Thursday, November 22, 2012

Square Area....


Square
*click to make bigger*

Definition:

 A Square is a flat shape with 4 equal sides and every angle is a right angle (90°) and opposite sides are parallel.


Diagonals...


A square has two diagonals, they are equal in length and intersect at the middle point.

Diagonal square

The Diagonal is the side length(a) times the square root of 2:
*side length = a = the length between A and D* (see image at top)

Diagonal "d" = a × √2
 

Perimeter...


The Perimeter is 4 times the side length:
Perimeter Square

Perimeter "p" = 4a

Area...


The Area is the side length squared:

Area Square
Area = a2 = a × a

....or half of the diagonal squared:

Area Square 
Area = d2/2


What this looks like in ICE ....



Side length

To work out the side length of the square shown below.....

square side length in softimage ICE

..... Subtract the corner point (-1,-1,0) with corner point (-1,1,0). Then simply get the length of the vector between the them.

side lentgh of a square softimage

 

Perimeter

The light green perimeter value is worked out with the math sum shown below, while the darker green value shows the curve length attribute in ICE, they are both the same.


p = 4.a

calculate perimeter of a square in ICE

Diagonal

The diagonal length as shown by the blue value below was got by....

Daigonal of a square in softimage ICE


d = a .  √2

calculate diagonal of a square in ICE


Area

 Area can be calculated two ways, by multiplying the side lengths or by the diagonal....

Area of a square in ICE

..... here are what those calculations look like in ICE.

Calculate area of a square in ICE


The end :D




Wednesday, November 14, 2012

Underwater fur . . .





First step find reference of animals underwater


Never underestimate the power of reference, here is some I used...

UnderWater Fur
Fur Under the water

Here is some video reference of a tiger underwater.....


.....I also looked at Ink in water.



After watching the reference many times, I decided to break up the "underwater effect" into five different areas....

  1. Force of movement from the object
  2. Wave motion through hair when the object moves
  3.  Water movement and direction
  4.  Other objects making the water move for example the paw of the tiger
  5.  Over all Puff

    Demo Scene

    In my little demo scene for this blog post I'm going to touch on some of the ways I got around these problems. Obviously it includes tons of things I learned from tutorials and other resources. I'm not going to go into to much detail. Honestly I don't know if this is the best way to make under water fur effects, lets just say it worked for me :D Here's a Capture of the demo scene....





    Break down of Scene


    There is an over all modulate by null in this scene - Box null - , so that it looks like the sphere is entering the water, and leaving it again. Also all the effects are in the modeling stack in ICE. None of the effects are in the "Simulation stack".


    Step One: "Force of movement" made with the following ICE Trees

    Create an none simulated ICE tree in the modeling stack. Then get the point velocity from the emitter using the get closest location node, then apply that point velocity value to all the points in the strand. This way we get a strand velocity value for each point on the strand.


    Then I apply the Velocity as a "force", and vary it with the mass of the strands.



    Step two: I made the following ICE trees for the wake.



     The wake was just added to the "force" of the velocity.


    The wake is a simple sin function that takes the global position into account. I added a random around value to the amplitude to get it to be less repetitive.



    Step three: The following ICE Trees are for water direction and movement.


    To start off, watch this tutorial by Paul Smith
    Vector Flow

    So now that you have a feel for vector flow, I used the vector flow of a bunch of curves the represented the "waters" flow direction. This is all still in the modeling stack.




    Here are the curves I made for this scene.... to create variation of motion in the water I just animated the curves to rotate around their local orientation.



    Step Four: Other objects making the water move

    Here I have the strands push away from a Null object. I modified the modulate by null to take into account the strand position of the strands.


    Step Five: Puff


    The puff is just a simple push along the Y axis of the strands to add the illusion of weightlessness.



    Nice thing about doing the "under water effect" in the modelling stack is... I could step through my scene without having to wait for a simulation bar to calculate. And because of the curves I could change the way the water effected the fur on frame 60 but have frame 5 be uneffected. Which is really nice and flexible and feels more like animating then simulating. :D

    Monday, November 12, 2012

    Circle Area


    Circles....

    hula hoop
    Hula Hoop

    The definition of a circle is:
     

    The set of all points on a plane that are a fixed distance from a center.



    Circle terms
    *click too make bigger*
      




    The Radius is the distance from the center to the edge.
    The Diameter starts at one side of the circle, goes through the center and ends on the other side.
    The Circumference is the distance around the edge of the circle.
    The Chord is a line segment whose endpoints lie on the circle. 
    The Tangent is a straight line that touches the circle at a single point.



    When you divide the circumference by the diameter you get 3.141592654...
    which is the irrational number π (Pi) 

    thus :
    Circumference = π × Diameter
    Diameter π × Circumference

    To get the area of a circle you need either the radius or the diameter and π .

    The area of a circle is π times the radius squared, which is written:
    A = π × r2
    Or, in terms of the Diameter :
    A = (π/4) × D2

    A circle has about 80% of the area of a similar-width square.
    The actual value is (π/4) = 0.785398... = 78.5398...%


    Lets look at this in ICE 


    I created a normal circle in Softimage with a radius of 1, and a subdivision count of 16.

    *click too make bigger*
     The ICE attributes on a circle are quite limited, it pretty much only gives you the curve length. So if you want to know say... the area of the circle you will have to work it out for yourself. Here is how I got some of the values I wanted to know.


     π (Pi)

    To get π I used the attribute curvelength (circumference) divided with the diameter (Got the distance between two opposite points on the circle).


    Pi Ice Tree
    *click too make bigger*

    ....you can see from the image below that got me the right value.

    Pi in Softimage ICE
    *click too make bigger*


     Radius

    R = Diameter/2

    Radius Ice Tree
    *click too make bigger* 
    Radius of circle in softimage
    *click too make bigger* 

     

    Area 

    The Blue value is area worked out with diameter and the Green value is area worked out with the radius.
     
    Area ICE tree
    *click too make bigger*
     They both get the same result.....

    Area of a circle in Ice
    *click too make bigger*


    Circumference 

    The Purple value is worked out with the Math in the ICE tree below, where as the green value is the curve length given by the ICE attribute in Softimage.


    Circumference Ice Tree
    *click too make bigger*
     They are both the same...

    Circumference of a circle with Ice
    *click too make bigger*


    Diameter

    Calculating Diameter using the math sum :
    D = r . 2

    Diameter Ice Tree
    *click too make bigger*

    Diameter of a circle in ICE
    *click too make bigger*

    Unit Circle


     .....this is a really fun way tho see how a circle is a set of points that are a fixed distance from a center.