Hi all.
I have suffering a problem with 3D Textures that hadn't happened in previous versions.
When i render an atmosphere with the standar shaders for 3D textures i get this image:

This is the same image in tiff format with alpha:
http://personales.ya.com/lisux/3dTextureColor.tif [personales.ya.com]
The alpha is right, i am not using adaptative step, the resolution is 128 for all the axes, and the step size 0.05.
I am trying to access to the density information from a shader too. Using the 3DTexture VOP i get always zero values.
Here is the 3D Texture:
http://personales.ya.com/lisux/sprites.0748.i3d [personales.ya.com]

Why this results?
I am using Houdini 8.0.499 with Ubuntu 5.10

lisux
Hi all.
I have suffering a problem with 3D Textures that hadn't happened in previous versions. When i render an atmosphere with the standar shaders for 3D textures i get this image:
http://personales.ya.com/lisux/sprites.0748.i3d [personales.ya.com]

Why this results?
I am using Houdini 8.0.499 with Ubuntu 5.10

I'm not sure why you're getting those results. When I run the i3d file through this VEX COP, things look pretty much like I'd expect.


/*%vcc -l copview3d.otl %
*/
#define VOP_OP
#define VOP_COP2

#pragma opname cop2gen1
#pragma oplabel “VEX View I3D File”
#pragma opmininputs 0
#pragma opmaxinputs 0
#pragma label zval “Z Value”
#pragma range zval 0 1
#pragma label trans Translate
#pragma label rot Rotate
#pragma label scale Scale

#include <voptype.h>
#include <voplib.h>

cop2
copview3d(string map=“/tmp/sprites.0748.i3d”;
float zval = 0;
vector trans = { 0, 0, 0 };
vector rot = { 0, 0, 0 };
vector scale = { 1, 1, 1 };
vector pivot = {0,0,0})
{
int bound_zval;
int bound_trans;
int bound_rot;
int bound_scale;
vector vec;
vector xformpos;
float i3dval;

bound_zval = isbound(“zval”);
vec = vop_floattovec(X, Y, zval);
bound_trans = isbound(“trans”);
bound_rot = isbound(“rot”);
bound_scale = isbound(“scale”);
xformpos = vec * invert(maketransform(0,0,trans,rot,scale,pivot));
i3dval = texture3d(“/tmp/sprites.0748.i3d”, “density”, xformpos,
“filter”, “box”, “width”, 1);
R = i3dval;
}


To test this

% vcc -l /tmp/copview3d.otl copview3d.vfl
% houdini /tmp/copview3d.otl


Add a “VEX View I3D File” and see what you get.

Thans Mark.
Yes the 3d texture is correct.
I don't know exactly why but creating a new mantra ROP and rerender all goes right.
Maybe some wrong setting.
Very useful your example, with some retouching one can “fake” volumetrics in post, that's great!