Develop Reference

How can i make a rigidbody speed up everytime it collides with a wall at an angle?

I am trying to make a game where i got a ball with an arrow rotating around it. The ball starts as immovable, but when i hit a button i launch it to the direction the arrow is pointing at. Player will have the option mid air to press another button to make the ball "sticky" so when it hits a wall it will stick to the surface and repeat the process till he gets to the top of the level.
Aside from that, i want to give the option to the player to not stick to the wall if he doesn't press that button and instead bounce off the wall but when he does that, the player should speed up with every bounce, giving the option to either play it safe and slow or try to go fast getting more points as he does.
For the early prototyping i used force to move the player up every time he launches but i am not sure how i can make him speed up every time he bounces off the wall. It feels to me like a math problem more than it is a coding challenge. What i am thinking is that i have to find the angle on which player hits the wall, and add force according to that towards the direction he is supposed to follow after the collision.
Sadly i am not that good with trigonometry (working on it though). I am thinking that i might need to use a formula containing sin, cos, tan formulas but i m not sure how to do it. Any help is much appriciated! If you need more information on it please tell me and i ll be happy to provide.
Edit: After the first reply to this question i also found out those links that dive deeper into the subject. I m gona link them here for people that have the same issue.
Bouncing a ball off a wall with arbitrary angle?
http://www.3dkingdoms.com/weekly/weekly.php?a=2

If your ball has velocity vector V=(vx,vy), then after bouncing from standing surface with normal N, ball's new velocity is
V' = V - 2 * N * (V.dot.N)
where dot is scalar product of vectors (vx*nx+vy*ny)
Particular cases:
bouncing from vertical wall (N=(+-1, 0)) causes reversing of vx-component, vy component remains the same. V' = (-vx, vy)
bouncing from horizontal wall (N=(0, +-1)) causes reversing of vy-component, vx component remains the same. V' = (vx, -vy)
Note I recommend to work in velocity vector components, and use angles only when they are really needed.
If you need to calculate bouncing from moving bat, it is worth to change stationary coordinate system to moving one, connected with the bat, find reflection in that system, and revert to stationary system.

Ok so problem was solved!
I want to thank both #MBo and #shingo for their contribution to the solution. While the answer of Mbo solved the problem via trigonometry and gave me nice material to study and figure out how things work, i followed shingo's advice in the comments of my question and managed to do it without diving deep into math.
So basically what he said, and what i did, was to use Unity's physics engine and let the ball hit the wall. After the ball bounces off the wall, it gets a new Velocity vector towards the direction it would go based on physics. I then created an OnColllisionExit check, and when the ball stops colliding with the wall, i AddForce to it to the direction of its new Velocity Vector3.
Works like a charm!
Thank you all for your contributions!

How do you reduce the drag experienced when jumping in unity?

I've created a player character in Unity and jumping works like it should.
But when she starts to fall back down to the ground, I want her to fall quickly.
She is almost floating back down, which interrupts the level's feel.
What parameter am I missing that allows her to fall back to the ground?
I'm going for a Mario feel, where he crests at the jump and then falls fairly quickly back down to the ground.

Simply add more gravity to whatever component that controls your characters' physics e.g. If you are using a rigidbody component then increase the gravity property.

Unity 2D - Freeze axis and AddForceAtPosition

I'm learning Unity 2D and I want to do something like this:
Basically the character runs into the box/edge and it falls over. BUT! I want to lock down the X axis somehow. So in reality it would kinda look like if it was just rotated simple by 90 degrees (with some kind of acceleration).
I've tried to do it with rigidbody2d and edgecollider and AddForceAtPosition, but I failed miserably.
What I really wanted to do is lock down the "wall" and apply the force at the very top of the rigidbody so it would just fall over to the right, but it simply didn't work out.
Any help would be appreciated!

Remember that same logic applies to physics in games as it does to physics in real life. Just make a hinge and put the anchor and connected anchor at the same location at the bottom and set a limit for hinge.
Wall:
Hinge:
I set Lower Angle to something near 90, otherwise wall becomes uneven when it drops.
Remember to put a Rigidbody2D and a Box Collider for wall.

Firstly, I would lock the rotational axes that you don't want to move on your rigidbody, then, if your object origin is located on the ground / bottom of the object, you can add rotational torque to the object to achieve the affect you want :) http://docs.unity3d.com/ScriptReference/Rigidbody.AddTorque.html

Character slowly move up the ground using a humanoid animation type in Unity

I have a marine model used in my start project, which will uncontrollably lift off the ground when running. I import the fbx resources, set the animation type as humanoid and configured the avatar by automatically mapping, set up a animator controller that contains only a running animation. Here is about several seconds after playing:
But when using a generic animation type everything works fine. Any suggestions to fix this while still using the avatar system?
UPDATE：
Configure of my 3D model:

This is obviously caused by root motion. What happens is, one loop of your animation takes the character slightly higher. Adding these slight changes up, you get what you're getting. If you don't need root motion (doesn't look like you do), disable it (from the animator component's settings). If you do, either edit the animation to make sure it fits, or disable root motion along the Y-axis (you can do this from the animation's import settings).
In case you don't know what root motion is, it's when the root bone of your model has animations applied. You obviously can't create the entire animation of character running up and down your levels, and until recently (though not MUCH recently) characters where animated in-place, and moved procedurally via code (I know for a fact that Unreal Tournament 3 uses this method, as would any UDK user). Then, people started wondering how they could make their characters move more realistically? I mean, it's not like you walk forward at a constant rate of 4 km/h, you tend to slow down and speed up during different parts of the walk cycle. The same can be applied to video game characters using the technique known as root motion.
With root motion, you actually move the character forward during its animations. This will cause an animation to look really bad in max or maya, since the character will just snap back to its original place after a loop. However, this data is used intelligently in game engines: Rather than use the absolute position the animation yields, you take the velocity out of it between each two frames, and move your character based on that velocity (Unreal engine actually has a really neat acceleration mode for applying root motion, though I'm not really sure how that would be different from velocity mode). This will make your character move forward at the same rate the animation does, and thus you can actually animate the character's movement as well as its limbs and joints. Moreover, since you're using the velocity and not position data from the animation, it will look exactly as you'd expect it to. If you're interested in this technique, take a look at the Mechanim demo pack they have on the asset store. It makes extensive use of root motion to move the character around.

My company was having a similar issue but we still wanted to keep the "Apply Root Motion" toggle checked. When the same animation played on loop, the model stayed in place but if several different animations were played one after another, this caused the model to rotate / shift in position.
The solution for us was ticking these check boxes in the animation settings for each animation. Root Transform Rotation, Root Transform Position (Y), Root Transform Position (XZ).

I had the same issue a few days ago. I found out that the problem was the Apply Root Motion in the Animator script. Make sure it's unchecked.

Tag your player with "Player" in scene
and use this script
float y;
GameObject player;
void Start ()
{
player = GameObject.FindGameObjectWithTag("Player");
y = player.transform.position.y;
}
// Update is called once per frame
void Update ()
{
float diff = player.transform.position.y;
player.transform.Translate ( 0, 0,z - diff);
y = player.transform.position.y;
}
it is little hacky soultion but works!!
note: if you want to use y movement at some point just calculate and add it to diff variable.

For those who couldn't solve this issue with 'bake into pose'.
I tried 'Bake into Pose-Y', but it didn't work.
Meanwhile, in FBX > Animation > Motion, I set 'Root Motion Node' as 'Root Transform'(It was 'None' before), it solved my problem. Unity version is 2020.3.34f1.

Hiding objects that obscure the player in a 3D scene

I'm designing a 3D game with a camera not entirely unlike that in The Sims and I want to prevent the player character from being hidden behind objects, including walls, pillars and other objects.
One easy way to handle the walls case is to have them face inwards and not have an other side, but that won't cover the other cases at all.
What I had planned is to somehow check for objects that are "in front" of the player, relative to the camera, and hide them - be it by alpha blending or not rendering at all.
One probably not so good idea I had in mind is to scan from the camera to the player in a straight line and see if you hit a non-hidden object, continuing until you reach the player. Unfortunately, I am an almost complete newbie on 3D programming.
Demonstration SVG illustration < that wall panel obscures the player, so it must be hidden. Another unrelated and pretty much already solved problem is removing all three wall panels on that side, which is irrelevant to this question and only caused by the mapping system I came up with.

What I had planned is to somehow check for objects that are "in front" of the player, relative to the camera, and hide them - be it by alpha blending or not rendering at all.
This is a good plan. You'll want to incorporate some kind of bounding volume onto the player, so the entire player (plus a little extra) is visible at all times. Then, simply run the intersection algorithm for each corner of the bounding volume.

Finding which object is at a given point on screen is called picking. Here's an XNA link for you which should direct you to an example. The idea is that you retrieve the 3D point in the game from the 2D point, and then can use standard collision detection methods to work out which object is occupying that space. Then you can elect to render that object differently.
One hack which might suffice if you have trouble with the picking approach is to render the character once as part of the scene, and then render it again at the end at half-alpha on top of everything. That way you can see the whole character and the wall, though you won't see through the wall as such.

One easy way, at least for prototyping, would be to always draw the player after you draw the rest of the scene. This would ensure that the player is rendered on top of anything else in the scene. Crude but effective.

Create a bounding volume from the camera to the extents of the player, determine what objects intersect that volume, and then render them in whatever alternate style you want?
There might be some ultra-clever way to do this, but this seems like the pretty straightforward version, and shouldn't be too much of a perf hit (you're probably doing collision every frame anyway....)

The simplest thing I can think of that should work relatively well is to model all obstacles by a plane perpendicular to your ground (assuming you have a ground.) Roughly assuming everything that is an obstacle is a wall with some height.
Model your player as a point somewhere, and model your camera as another point. The line in 3d that connects these two points lies in a plane that is particularly interesting to you, because if this plane intersects an "obstacle plane" below the height of the obstacle, that means that that obstacle is blocking your view of the player point.
I hope thats somewhat clear. To make this into an algorithm you'd have to implement a general method for determining where two planes intersect (to determine if the obstacle is tall enough to block view.)