Merge pull request #4 from mitchwadair/development

Add friction to physics

doc/API/Components/Physics.md

@@ -18,6 +18,8 @@ Physics component handles object physics.
   - [SetStatic](#physicssetstatic)
   - [GetColliderType](#physicsgetcollidertype)
   - [SetColliderType](#physicssetcollidertype)
+  - [GetFriction](#physicsgetfriction)
+  - [SetFriction](#physicssetfriction)
   - [ApplyImpulse](#physicsapplyimpulse)
 
 #Physics
@@ -31,6 +33,7 @@ Physics.bounciness
 Physics.velocity
 Physics.static
 Physics.colliderType
+Physics.friction
 ```
 
 ## Physics:GetMass
@@ -137,14 +140,30 @@ local myCollider = self.gameObject.physics:GetColliderType()
 ```
 
 ## Physics:SetColliderType
-Sets the velocity of the Physics object to the given vector
+Sets the collider type of the Physics object to the value
 ### Arguments
 - `type` - `string` (required) the collider type to set to
 ### Example
 ```lua
 self.gameObject.physics:SetColliderType('CIRCLE')
 ```
 
+## Physics:GetFriction
+Returns the friction coefficient of the object
+### Example
+```lua
+local myFrictionCoefficient = self.gameObject.physics:GetFriction()
+```
+
+## Physics:SetFriction
+Sets the friction coefficient of the Physics object to the given value.  This should be a value between 0 and 1
+### Arguments
+- `type` - `number` (required) the friction coefficient to set to
+### Example
+```lua
+self.gameObject.physics:SetFriction(.5)
+```
+
 ## Physics:ApplyImpulse
 Applies an impulse to the Physics object according to the given vector
 ### Arguments

doc/Tutorials/adding_physics_to_a_gameobject.md

@@ -21,9 +21,11 @@ First, select your game object, and add a new scripted behavior
 ## Setting Values
 The default values for the Physics component are good, but in some cases, you might need to change the values to fit your game object.  Most commonly you'll need to change the collider's width and height, and possibly the collider shape too.
 
-![](https://i.imgur.com/c1xwtvZ.png)
+**NOTE: If you are using a circle collider, the `height` value will not be considered** 
+
+![](https://i.imgur.com/Q4IzV4j.png)
 
 # Visualizing the Collider
-It is not very apparent when adding Physics to your object what your collider will look like.  To visualize it, you can use SFramework's sample box, triangle, and circle sprites.  Just add a child game object and center it on your game object.  Then, add a TextRenderer using the correct collider sprite (make sure the text value is ' '!) and adjust the child object's scale to fit your sprite.  These stretch values are what you will use as the width and height of your Physics component.
+It is not very apparent when adding Physics to your object what your collider will look like.  To visualize it, you can use SFramework's sample box, triangle, and circle sprites.  Just add a child game object and center it on your game object.  Then, add a TextRenderer using the correct collider sprite and adjust the child object's scale to fit your sprite.  These stretch values are what you will use as the width and height of your Physics component.  Make sure you are using a space (' ') as your TextRenderer's text value to display the collider visualizer correctly.
 
 ![](https://i.imgur.com/4DMW0tm.png)

src/SFramework/CS API Extensions/GameObject.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 --[[
     Gets the sprite renderer from the calling GameObject

src/SFramework/Components/MapCollider.lua

@@ -1,3 +1,10 @@
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
+
 function Behavior:Awake()
     local offset = {
         x = self.gameObject.transform:GetPosition().x,

src/SFramework/Components/Physics.lua

@@ -5,8 +5,14 @@ mass number 1
 static boolean False
 bounciness number 0
 colliderType string "BOX"
+friction number 1
 /PublicProperties]]
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 function Behavior:Awake()
     -- initialize physics managaer if it is not present
@@ -25,6 +31,7 @@ function Behavior:Awake()
     if not self.static and self.mass > 0 then self.inverseMass = 1/self.mass end
 
     self.colliderType = string.upper(self.colliderType) --make it more robust
+    self.friction = math.clamp(self.friction, 0, 1) --ensure a value between 0 and 1
 
     self.velocity = Vector3:New(0, 0, 0)
 end
@@ -209,6 +216,30 @@ function Behavior:SetColliderType(type)
     self.colliderType = upperCase
 end
 
+--[[
+    Returns the physics object's friction coefficient
+    
+    @return the friction coefficient of the physics object
+]]--
+function Behavior:GetFriction()
+    return self.friction
+end
+
+--[[
+    Sets the physics object's friction coefficient to the given value
+    
+    @param friction the friction coefficient to set to
+]]--
+function Behavior:SetFriction(friction)
+    if friction == nil then
+        error("missing required argument 'friction' in SetFriction call")
+        return
+    end
+    local f = math.clamp(math.abs(friction), 0, 1)
+
+    self.friction = f
+end
+
 function Behavior:Update()
     local manager = SF.physics.manager
     if not self.static then

src/SFramework/Components/SpriteRenderer.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 function Behavior:Awake()
     --set defaults

src/SFramework/Engines/SF Physics Manager.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 function Behavior:Awake()
     self.physicsObjects = {}
@@ -275,10 +280,14 @@ function Behavior:ResolveCollision(obj1, obj2, data)
     impulseMagnitude = impulseMagnitude / (obj1.physics.inverseMass + obj2.physics.inverseMass)
 
     local impulse = data.normal * impulseMagnitude
-    obj1.physics.velocity = obj1.physics.velocity + (obj1.physics.inverseMass*impulse)
+    local frictionCoeff = obj1.physics.friction * obj2.physics.friction
+    local friction = Vector3:New(data.normal.y * frictionCoeff, data.normal.x * frictionCoeff, 0)/60
+    obj1.physics.velocity = obj1.physics.velocity + (obj1.physics.inverseMass*impulse) - (friction*obj1.physics.inverseMass*Vector3:New(math.sign(obj1.physics.velocity.x), math.sign(obj1.physics.velocity.y), 0))
     if math.abs(obj1.physics.velocity.y) <= .05 * SF.physics.gravity then obj1.physics.velocity.y = 0 end
-    obj2.physics.velocity = obj2.physics.velocity - (obj2.physics.inverseMass*impulse)
+    if math.abs(obj1.physics.velocity.x) <= .02 then obj1.physics.velocity.x = 0 end
+    obj2.physics.velocity = obj2.physics.velocity - (obj2.physics.inverseMass*impulse) + (friction*obj2.physics.inverseMass*Vector3:New(math.sign(obj2.physics.velocity.x), math.sign(obj2.physics.velocity.y), 0))
     if math.abs(obj2.physics.velocity.y) <= .05 * SF.physics.gravity then obj2.physics.velocity.y = 0 end
+    if math.abs(obj2.physics.velocity.x) <= .02 then obj2.physics.velocity.x = 0 end
 
     obj1.transform:SetPosition(obj1.transform:GetPosition() + (data.normal * data.depth))
     obj1.transform:SetPosition(obj1.transform:GetPosition() + Vector3:New(0, .0002, 0))

src/SFramework/LUA Extensions/math.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 --[[
     Returns the sign of the given value

src/SFramework/LUA Extensions/table.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 --[[
     Returns the index of a given object in the given table

src/SFramework/SFramework.lua

@@ -1,4 +1,9 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT
 
 SF = {}
 

src/SFramework/Tables.lua

@@ -1 +1,6 @@
---[[ Made by Mitchell Adair https://github.com/mitchwadair ]]--
+-- Copyright (c) 2020 Mitchell Adair
+-- 
+-- (https://github.com/mitchwadair)
+--  
+-- This software is released under the MIT License.
+-- https://opensource.org/licenses/MIT

src/TestScript.lua

@@ -7,9 +7,10 @@ function Behavior:Awake()
 end
 
 function Behavior:Start()
-    self.gameObject.physics:ApplyImpulse(Vector3:New(-.2, 0, 0))
+    self.gameObject.physics:ApplyImpulse(Vector3:New(0, 0, 0))
 end
 
 function Behavior:Update()
-    --self.gameObject.physics.velocity.x = .1
+    --self.gameObject.physics.velocity.x = -.1
+    --print(self.gameObject.physics.velocity)
 end