Monthly Archives: February 2007

Back to work, Mars r622

Yesterday my exams session finally ended, I’m really satisfied about the results achieved, but during the studying period I was eager to get back to coding…

Today I fixed bug #0000008, a fastidious one which caused program termination if the user tried to take a screenshot after having deleted the hidden directory inside his home where settings and images are saved by default. 🙂

Mars 0.1.1 2nd

The first thing I thought was that I was missing a fopen() return code check, but, fortunately for my reputation, it wasn’t the case. 😉

// Opening output file
if((fp = fopen(filename, "wb")) == NULL)
  throw Exception("Screen", "fopen error");
  return -1;

The problem, as the shell output was suggesting, was related to the exception system: the fopen() exception was never caught.

Just changing this:

case SDLK_F4:

into this:

case SDLK_F4:
  catch(Exception e)

fixed everything.

Have a look at r622 log and at mars.cpp changes and remember to catch all the exception you may throw. 😉

Blender 2.43

Today is a memorable day for Blender!
First of all got a massive redesign and it’s now really cool and professional. For instance, have a look at the new features page, I think it’s a perfect showcase for our beloved program.

Moreover Blender 2.43 was released!

Blender 2.43 Splash

As usual the release log is full of appealing new functionalities that I’m eager to try.
Some of them can be previewed in feature videos or tested using the blend files which come inside the archive.

I would like to express my congratulations to the whole Blender community.

The quest for the lost fragment

Yesterday I was donated a new graphic card from a generous guy at the university, including cables, manual and bundled software, it is a nice MSI G4Ti4200-DT64 with red PCB.

MSI G4Ti4200-DT64

It’s a good card but unfortunately it has only a primitive version of pixel shaders, they are neither floating point (supporting at most the proprietary “HILO” format) nor GLSL compliant, and they cannot be used via GL_ARB_fragment_program (as a matter of fact it is not present in the extensions array 🙁 ), but only through the family of GL_NV_register_combiners and GL_NV_texture_shader functions, which make use of the OpenGL state machine.
Nvidia Cg actually supports the fp20 profile, but its output is just a nvparse program, which has to be passed to a function that will setup GL texture states.

Anyway, let’s analyze what’s new going from a GeForce4 MX440-8X (NV18) to a GeForce4 Ti 4200 (NV25):

  • The OpenGL version string hasn’t changed (mainly because of the lack of Shader Model 2.0), it is still 1.5.8.
  • Thanks to the Accuview AA Engine there are three new anti-aliasing modes: 4x Bilinear Multisampling, 4x Gaussian Multisampling and 2x Bilinear Multisampling by 4x Supersampling.
  • There are twenty new extensions available, most of them are related to multisample, depth textures, occlusion queries, shadows and texture shaders:
    GL_ARB_depth_texture, GL_ARB_multisample, GL_ARB_occlusion_query, GL_ARB_shadow, GL_ARB_texture_border_clamp, GL_EXT_shadow_funcs, GL_EXT_texture3D, GL_EXT_timer_query, GL_HP_occlusion_test, GL_NV_copy_depth_to_color, GL_NV_depth_clamp, GL_NV_multisample_filter_hint, GL_NV_occlusion_query, GL_NV_register_combiners2, GL_NV_texture_compression_vtc, GL_NV_texture_shader, GL_NV_texture_shader2, GL_NV_texture_shader3, GL_SGIX_depth_texture, GL_SGIX_shadow.

Of course I performed some benchmarks too (have a look at Electron specs), all at 1024×768, except from glxgears and globs tests, they were run at the default 640×480 resolution.
Quake 3 was tested on the four.dm_68 demo with sound, Blender 2.42 was tested with the draw benchmark, while the GLSLvp_pointz test uses only vertex shader to move and color points.
Note that this last test is emulated in software on NV18 while is performed in hardware on the NV25, but shaders plus full scene anti-aliasing seem to be impossible to achieve on the latter.

Test NV18 NV25
NoAA, NoAF 2xAA, 4xAF NoAA, NoAF 2xAA, 4xAf
glxgears 1568.5 833.5 2976.7 1571.7
Blender 2580 1580 7000 4484
Quake 3 93.0 51.7 113.6 92.3
gl_shadow 296 148.4 674.6 360
gl_pointz 421.8 272.6 526.2 398.4
gl_blit 600.6 285.8 1197.4 612.4
gl_smoke 299 177.2 404.2 302
GLSLvp_point 118.6 103.8 317.6 X

The card is nice and fast, but the search for the fragment (extension) has not ended. 😉