# Entropy

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27

3 Neutral

• Rank
Peon

## Personal Information

• Name
Ioannis Kalias
1. ## Suggestive contours - Apparent Ridges

Apparent Ridges for Line Drawing another approach for line drawing maybe more easy to implement http://people.csail.mit.edu/tjudd/apparentLines.pdf
2. ## Suggestive contours - Apparent Ridges

Hi there can anybody help with the suggestive contours implementation described in this paper ? http://gfx.cs.princeton.edu/gfx/pubs/DeCarlo_2003_SCF/DeCarlo2003.pdf thanks in advace suggestive_contours.hipnc
3. ## Perpenticular World Space Tangent on Surface

Thank you very much @satoru Doumo arigatou gozaimasu
4. ## Perpenticular World Space Tangent on Surface

Hi satoru thanks for your reply but unfortunately this is not working for my case i uploaded a new file to illustrate the issue i use polycut the result is the same as with boolean operations the unshared edges always produse two coincident polygons as petz said perpenticular_tangent_polycut.hipnc
5. ## Perpenticular World Space Tangent on Surface

i had no success determining whether or not a curve has its points ordered clockwise or anticlockwise float sum = 0.0; for (int i = 0; i < i@numpt; i++) { vector v1 = point(0,"P",i); vector v2 = point(0,"P",i+1) % i@numpt; sum += (v2.x - v1.x) * (v2.y + v1.y);// * (v2.z - v1.z); } setprimgroup (0, "reverse", @primnum, 0, "set"); if(sum > 0){ setprimgroup (0, "reverse", @primnum, 1, "set"); } obviously it is not right the above solution is for a 2d curve any idea for the 3d equivalent ?
6. ## Save and load chramp presets and other channels to a file

Hi is there an elegant way to save and load chramp presets to a file or more generally how do you store a combination of vars from a node to a file and load it ? so to avoid to copy the parameters and use a switch node to change between presets thanks in advance
7. ## Perpenticular World Space Tangent on Surface

that is ridiculously simple thanks a lot @petz any idea why the boolean operation reverses randomly the curve direction even when the same object copy is used to intersect ? i use various meshes not just planes to cut - intersect surfaces with the boolean operation and create the surface tangents perpendicular to the curves but there are inconsistency with the extracted curves is there any easy way to find those problematic curves and reverse them ? thanks in advance
8. ## Perpenticular World Space Tangent on Surface

Also i just noticed that there are problems with the initial direction of the tangents after the boolean operation some curves have their tangent direction reversed is there some easy way to clockwise all the curves ? thanks

Hi, have a look on this tutorial it explains quite well as how the volumesample and volumegradient work
10. ## Perpenticular World Space Tangent on Surface

Hello is there a more efficient way to calculate the world space tangent on a surface ? the method i use in the attached file seems limited as it uses boolean sections and polyframe to transfer the tangent to the surface any ideas on how to improve thanks in advance perpenticular_tangent.hipnc
11. ## Thickness mask to @Cd

Hi Aren, you can have a look at the file of how to use the intersect function to cast light rays with vex i think you should use the intersect_all for your thickness mask
12. ## Optimize Vex Shading - OpenGL implimentation

Hi community For my experiments I needed to write bake the diffuse lighting in the scene to the vertex colors in real time i just started using vex and i need your opinion on how to optimize the vex code i am thinking also to implement the same functionality with opengl how to write to a texture the vertex id and vertex color and read them back as color attributes ? i have done something similar is the past with hlsl and virtools it is most important that the obj should no contain any uvs any advise ? thanks Shading_Vex.hipnc
13. ## [SOLVED] Silhouette edges

Haha pixel perfect!!! even with 1000x1000 subdivisions its... rough at least these hillbillies are fast as long as you have some spare grid to divide...
14. ## [SOLVED] Silhouette edges

Thank you this is so great! i did some test with VDB from polygons -> VDB Topology to SDF -> Convert to polygons -> Clip but my results were not as accurate your solution is perfect much appreciated ioannis
15. ## [SOLVED] Silhouette edges

Hi miles thank you yes it could be done in that way but what i am asking is do we have 2d boolean operations in houdini ? is there a way to do this with vex? best regards ioannis
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