File Exchange

image thumbnail

Ray casting for deformable triangular 3D meshes

version 1.2.0.0 (257 KB) by Vipin Vijayan
Ray casting or collision detection for deformable triangular 3D meshes.

11 Downloads

Updated 19 Jun 2014

View License

This is a Matlab wrapper for OPCODE, which is a collision detection
or ray casting library for triangular 3D meshes.
OPCODE uses a couple of different aabb trees to store the mesh and this is
a pretty simple wrapper for one of the trees.

Nice thing about opcode is that it allows for deformable meshes,
meaning that you can update the mesh while it is stored in the tree,
which is much faster than what it takes to rebuild the aabb tree.

Input and output:

To make the tree:
tree = opcodemesh(v,f);
where
vertices v : 3 x nv
faces f : 3 x nf

To intersect:
[hit,d,trix,bary,Q] = tree.intersect(orig,dir);
where
starting points orig : 3 x nc
direction dir : 3 x nc
whether hit or not hit : nc x 1 logical
distance from orig to intersection point d : nc x 1
index into f of the intersection triangle trix : nc x 1
barycentric coordinates of the triangle that the rays intersected bary : 2 x nc
actual 3D coordinates of the intersection poitns Q : 3 x nc
If a ray misses, then you have 0's for trix and nan's for d,bary,Q at that index.

To get the actual 3D coords, you can also do
Qhit = repmat(1-B(2,:)-B(1,:),3,1).*v(:,f(1,T)) + ...
repmat(B(1,:),3,1).*v(:,f(2,T)) + ...
repmat(B(2,:),3,1).*v(:,f(3,T));
where B = bary(:,hit), T = trix(hit),
which gives you the coordinates at the intersected points.

To update the mesh with a new set of vertices (as in deform the mesh):
tree.update(vnew);
vnew : 3 x nv
vnew must be the same size and the original set of vertices.
The topology of the mesh cannot change.

To delete the tree (which is actually done automatically by Matlab when the variable is cleared):
tree.delete();

To compile, go to ./src_matlab
and run mexall.m
which compiles the mex code and copies it to ./matlab
(I compile it against everything in opcode, so it's a bit slow.)

To run the demo, go to ./matlab
and run opcodemeshdemo.m

OPCODE is in
http://www.lia.ufc.br/~gilvan/cd/
(which is a more portable version)
and
http://www.codercorner.com/Opcode.htm
(the original site)

Contains much appreciated code from
http://www.mathworks.com/matlabcentral/fileexchange/38964
for nicely wrapping C++ functions in a Matlab class.

Fixes from the previous version:
Fixed compile issues for Win64 by removing all of the assembly code.
You don't need to normalize the direction vectors anymore.
It also returns the actual points now instead of just the barycentric points.

Comments and Ratings (33)

Chao Wang

To help others, I put my building experience here. I just compiled it in matlab 2018b 64bit in win10, and only got one error:
------
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\xkeycheck.h(246): warning C4005: 'override': macro redefinition
c:\dev\kinectir\opcodemesh\opcode\Ice/IcePreprocessor.h(91): note: see previous definition of 'override'
C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\INCLUDE\xkeycheck.h(250): fatal error C1189: #error: The C++ Standard
Library forbids macroizing keywords. Enable warning C4005 to find the forbidden macro
------
This is actually because the code redefines C++ keyword 'override' in line 91 in IcePreprocessor.h. To fix it, I simply replace all the 'override' in ALL source code files in folder 'opcode' to some other words such as 'overrides'. I can build the code well after fixing this.

Thanks @ThT for your comment it helped me so much, I just want to add additional information to it as I faced other problems in Win10:
1) Install SDK 7.1 from http://www.microsoft.com/en-us/download/details.aspx?id=8279
>However, it fails to detect .NET framework 4. >> so continue the installation process as it is without the c++ compiler.
2) Then you can download c++ compiler "VC-Compiler-KB2519277.exe" manually at the following link: http://www.microsoft.com/en-us/download/details.aspx?id=4422 .
3)configure matlab to use this compiler in matlab by typing
"mex -setup C++" in matlab command window
then press the "Microsoft Windows SDK 7.1 (C++) "
hope it is useful for someone as well.

ThT

@Mohammad Alomari try to compile the lib with the winsdk-7.1 (windows sdk 7.1) compiler instead. That worked for me. The point is that there are some declarations in the opcode source code that in the new compilers are existing and that causes a conflict. Unfortunately the opcode library is not updated quite some years now.

@Ngo Nguyen @ThT
I have the same error
fatal error C1189: #error:
The C++ Standard Library forbids macroizing keywords. Enable
warning C4005 to find the forbidden macro.

can anyone help with compiling.
Thanks

ThT

@Ngo Nguyen I am getting the same error, did you manage to find a solution for it? @Philipp Ertl can I ask you how did you compile the lib in your case.

Thanks.

@Stefan Spelitz, @Vipin Vijayan. I think i found a solution for the bug. Although it might have created other bugs :D

use the following code in OPC_RayTriOverlap.h
https://pastebin.com/VeFhns4W

using the Example code of Stefan Spelitz the following results are calculated:
hit1 = true
hit2 = true

cheers.

ThT

@Stefan Spelitz, since the bug is on the original opcode you could contact the developers there given the links from Vipin Vijayan above.

Gaoli Sang

hello,
I am really appreciate your good job. I will help me a lot.
now, the first link you provided is invalid. so could you kindly send the code to my email? g.sang@utwente.nl. Thank you very much.

Thank you for looking into it anyway!

Thanks for describing the bug. I looked into it and it seems to be a bug in the original opcode. Unfortunately I won't be fixing it since it is too much effort.

I found a bug! Not all intersections are correctly detected. It seems to occur when shooting a ray orthogonal to the edge of a triangle. It depends on the winding of the triangles and/or side of the ray.

I cannot tell if the bug is already in the original opcode or in the Matlab bridge.

Example code:
f = [2 4 1 ; 2 3 4]';
v = [-1 -1 0 ; -1 1 0 ; 1 1 0 ; 1 -1 0]';
t = opcodemesh(v,f);
p1 = [0.0 0.0 -1]';
p2 = [0.0 0.0 1]';
[hit1,d1] = t.intersect(p1,(p2-p1)./norm(p2-p1)); % ok
[hit2,d2] = t.intersect(p2,(p1-p2)./norm(p1-p2)); % NOK

% Visualization:
trimesh(f',v(1,:),v(2,:),v(3,:));
hold on;
xlabel('x');
ylabel('y');
zlabel('z');
axis equal;
xlim([-2 2]);
ylim([-2 2]);
zlim([-2 2]);
plot3([p1(1) p2(1)], [p1(2) p2(2)], [p1(3) p2(3)], '-ro');
hold off;

Alla

Ngo Nguyen

Hi Vipin, I got the error:

C:\Program Files (x86)\Microsoft Visual Studio
14.0\VC\INCLUDE\xkeycheck.h(250): fatal error C1189: #error:
The C++ Standard Library forbids macroizing keywords. Enable
warning C4005 to find the forbidden macro.

Can you tell me how to fix it?
Thank you.

Really good.

One small thing to improve (could be much effort, though):

Also return multiple intersections, not only the first.

TCH

Here I put a test code but I cannot get the hit result that obviously shown in the figure(1). I am totally confused with the result, is there a bug in the original opcode?

@@@ code start

clc
clear
faces = [ ...
10 , 6 , 4 ; ...
11 , 6 , 10 ; ...
6 , 7 , 4 ; ...
10 , 4 , 13 ; ...
11 , 8 , 6 ; ...
16 , 11 , 10 ; ...
6 , 3 , 7 ; ...
4 , 7 , 2 ; ...
13 , 4 , 5 ; ...
14 , 10 , 13 ; ...
12 , 8 , 11 ; ...
8 , 3 , 6 ; ...
17 , 11 , 16 ; ...
16 , 10 , 14 ; ...
3 , 1 , 7 ; ...
7 , 0 , 2 ; ...
4 , 2 , 5 ; ...
13 , 5 , 9 ; ...
14 , 13 , 15 ...
] + 1;

vertices = [ ...
4.231401060000e-001 , 1.289017940000e-001 , 8.522257000000e-003 ; ...
4.234843750000e-001 , 1.295909270000e-001 , 8.482499000000e-003 ; ...
4.203841550000e-001 , 1.286728970000e-001 , 9.441268000000e-003 ; ...
4.212358700000e-001 , 1.298959500000e-001 , 9.275906000000e-003 ; ...
4.181593630000e-001 , 1.289744720000e-001 , 1.030612100000e-002 ; ...
4.176608580000e-001 , 1.284392850000e-001 , 1.045896700000e-002 ; ...
4.186631770000e-001 , 1.295075680000e-001 , 1.016991900000e-002 ; ...
4.208076170000e-001 , 1.292857210000e-001 , 9.348370000000e-003 ; ...
4.191720280000e-001 , 1.300382540000e-001 , 1.004999700000e-002 ; ...
4.151989140000e-001 , 1.282018740000e-001 , 1.154331100000e-002 ; ...
4.163471070000e-001 , 1.291179810000e-001 , 1.115785700000e-002 ; ...
4.169212040000e-001 , 1.295760350000e-001 , 1.096513000000e-002 ; ...
4.174953000000e-001 , 1.300340880000e-001 , 1.077240300000e-002 ; ...
4.157730100000e-001 , 1.286599270000e-001 , 1.135058400000e-002 ; ...
4.162002870000e-001 , 1.305507970000e-001 , 1.134597100000e-002 ; ...
4.156481020000e-001 , 1.302543030000e-001 , 1.150225100000e-002 ; ...
4.167558590000e-001 , 1.308455510000e-001 , 1.119693700000e-002 ; ...
4.173129270000e-001 , 1.311391140000e-001 , 1.105040500000e-002 ...
];

x = vertices(:,1);
y = vertices(:,2);
z = vertices(:,3);

orig0 = [0.41749369461334546, 0.12947887360062926, 0.010681338615420484]; % ray's origin
dir0 = [-0.40977066483612395, 0.15771530547732460, -0.89845082484126815]; % ray's direction

orig = orig0 - dir0 * 0.01;
orig0 = orig;

orig = [orig;orig];
dir = [dir0;-dir0];

endp = orig + dir * 0.1;
linex = [orig(:,1), endp(:,1)];
liney = [orig(:,2), endp(:,2)];
linez = [orig(:,3), endp(:,3)];

t = opcodemesh(vertices',faces');

tic;
[hit,d,trix,bary,Q] = t.intersect(orig',dir');
% intersect = TriangleRayIntersection(orig, dir, vert1, vert2, vert3);
fprintf('Number of: faces=%i, points=%i, intresections=%i; time=%f sec\n', ...
size(faces,1), size(vertices,1), sum(hit), toc);

%%
% *Display the results: Surface in blue, line in light read and intersected
% triangles in dark red*
figure(1); clf;
hold on;
trisurf(faces,x,y,z,'FaceAlpha', 0.9)
hold on;
plot3(linex,liney,linez,'-k', 'linewidth', 2);
hold on
plot3(orig0(1),orig0(2),orig0(3), '-bo');
% set(gca, 'CameraPosition', [106.2478 -35.9079 136.4875])
%set(gco,'EdgeColor','none');
xlabel('x');
ylabel('y');
zlabel('z');
axis tight

@@@ code end

I doubt it. I've never used the mesh to mesh collision function and I'm not really using this code much anymore.

Andre

Any chance to get the mesh to mesh collision function wrapped?

Eric

Great submission. Very useful.

Thank you Germano Gomes for mex64 advice.

Yeah, sorry about the confusion with norm(to-from). You're right, normc should be used for the input.

Note(ray casting): the correct value of 'd' is obtained by normalizing each column of the (to-from) 3xN matrix. I use Matlab normc for this:

[hit,d,trix,bary] = t.intersect(from,normc(to-from));

do not use:

[hit,d,trix,bary] = t.intersect(from,(to-from)./norm(to-from));

if you have more than one vector/ray

Very useful Matlab wrapper for fast collision detection and ray tracing.

For those using Matlab win64: look at the error information and comment out (//) the machine code (the __asm keyword invokes the inline assembler).

Example solution: error fix in IceFPU.h line 47:

//! Fast square root for floating-point values.
inline_ float FastSqrt(float square)
{
// #ifdef _MSC_VER
// float retval;
//
// __asm {
// mov eax, square
// sub eax, 0x3F800000
// sar eax, 1
// add eax, 0x3F800000
// mov [retval], eax
// }
// return retval;
// #else
return sqrt(square);
// #endif

In all cases just leave the code below #else (this is in vanilla C++) that does the same work without any incompatibility with win64.

Finally, unfortunately the returned d (matrix of distances) returns wrong values that seem to be scaled or shifted by the number of rays (vectors from-to), even if this vector is normalized as suggested by Vipin.
Vipin can you check and fix this please.

For it to be perfect I suggest returning the correct 'd' matrix, not needing the normalization step in Matlab and returning the intersection points(Q matrix) from the Mex function. That would be nice.

Thank you Vipin

I don't have an Matlab win64 install now. I tried it on win 32, os x 64, and linux 64. Maybe you can tell me what the error looks like and I will see what I can do.

omar

Thanks Vipin..now i've the same problem with K G...i get errors when compiling it under win 64 !

K G

how can I use it in Matlab(win64), it can not be mex in a 64bit system

The compiled file is not in your path or you didn't compile it.

omar

Hi...i get an error when i try to run the opcodemeshdemo.m in Matlab(2012b-64).

//
Undefined function 'opcodemeshmex' for input
arguments of type 'char'.

Error in opcodemesh (line 8)
this.objectHandle =
opcodemeshmex('create',
varargin{:});

Error in opcodemeshdemo (line 19)
t = opcodemesh(v',f');

//

any help ?

Thanks,
omar

Made a mistake in the previous comment. Calculation of Q should actually be like the following example.

f = [1 2 3]'; v = [-1 0 0.1 ; 1 1 0.1 ; 1 -1 0.1]';
t = opcodemesh(v,f);
from = [0.17 0.17 0.5]';
to = [0.17 0.17 -1]';
[hit,d,trix,bary] = t.intersect(from,(to-from)./norm(to-from));
B = bary(:,hit); T = trix(hit);
Q = repmat(1-B(2,:)-B(1,:),3,1).*v(:,f(1,T)) + repmat(B(1,:),3,1).*v(:,f(2,T)) + repmat(B(2,:),3,1).*v(:,f(3,T));

You had to normalize the direction (to - from) and I had gotten the calculation for the points Q wrong. I will upload a version eventually so you don't have to normalize the direction. Btw, here is an example that works:

f = [1 2 3]'; v = [-1 0 0.1 ; 1 1 0.1 ; 1 -1 0.1]';
t = opcodemesh(v,f);
from = [0 0 0.5]';
to = [0 0 -1]';
[hit,d,trix,bary] = t.intersect(from,(to-from)./norm(to-from));
B = bary(:,hit); T = trix(hit);
Q = repmat(B(1,:),3,1).*v(:,f(3,T)) + repmat(B(2,:),3,1).*v(:,f(2,T)) + repmat(1-B(2,:)-B(1,:),3,1).*v(:,f(1,T));

Zhou

I used the code following the descriptions.
i have one questions:
(1) why d is not equal to norm(orig-Q)?

(2) The following simple example can not obtian right result (d=0.5, Q=[0 0 0]). (i get a wrong result: d =0.3333, Q = [0.5 -0.25 0]
==================
v = [-1 0 0 ; 1 1 0 ; 1 -1 0];
f = [1 2 3];
t = opcodemesh(v',f');

from = [0 0 0.5]';
to = [0 0 -1]';
[hit,d,trix,bary] = t.intersect(from,to-from);

Q = repmat(bary(1,:),3,1).*v(f(trix,1),:)' + ...
repmat(bary(2,:),3,1).*v(f(trix,2),:)' + ...
repmat(1-bary(1,:)-bary(2,:),3,1).*v(f(trix,3),:)'
===========

I do not know why?

Thanks!

PS. The getting the points part should actually look like

Q = repmat(B(1,:),3,1).*v(:,f(1,T)) + ...
repmat(B(2,:),3,1).*v(:,f(2,T)) + ...
repmat(1-B(2,:)-B(1,:),3,1).*v(:,f(3,T));
where B = bary(:,hit), T = trix(hit).

Updates

1.2.0.0

Fixed compile issues for Win64 by removing all of the assembly code.
You don't need to normalize the direction vectors anymore.
It also returns the actual points now instead of just the barycentric points.

1.1.0.0

Fixed compile issues for Win64 by removing all of the assembly code.
You don't need to normalize the direction vectors anymore.
It also returns the actual points now instead of just the barycentric points.

MATLAB Release Compatibility
Created with R2013a
Compatible with any release
Platform Compatibility
Windows macOS Linux

opcodemesh/matlab/

opcodemesh/src_matlab/