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Search the Community: Showing results for tags 'math'.
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Hello Everyone, http://www.hossamfx.org/mathinhoudinivol2/ Hello Everyone, Description: In volume two of Math in Houdini training. We will continue exploring the big role of math in creating visual effects and controlling the simulation behavior and this time we will move to more advanced concepts and provide cool projects. I will explain one of most important physical parameter: the gradient. And show you how to use it in rigging and collision and give you wide idea about using gradient in different operations in Houdini also We will go indepth with matrices and learn cool techniques using the matrix: it is the “Frame of Reference” you must know this magic secret about matrix. If you have many questions about Quaternion parameter, So we will dive into this concept and answer all questions with cool projects and we will see how to create quaternion field to effectparticles motion and if you don’t know what is the Vector 4, we will have cool project about using vector 4 inside the wire solver dynamics. And I will show you how it to build your own cloth simulation from scratch, this part will give wide idea about how the dynamic solvers work and what is the constraint , gravity , and how the collision is calculated ….. and many other math topics. Thank you. Lesson plan WHAT IS THE GRADIENT, AND FOR WHAT !!! all dynamic solvers use Gradient and normal and velocity and collision calculations, all this Physical Parameters use Gradient, you absolutely Know what is the Gradient !!! ? 1. Gradient & Slope Relationship– Are there any relationship between it? 2. It can create Normal – slope can create normal, how? 3. Speed and Velocity calculates –it is awesome how slope can calculates speed for everything. 4. Slope & Dot product in Rigging – No more tutorials about how to Rig the wheel. 5. Gradient of surface – Slope can create Gradient 2D field. MATRIX IN DEPTH !!! we will start by talking about for what we need matrix and next it will be more clear how it is easy to use matrix, and Frame of Reference is strong concept that you must have idea on how to use. 6. Why we created the Matrices – to understand matrices I must know for what it was created. 7. Recreating the Matrix – Now we will see how it is more easy with Matrices. 8. Frame of Reference – it is cool Concept you must know how to use with matrices. QUATERNION, NO MORE QUESTIONS ??? you don't know any thing about quaternion! you will know every thing about it, for what, when to use, how to control and how to build field of quaternion to advect particles. 9. What is the Quaternion – You will Have depth understand of this Scary parameter. 10. Quaternion Field part 1 – Quaternion inside Dynamics can create awesome animation in Particles. 11. Quaternion Field part 2 –How to Keep Particles inside defiened Volume using quaternion attribut VECTOR 4 IS A QUATERNION, ... !!! the orient attribute in the Wire solver is very important and you must know how it work, in this project we will manipulate this Attribute to create procedural dynamic animation. 12. Quaternion & Wire Solver – Big role of Quaternion in wire object. 13. Feelers & Quaternion part 1 –Feelers of insects moving around all the time, we will simulate this motion with quaternion. 14. Feelers & Quaternion part 2 –How to control the physical parameters of feelers to get nice real motion. SIMULATION CODE & COLLISION it is very important to get depth understand of how the Dynamic solvers work, we will see how we can build cloth simulation and add collision to this simulation using the Point VOP and Sop Solver. 15. Apply Gravity –Without any dynamics solvers, we will create our solver and start by adding gravity force to objects using the point vop and sop solver. 16. Create Cloth Force – Define the force spring between cloth object points and create pin constraint for new solver. 17. Gradient & Collision –Gradient of Volume is the way to create collision between objects. ِAll Content With Project Files . Full information Here
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Hi I want to randomly select two points from a geo input in a VEX wrangle, so far I have this: int _selectedPts[]; _selectedPts[0] = rand(@numpt); _selectedPts[1] = rand(@numpt); setattrib(geoself(),"point", "Cd", _selectedPts[0], 0, {1,0,0}, "set"); setattrib(geoself(),"point", "Cd", _selectedPts[1], 0, {1,0,0}, "set"); I searched on the VEX docs but every random function I found could only return float numbers, but I need integer numbers. How can I solve this?

Hi I need an array wich stores a range of numbers, starting at zero and ending at @numpt (total amount of points in a geometry). Is there a fast way to do this apart from filling the array in a for loop? Thanks

Hi ladies and gentlemen, boys and girls, I have a job to create a kaleidoscope animation. I'm just learning how a Kaleidoscope works in real life and time is limited. Has anyone ever worked on such a project and can give tips on how to get started and maybe some math behind how it works? I've attached a video I found that has this effect created by buck (starting at about 16 seconds in). Any help here would be much appreciated really. Thanks in advance. Sherwin Williams  KaleidoscopeSD.mp4

 kaleidoscope
 symmetry
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Hi EVERYONE : Maybe this tutorial is not very short, watch it completely, i am sure that you find new stuff about matrix and you will learn new technique .Hope you find it useful !!! Hossam Aldin Alaliwi more training here : www.hossamfx.org

if you have some problems with matrix, how it work, how to use , HOPE this tutorial will help .Hossam Aldin Alaliwi full tutorial here : hossamfx.org/mathinhoudinivol2/ cheers!

Hello, I'm trying to replicate the same deformation as seen in the gif below. After some research I believe it's got something to do with Spherical Coordinates? I implemented the formula from this site which is: radius = sqrt(x^2 + y^2 + z^2) polar = arccos(z/radius) azimuthal = atan2(y, x) x = radius * sin(polar) * cos(azimuthal) y = radius * sin(polar) * sin(azimuthal) z = radius * cos(polar) But this results in some pinching of the cube at both poles, so maybe this isn't right, or I haven't done it correctly? Has any one got any experience with something like this? Any help would be really appreciated. Thank you sphere_deform.hip

Hello community : i created this short tutorial on how to use the reorient attribute node in houdini and also i showed how it is work, it is some math matrix stuff, hope you find it helpful and hope you like it : Note : this training will give you nice idea of using the Matrix in Houdini , .

If I want to transform a velocity vector by a matrix4, do I just multiply it by the transpose(inverse(matrix4))? maybe I need to extract the scale from the matrix and multiply the velocity by that as well? Cross posting from https://www.sidefx.com/forum/topic/45863/ in case more people will see it here

http://www.hossamfx.org/mathinhoudini/ Description: This training demonstrates the big role of Math in creating visual effects and controlling the simulation behavior in Houdini FX animation software. I will cover many of the most popular math topics in computer graphics and I will show you how to apply these concepts inside Houdini with some cool projects. I will focus on what we need to know from math for using in VFX without diving into complex mathematical details as this training is not about pure math. I will show you how the Dot product can be used with the Flip Fluid, and how to create windy curves using the Cross product, and how the Matrices can determine the velocity and store the rotation data.....and many other features of using Math in Houdini. Lesson plan 1. Introduction to vectors – What is the vectors and, why we need it in math and physic and CG ?. 2. Dot product definition – Introduction to Dot product equation in math: input, return, formula, spatial situation, deficiency of Dot product . 3. Dot product and angle calculate – Simple example in Houdini for using Dot product to calculate angle between two geometry. 4. Dot product inside flip fluid 01 – Create custom force attribute for controlling fluid behavior. 5. Dot product inside flip fluid 02 – Solving deficiency in Dot product and final behavior test. 6. Cross Product definition – Introduction to Cross product equation: what we need to know about Cross Product for using in CG, and what we don't need ?. 7. Cross Product and particles 01 – Aiming dynamic force in particles by Cross product for creating windy curves (like frozen animation film). 8. Cross Product and particles 02 – Adding randomizing vector to Cross product and update vector every 10 frames. 9. Cross Product and particles 03 – Add amplitude to Cross Product direction vector and final simulation. 10. Cross Product and particles 04 – Reorient all curves by one direction using For each SOP. 11. Cross Product and particles 05 – Emitting particles from curves and creating advanced time manipulating expressions with time shift node . 12. Matrix 01 – Rotate the attributes by Matrix to save the orientation after rotation. 13. Matrix 02 – Generate Matrix using Align Vex Node and create attributes to store reorientation Matrix in, Create advanced reorient system using Matrices and For Each. 14. Matrix 03 – Without Matrix it will need a code of 20 lines to do this effect, Modify particles velocity vector by rotation matrix. 15. Sine Function 01 – What is the sine function parts in math. 16. Sine Function 02 – Adding two sine wave to simple grid. 17. Decay Solver 01 – What is the decay and what are the types of decay in life. 18. Decay Solver 02 – Creating decay solver simulation in Houdini to decay physical attributes like fluid's temperature, viscosity and cloth's wetness….etc. 19. Manipulate Rang[01] – Creating 10 different complex shapes from simple point number expression. ِAll Content With Project Files .

I recently came across Zach's awesome work and saw this piece. Started hunting down how to achieve such an effect and found circle tangent chains is what they are called. I couldn't find out how to actually make one though? Does anyone know where I can find more info or how to do this? I was also thinking the bullet solver maybe good for this? Any ideas greatly appreciated

Hi, This is something I really don't understand and I didn't find anything in the Houdini help. Can anyone explain it in simple terms? Is it only useful in shading? Thanks

hello everyone: more info here : http://www.hossamfx.org/mathinhoudini/ This training demonstrates the big role of Math in creating visual effects and controlling the simulation behavior in Houdini FX animation software. I will cover many of the most popular math topics in computer graphics and I will show you how to apply these concepts inside Houdini with some cool projects. I will focus on what we need to know from math for using in VFX without diving into complex mathematical details as this training is not about pure math. I will show you how the Dot product can be used with the Flip Fluid, and how to create windy curves using the Cross product, and how the Matrices can determine the velocity and store the rotation data.....and many other features of using Math in Houdini.

Hey Guys! I've been experimenting with the refract node in vopsop context as well as the refract() function in vex. I'm curious if anyone has been able to break that node down to it's raw form? I would essentially like to know how it actually evaluates it's inputs. Can anyone shed some light on that? I would like to know the math behind it. The refract function takes three inputs, a direction vector, a normalized normal and an index of refraction. thanks!

I am still working on this research project, and I am running up against a few rather serious blocks trying to derive the information from the simulation to input into the functions I have developed. The goal of the project is to make a traffic simulator that can be used as a drop in for even complicated city scenes with minimal input required from an artist. I currently have 2 functions, one for the particle velocity and one for the turn velocity in the intersections. I will break down each, hopefully someone will be able to help me figure out how to generate my needed attributes. Velocity: Simple enough, x is the only variable I care about here. It refers to the distance between a given particle and the next nearest. This one is designed to allow for automatic adjustments in velocity so the "cars" don't collide. As the cars get close together, the whole thing aproaches 0, farther away it goes to 1 and moves smoothly between the two. I will be multiplying this by a scalar and direction vector to give an actual velocity vector. I have already figured out the parameters for it using some math modeling software, but in houdini I am struggling with calculating the next nearest particle. I know I can use the distance VOP to get the actual variable, but for that I need the nearest particle value. Rotation: This is intended to go in the Turn POP. For this one I need to get two variables, but only on collision with one of my intersection boxes. v is the velocity that the particle has at collision. s is the distance from the colision point to a reference point on each intersection. The calculation will (should) give the correct deg/sec to calculate correct turn rate to move in a perfect quarter circle with a turn radius of s. Also, I need a way to switch between these, meaning out of intersections the speed varying function takes effect, in intersections the speed is held constant and the turn node takes effect, turning the particle through the intersection. I am planning on using the collision POP's numhit value with a mod2 so it alternates between 0 and 1 for even and odd hits. since each intersection will produce 2 hits, it should work out perfectly. unfortunately I cannot seem to figure out how to use numhit or any other attribute in a switch node. city streets basic.hipnc