure it out.
Each CCSprite object has properties for the scale, scaleX and scaleY. In your case, you should use the scaleY property and do some simple maths :
sprite.scaleY = DESIRED_HEIGHT/sprite.contentSize.height;
But you have to make sure that your desired height is in float, otherwise you might get some issues, like always having 0 or 1 as a result!
If you want to animate it, you can also use the CCScaleTo action like this :
float scaleY = DESIRED_HEIGHT/sprite.contentSize.height;
[sprite runAction:[CCScaleTo actionWithDuration:duration scaleX:sprite.scaleX scaleY:scaleY]];
Hope this helps!
I've looked around quite a bit and haven't been able to find a concise answer to this question. For my Cocos2D game I have integrated the Chipmunk physics engine. On initialization, I setup the boundaries of the 'playing field' by establishing a series of bodies and static shapes as follows:
- (void)initPlayingField {
// Physics parameters
CGSize fieldSize = _model.fieldSize;
CGFloat radius = 2.0;
CGFloat elasticity = 0.3;
CGFloat friction = 1.0;
// Bottom
CGPoint lowerLeft = ccp(0, 0);
CGPoint lowerRight = ccp(fieldSize.width, 0);
[self addStaticBodyToSpace:lowerLeft finish:lowerRight radius:radius elasticity:elasticity friction:friction];
// Left
CGPoint topLeft = ccp(0, fieldSize.height);
[self addStaticBodyToSpace:lowerLeft finish:topLeft radius:radius elasticity:elasticity friction:friction];
// Right
CGPoint topRight = ccp(fieldSize.width, fieldSize.height);
[self addStaticBodyToSpace:lowerRight finish:topRight radius:radius elasticity:elasticity friction:friction];
// Top
[self addStaticBodyToSpace:topLeft finish:topRight radius:radius elasticity:elasticity friction:friction];
}
This setup works, except for one thing-- the positions of the boundaries appear to be off by a significant amount of pixels to the right. After initializing a player, and sending him towards the boundary walls, it does not bounce off the edges of the screen (as I would expect by setting up the bounding box at 0,0), but rather some number of pixels (maybe 30-50) inwards from the edges of the screen. What gives?
I initially thought the issue came from where I was rendering the player sprite, but after running it through the debugger, everything looks good. Are there special protocols to follow when using chipmunk's positions to render sprites? Do I need to multiply everything by some sort of PIXELS_PER_METER? Would it matter if they are in a sprite sheet? A sprite batch node? Here is how I set the sprite position in my view:
Player *player = [[RootModel sharedModel] player];
self.playerSprite.position = player.position;
self.playerSprite.rotation = player.rotation;
And here is how I set the position in my Model:
- (void)update:(CGFloat)dt {
self.position = self.body->p;
self.rotation = self.body->a;
}
(Yes, I know it's redundant to store the position because chipmunk does that inherently.)
Also, bonus question for for those who finished reading the post. How might you move a body at a constant velocity in whatever direction it is facing, only allowing it to turn left or right at any given time, but never slow down?
What's the shape of the physics body? Perhaps you simply forgot to consider making the shape the same size of the sprite. If you only consider the position, then the sprite will be able to move halfway outside the screen at any border because its position is at the center of the sprite.
To move a body at constant velocity, set its velocity while disabling friction (set to 0?) and allowing it to rebound off of collisions with its impact speed (in Box2D that would be restitution = 1, don't know about Chipmunk).
Have you tried debug drawing the collision shapes? Cocos2D 2.1 has my CCPhysicsDebugNode class in it that makes it pretty easy to add. That will let you know if your geometry is lined up with your graphics. How thick are your boundary shapes? Are you possibly adding the sprites to a parent node that might be offsetting them?
Chipmunk doesn't require you to tune it for any real units. You can just use pixels or whatever.
Lastly, #LearnCocos2D has the right idea about the constant velocity. Set friction to 0 and elasticity to 1.0. You will also probably want to check it's velocity every frame and accelerate it back towards it's normal velocity each frame. Colliding with non-static geometry will cause it to lose speed.
I'm having difficulty getting the Chipmunk physics engine to do what I want. The only solution that appears to work requires some heavy vector math. Before diving into that rabbit hole for the other components of my game, I was hoping someone could fill me in on a better way to go about this. The desired gameplay is as follows:
A character moves around a finite space in a top-down view
Movement is always a constant velocity in whatever direction the character faces
The player taps on the screen, which causes the character to 'turn' towards the touched location
The basic idea is like driving a car. You cannot immediately turn around, but instead must first perform a u-turn. That car must also maintain a constant speed. How might I do this? Bonus question: how can you override whatever method chipmunk calls to update a body's position, and is this a good idea?
There is this tutorial on how to do top down controls using specially configure joints:
http://chipmunk-physics.net/tutorials/ChipmunkTileDemo/
It's based on Chipmunk Pro, but the stuff about controlling the character is easily adapted to vanilla Chipmunk. The "Tank" demo that comes with the non-Pro Chipmunk source implements pretty much the same thing if you want to see some C code for it.
You basically want to rotate the orientation of the player more gradual. You could do this at a constant rate, so when you tap the screen it will start rotating at a constant rate until it has reached the right orientation. This would give a circular turn circle. This will however affect your position, so you would have to keep turning until you would be on a collision course with the position you tapped.
The path you would travel would be similar to that of the game Achtung die kurve.
So you would have to save the location and orientation of the player (x, y and phi coordinates). And to determine whether to stop turning you could do something like this:
dx = playerx - tapx;
dy = playery - tapy;
targetAngle = atan2(dy,dx);
if (phi > targetAngle)
{
if (phi - targetAngle > PI) omega = rotate;
else omega = -rotate;
}
else if (phi < targetAngle)
{
if (targetAngle - phi > PI) omega = -rotate;
else omega = rotate;
}
else omega = 0;
For my project Ogre in c++, I want to create an animation of an object using SimpleSpline of Ogre.
Everything works perfectly, the object is animated along the sequence of points in the path correctly.
Since I need to use a scene with orthographic view, so no perspective, I would still simulate the effect depth "playing" on the scale of the object.
Thus, for each frame updating position and scale of the object in this way:
const Vector3 position = this->getPoint(index_, time_);
const float scale = 1 / (1 + position.z);
node_->setScale(scale, scale, scale);
node_->setPosition(position);
It works quite good. Is there a way to make the depth effect more realistic?
You can try using DeflectorPlane in the script of your particle system.
Here you can find the documentation and the usage.