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From: Louis B. <ba...@sc...> - 2005-01-21 06:11:31
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On Thursday 20 January 2005 22:43, Claudio Silva wrote: > What is the blue curve? The blue curve corresponds to simple vertex arrays in immediate mode (no VBO, no display list). This is the method used when VBOs are not manually enabled when running configure or cmake. Louis |
From: Claudio S. <cs...@cs...> - 2005-01-21 05:43:19
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Louis, What is the blue curve? Thanks, Claudio. On Jan 20, 2005, at 6:11 PM, Louis Bavoil wrote: > On Thursday 06 January 2005 20:17, Wagner T Correa wrote: >> We used to use Vector_3f for normals. I changed it to Vector_3b >> because >> it was a pretty significant savings in storage. For out-of-core >> appplications, where the bottleneck is disk I/O, that's very >> important. > > You're right. I confirm that disk I/O is the bottleneck of iwalk when > rendering out-of-core datasets. > > I compared the frame rates of iwalk on Powerplant on a camera path > using > different rendering methods. > > See the plots attached. The green curve was generated by fetching > GL_FLOAT > normals from the disk, and the red curve by fetching GL_BYTE normals > and > converting the bytes to float when loading the VBOs. > > For the record, I used: > ./iwalk --camera-path /scratch/cameras/powerplant/pp8.path > --target-frame-rate 50 --vertex-budget 1000000 > /scratch/models/gtb/powerplant/powerplant.oct.50000.d/oct > > I have just updated gtb/graphics/VBO.{hpp,cpp} in the main trunk: > > * gtb/graphics/VBO.cpp, gtb/graphics/VBO.hpp: > Now uses GL_FLOAT for normals instead of GL_BYTE. > > Louis<pp8-vbos-vs-stream.ps> |
From: Louis B. <ba...@sc...> - 2005-01-21 01:11:49
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On Thursday 06 January 2005 20:17, Wagner T Correa wrote: > We used to use Vector_3f for normals. I changed it to Vector_3b because > it was a pretty significant savings in storage. For out-of-core > appplications, where the bottleneck is disk I/O, that's very important. You're right. I confirm that disk I/O is the bottleneck of iwalk when rendering out-of-core datasets. I compared the frame rates of iwalk on Powerplant on a camera path using different rendering methods. See the plots attached. The green curve was generated by fetching GL_FLOAT normals from the disk, and the red curve by fetching GL_BYTE normals and converting the bytes to float when loading the VBOs. For the record, I used: ./iwalk --camera-path /scratch/cameras/powerplant/pp8.path --target-frame-rate 50 --vertex-budget 1000000 /scratch/models/gtb/powerplant/powerplant.oct.50000.d/oct I have just updated gtb/graphics/VBO.{hpp,cpp} in the main trunk: * gtb/graphics/VBO.cpp, gtb/graphics/VBO.hpp: Now uses GL_FLOAT for normals instead of GL_BYTE. Louis |
From: Wagner T C. <wtc...@dc...> - 2005-01-07 03:17:27
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Hi Louis, We used to use Vector_3f for normals. I changed it to Vector_3b because it was a pretty significant savings in storage. For out-of-core appplications, where the bottleneck is disk I/O, that's very important. For in-core applications, that may not matter. This problem has come up before. The difficulty is that a vertex can have many different attributes (position, color, normal, texture coordinates), each of these attributes can have many different numbers of components, and each componenent can have many different types. Just to give you an idea: position: glVertex[2,3,4][d,f,i,s] (12 cases) color: glColor[3,4][b,d,f,i,s,ub,ui,us] (16 cases) normal: glNormal3[b,d,f,i,s] (5 cases) texture coordinates: glTexCoord[1,2,3,4][d,f,i,s] (16 cases) possible combinations: 15360! Ideally we should be able to have any combination of these things, but currently we are hardwiring one of them. This is one of the biggest problems with GTB right now. A while ago Claudio, Walter, and I were trying to come up with a flexible way to specify vertex data, but we never finished it. If you want and have the time, you could write a new class that allows combinations of attributes, components, and types. Instead of trying to support all possible combinations, you could support just the 14 that are supported by glInterleavedArrays(). But if you just want something working quickly, please don't change the current class. Intead, please clone it, rename it, and then change the normal field. Regards, Wagner Louis Bavoil wrote: > Hi, > > If am thinking to change the data type of the normals in GTB from Vector_3b to > Vector_3f. VBOs are infinitely slow with GL_BYTE, but with GL_FLOAT normals, > they are faster than display lists of vertex arrays, to load and to render > (See http://www.sci.utah.edu/~bavoil/opengl/vbo/). > > Please let me know by the end of the week if you are against the change. > > Louis |
From: Louis B. <ba...@sc...> - 2005-01-06 03:48:07
|
Hi, If am thinking to change the data type of the normals in GTB from Vector_3b to Vector_3f. VBOs are infinitely slow with GL_BYTE, but with GL_FLOAT normals, they are faster than display lists of vertex arrays, to load and to render (See http://www.sci.utah.edu/~bavoil/opengl/vbo/). Please let me know by the end of the week if you are against the change. Louis |
From: Louis B. <ba...@sc...> - 2004-08-22 22:29:28
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Date: Sun, 22 Aug 2004 09:29:46 -0600 From: Sinesio Pesco <pe...@sc...> To: Louis Bavoil <ba...@sc...> Cc: "zheng furen" <dua...@ho...> Subject: Re: How to get GTB(Graphics ToolBox) SHAPE_FILE or color map file etc.? Hi Zheng, for Volume rendering you need to create the octree too. So after the: $ off-tetra-to-gtb mesh.off mesh.gtb mesh.tsc You need to create the octree: $ octree-init mesh,gtb mesh.oct.d (in fact not working in this way: there was a little bug in the program here, so you need to put the complete path of your file in the command above. For example, if your file is in the /home/usr/zheng/myproject, use: $ octree-init /home/usr/zheng/myproject/mesh.off /home/usr/zheng/myproject/mesh.oct.d After this you need to compute the centroids of the tetra using: $ tetra-oct-init mesh.oct.d/oct After this you can execute. To Execute we normally use the makefile (see tests.am) to set all the parameters, for example (extract of the tests.am): mesh-oct: gtb-view GTB_CACHE_MAX_SIZE=`expr 256 \* 1024 \* 1024` \ GTB_CACHE_MAX_FETCH_THREADS=8 \ GTB_CACHE_MAX_PREFETCH_THREADS=1 \ GTB_CACHE_MAX_PREFETCH_AMOUNT_PER_FRAME=`expr 1 \* 1024 \* 1024` \ GTB_CACHE_MAX_PREFETCH_REQUEST_AGE=10 \ GTB_OCTREE_RENDERER=Tetra_octree_renderer \ ./gtb-view \ /home/usr/zheng/myproject/mesh.oct.d/oct \ -c /home/usr/zheng/myproject/color.txt \ -d /home/usr/zheng/myproject/density.txt \ -s /home/usr/zheng/myproject/mesh.tsc In attach, there is a trivial complete example (including: three.off, the color.txt and density.txt). You can use this color.txt and density.txt for any example that you have. |
From: Louis B. <ba...@sc...> - 2004-08-22 22:29:08
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Date: Sun, 22 Aug 2004 03:26:36 +0200 From: Louis Bavoil <ba...@sc...> To: "zheng furen" <dua...@ho...> Cc: Sinesio Pesco <pe...@sc...> Subject: Re: How to get GTB(Graphics ToolBox) SHAPE_FILE or color map file etc.? Zheng, I have never used the volume renderer of GTB but I worked with gtb-view and the gtb_volume_rendering library. Here is my understanding of how to use the volume renderer: - Assuming you have an tetrahedral mesh in the OFF format, you need first to convert the OFF file to the GTB Indexed_tetra_set (SHAPE_FILE) using the program off-tetra-to-gtb: $ off-tetra-to-gtb mesh.off SHAPE_FILE SCALAR_FILE - Next, you need a color map and a density map. Look at the code of GTB to see the format of these files. - Finally, you should be able to do direct volume rendering of the SHAPE_FILE with: $ gtb-view -c COLOR_MAP -d DENSITY_MAP -s SCALAR_FILE SHAPE_FILE Sinesio: Do you agree with the above? Could you add any precision about the color and density maps? -- Louis On Sun, 22 Aug 2004 12:09:16 +0800 "zheng furen" <dua...@ho...> wrote: > Hi, > I am now a Ph.D student in Beijing Institute of Technology of China. I am > working at VR platform rendering optimization. > I have compiled GTB successully and now I just do some testing on GTB,would > you like to tell me how I can get GTB shape file or color map file and so > on?If I cannt have these files ,I can do nothing. > 1:For example,I hope to compile oct-creat.cpp,but I cant find SHAPE FILE, > ------------------------------ > "Usage: %s [OPTION]... SHAPE_FILE OCTREE_DIR\n" > "Create an octree from SHAPE_FILE, writing output to OCTREE_DIR\n" > "\n" > " -b X1 Y1 Z1 X2 Y2 Z2 Set the bounding box.\n" > " -h Display this help and exit.\n" > " -v MAX_VERTICES_PER_NODE Set the maximum number of vertices per node.\n" |