Re: [osg-users] geometry and normals
STTrife wrote: Anyway you have indexed vertices obviously, but you can also use non-indexed vertices. In that case you just specify the vertices for each triangle separately. That's basically my first implementation and the reason why I asked confirmation here was to understand which is the better way in my case. In a road I have always adjacent triangles (holes or disjointed parts are very rare) so I think what Robert suggested is the proper solution. STTrife wrote: Now I've confused myself :P I was too, that's why I asked here ;) Regards Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60464#60464 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
it seems like you are using referenced vertices in your roads mesh? (at least that is what I understand from int* oConnections (the int references vertices indexes right?) I think that if you want to use the accelerated drawing you should convert it to simple vertex arrays, where the vertices are not indexed. -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60455#60455 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Hi STTrife, which is the difference between what you say and what Robert suggested here? robertosfield wrote: As for memory/GL efficiency, the most efficient way to the geometry to the GPU is to use index primitives via the osg::DrawElements* primitive set, this allows you to share vertex, normal, texture coordinate data etc. Regards, Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60457#60457 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Well to give better advice, I would need to understand what is exactly stored in float* oPoints and int* oConnections. What I assume is that oPoints (an array of floats) contains x1,y1,z1,x2,y2,z2, etc. and then oConnections (an array of ints) contains a serie of references to those points for example 2 refers to x2,y2,z2. Maybe you could first tell something about this (if this is correct or not) before I comment further... maybe I misunderstand what is in those arrays... -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60458#60458 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
OK,
this is an exaple (flat square road):
Code:
osg::Geometry* geometry = getGeometry();
osg::Vec3 myCoords[] =
{
osg::Vec3(-1.0f,1.0f,0.0f),
osg::Vec3(-1.0f,-1.0f,0.0f),
osg::Vec3(1.0f,-1.0f,0.0f),
osg::Vec3(1.0f,1.0f,0.0f)
};
int numCoords = sizeof(myCoords)/sizeof(osg::Vec3);
geometry-setVertexArray(new osg::Vec3Array(numCoords,myCoords));
unsigned short myIndices[] =
{
0,
1,
2,
0,
2,
3
};
int numIndices = sizeof(myIndices)/sizeof(unsigned short);
geometry-addPrimitiveSet(new
osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLES,numIndices,myIndices));
Gianni
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Re: [osg-users] geometry and normals
First: In your example the coordinates are stored in an array of Vec3, but in the other code you posted, the oPoints is an array of float so there seems to be a bit of a contradiction there? Anyway you have indexed vertices obviously, but you can also use non-indexed vertices. In that case you just specify the vertices for each triangle separately. When I started working on my project I heard or read that this is better, because it can be handled faster by modern graphics card (something about the card not being able to use the fasted render path when indices are used), and the extra memory it takes is less important because modern graphics cards have plenty of memory. But I can't find a solid source on that now so I'm really starting to doubt if this is (still) true... -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60460#60460 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Hi Bram, Most modern hardware will be best driven using indexed primitives sets rather than duplicating vertices - it typically wins on memory bandwidth and ability to utilize the vertex cache on the GPU. If the amount of shared indices is low then duplicating vertices is likely to be better. Robert. On 25 July 2014 14:30, Bram Vaessen bram.vaes...@gmail.com wrote: First: In your example the coordinates are stored in an array of Vec3, but in the other code you posted, the oPoints is an array of float so there seems to be a bit of a contradiction there? Anyway you have indexed vertices obviously, but you can also use non-indexed vertices. In that case you just specify the vertices for each triangle separately. When I started working on my project I heard or read that this is better, because it can be handled faster by modern graphics card (something about the card not being able to use the fasted render path when indices are used), and the extra memory it takes is less important because modern graphics cards have plenty of memory. But I can't find a solid source on that now so I'm really starting to doubt if this is (still) true... -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60460#60460 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Hi Robert, one more question. I would like to implement a method in my core class to get vertices and indices to use both in osg geometry and in a wavefront writer. The problem is the array type. I don't want to write the same code twice one for the wavefront writer and one for osg geometry just because they use different array/vector types. The wavefront writer can use C arrays or std::vectors. I see that a C array can be used in a DrawElementsUShort constructor. On the other side setVertexArray gets an osg::Array as parameter. I'm trying to understand how to use a C array or a std::vector instead. In any case at a certain point I have memory allocation for vertices and indices twice (the array I created and the copy for osg geometry). Regards, Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60430#60430 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
HI Giannu, I can't work out what your one more question is, I've re-read what you written and am just as confused. Robert. On 24 July 2014 11:43, Gianni Ambrosio g.ambrosio+...@gmail.com wrote: Hi Robert, one more question. I would like to implement a method in my core class to get vertices and indices to use both in osg geometry and in a wavefront writer. The problem is the array type. I don't want to write the same code twice one for the wavefront writer and one for osg geometry just because they use different array/vector types. The wavefront writer can use C arrays or std::vectors. I see that a C array can be used in a DrawElementsUShort constructor. On the other side setVertexArray gets an osg::Array as parameter. I'm trying to understand how to use a C array or a std::vector instead. In any case at a certain point I have memory allocation for vertices and indices twice (the array I created and the copy for osg geometry). Regards, Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60430#60430 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
OK, is there a way to pass a C array to geometry-setVertexArray()? Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60432#60432 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Hi Gianni, this is more into STL programming. This link explains cheap conversion between C array and STL vector http://stackoverflow.com/questions/1733143/converting-between-c-stdvector-and-c-array-without-copying Nick On Thu, Jul 24, 2014 at 1:28 PM, Gianni Ambrosio g.ambrosio+...@gmail.com wrote: OK, is there a way to pass a C array to geometry-setVertexArray()? Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60432#60432 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org -- trajce nikolov nick ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Hi Nick, no this is not a problem of converting C arrays to stl vectors. I'm going to explain the case in detail soon .. Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60434#60434 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Here I am with an example that explains my scenario.
I commented the code with questions, hoping this is clearer.
Code:
// This is a core road that contains all data and must not know of OSG at all
class Road
{
// This method builds vertices and indexes based on the internal data
// It must not use osg::Arrays but C arrays or std::vectors
void getPointsAndConnections(float* oPoints, int oPointSize, int*
oConnections, int oConnectionSize);
}
// This class can not use OSG classes either (so no osg::Array here)
class WaveFrontWriter
{
// This method is pleased to use getPointsAndConnection() since it
returns useful data.
// Here I can use a C array of an std::vector, not osg::Array
void write(Road* road) {
road-getPointsAndConnections(vertices, vsize, indices, isize);
// here vertices, vsize, indices, isize are used for writing
the file ...
}
}
// Here is the 3D representation of the road
class OsgRoad
{
// This method is also pleased to use getPointsAndConnection() of Road
core class
void draw(Road* road) {
road-getPointsAndConnections(vertices, vsize, indices, isize);
osg::Geometry* geometry = new osg::Geometry();
// how to use incoming C arrays (or std::vectors would be also
nice) in the following call?
geometry-setVertexArray(what here?);
// the following call luckily accepts C arrays but ...
// 1) does it make a copy of the passed C array? (if so, that
means memory duplication in my case)
// 2) if not, is it responsible of deallocation?
addPrimitiveSet(new
osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLES, isize, indices));
}
}
Thank you in advance.
Gianni
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Re: [osg-users] geometry and normals
HI Gianni,
An osg::Array subclass like Vec3Array is a std::vector so you can use
all your usual std::vector access methods and code for it. Sample
applies to DrawElementsUShort.
The easist way to manage things would be simply have your road code build
it using osg::Vec3Array, or get it to fill in the std::vector passed in
from external OSG glue code that passes in the std::vector from the
Vec3Array, i.e.
void MyClass::MyMethodPopulatingVertexData(std::vectorVec3 vertices)
{
fill in data
}
myobject-MyMethodPopulatingVertexArray(*vec3Array);
If don't want to even integrate the std::vectorVec3 but have your own
equivilant to Vec3 then you'll end up needing to copy the data across to
Vec3Array yourself or go the more complicated route of implementing your
own osg::Array subclass to integrate your own data. The later requires
more work to glue it together though, you'll need to look at existing
osg::Array subclasses for guidance on how to do this.
Robert.
On 24 July 2014 13:54, Gianni Ambrosio g.ambrosio+...@gmail.com wrote:
Here I am with an example that explains my scenario.
I commented the code with questions, hoping this is clearer.
Code:
// This is a core road that contains all data and must not know of OSG at
all
class Road
{
// This method builds vertices and indexes based on the internal
data
// It must not use osg::Arrays but C arrays or std::vectors
void getPointsAndConnections(float* oPoints, int oPointSize,
int* oConnections, int oConnectionSize);
}
// This class can not use OSG classes either (so no osg::Array here)
class WaveFrontWriter
{
// This method is pleased to use getPointsAndConnection() since it
returns useful data.
// Here I can use a C array of an std::vector, not osg::Array
void write(Road* road) {
road-getPointsAndConnections(vertices, vsize, indices,
isize);
// here vertices, vsize, indices, isize are used for
writing the file ...
}
}
// Here is the 3D representation of the road
class OsgRoad
{
// This method is also pleased to use getPointsAndConnection() of
Road core class
void draw(Road* road) {
road-getPointsAndConnections(vertices, vsize, indices,
isize);
osg::Geometry* geometry = new osg::Geometry();
// how to use incoming C arrays (or std::vectors would be
also nice) in the following call?
geometry-setVertexArray(what here?);
// the following call luckily accepts C arrays but ...
// 1) does it make a copy of the passed C array? (if so,
that means memory duplication in my case)
// 2) if not, is it responsible of deallocation?
addPrimitiveSet(new
osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLES, isize, indices));
}
}
Thank you in advance.
Gianni
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Re: [osg-users] geometry and normals
Hi Gianni,
The SmoothingVisititor is really just a fallback for when no normals are
provided with a model, the best way to get the precisely the result you
want is to provider per vertex normals.
As for memory/GL efficiency, the most efficient way to the geometry to the
GPU is to use index primitives via the osg::DrawElements* primitive set,
this allows you to share vertex, normal, texture coordinate data etc.
Robert.
On 23 July 2014 13:59, Gianni Ambrosio ga...@vi-grade.com wrote:
Hi All,
I need to draw a surface. Looking at OSG examples I implemented it this
way:
Code:
osg::Geometry* geometry = getGeometry();
osg::Vec3Array* vertices = new osg::Vec3Array;
GraphicVectorPtr graphicVector = road-graphicVector();
size_t count = graphicVector-count();
size_t addedPoints = 0;
vertices-reserve(count * 3);
for (size_t i = 0; icount; ++i) {
const GraphicItem item = (*graphicVector)[i];
if (item.points.size() == 9) {
vertices-push_back(osg::Vec3(item.points[0], item.points[1],
item.points[2]));
vertices-push_back(osg::Vec3(item.points[3], item.points[4],
item.points[5]));
vertices-push_back(osg::Vec3(item.points[6], item.points[7],
item.points[8]));
addedPoints+=3;
}
}
geometry-setVertexArray(vertices);
geometry-addPrimitiveSet(new
osg::DrawArrays(osg::PrimitiveSet::TRIANGLES, 0, addedPoints));
Now, first of all I would like to know if this is correct. I mean I want
to draw triangles and I don't want to waste memory.
The problem is that I see a basically flat surface. I tried then with a
SmoothingVisitor on the geometry and the flat surface problem is solved. So
I guess it was related to normals not set, right?
Now, since I don't like so much how the surface is rendered with the
SmoothingVisitor, is there a way of render the surface as it is drawn?
Regards,
Gianni
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Re: [osg-users] geometry and normals
Hi Robert, just because I had in mind a thread in this forum where it seems, on the contrary, that was NOT recommended for GL efficiency. Do you mean something like the code inside createBackground() of osggeometry.cpp example? polyGeom-setVertexArray(new osg::Vec3Array(numCoords,myCoords)); ... polyGeom-addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLE_STRIP,numIndices,myIndices)); so, basically the same content of a obj/wavefront file? Regards, Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60412#60412 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
HI Gianni, On 23 July 2014 16:25, Gianni Ambrosio ga...@vi-grade.com wrote: Hi Robert, just because I had in mind a thread in this forum where it seems, on the contrary, that was NOT recommended for GL efficiency. What isn't recommend is using the deprecated osg::Geometry::setVertex/Color/Normal/etc./Indices(..) functionality, sharing vertices via vertex indices isn't supported by OpenGL and has to be simulated by caching vertex data on the CPU and then send this as a buffer. In OSG-3.2 these methods are deprecated and will be removed completely from OSG-3.4 onwards. Do you mean something like the code inside createBackground() of osggeometry.cpp example? polyGeom-setVertexArray(new osg::Vec3Array(numCoords,myCoords)); ... polyGeom-addPrimitiveSet(new osg::DrawElementsUShort(osg::PrimitiveSet::TRIANGLE_STRIP,numIndices,myIndices)); Using DrawElementsUShort is the correct way to provide indices and is fully supported by OpenGL and is the recommend way to provide primitive data where vertices can be shared. Robert. ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
Re: [osg-users] geometry and normals
Thank you Robert for explanation and clarification. Gianni -- Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=60415#60415 ___ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
