NV_POINT_SPRITE

[Adrian]

Hi guys, I want to try out the new point sprite extension but after having read the spec a few times I'm not sure how to implement it. There doesn't seem to be a tutorial/demo for it yet. Does anyone know how to use it? Presumably I need to bind a texture, enable NV_POINT_SPRITE then render the points? enabling Texture_2D and drawing with points is slow and draws nothing. Looking at the spec I think I need to use COORD_REPLACE_NV somewhere but I'm not sure where/why.

Will the point sprite size vary with Z or will it behave like GL_POINTS?

Thanks

[mcraighead]

You need to call, for each texture unit that you want point sprite texture coordinate generation:

glTexEnvi(GL_POINT_SPRITE_NV, GL_COORD_REPLACE_NV, GL_TRUE);

You can set this on any or all texture units.

On the other hand, the point sprite R coordinate mode (zero, S, or R) is global across all texture units.

- Matt

[Adrian]

Ok thanks but I was looking for more along the lines of (and this doesnt work but its the way I'm currently doing it)


#ifndef GL_NV_point_sprite
#define POINT_SPRITE_NV 0x8861
#define COORD_REPLACE_NV 0x8862
#define POINT_SPRITE_R_MODE_NV 0x8863
#endif

glEnable(GL_TEXTURE_2D);
glPixelStorei(GL_UNPACK_ALIGNMENT, 4);
glGenTextures(1,&Texture);
glBindTexture(GL_TEXTURE_2D, Texture);

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_S,GL _CLAMP);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_WRAP_T,GL _CLAMP);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTE R,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTE R,GL_LINEAR);

glTexEnvf(POINT_SPRITE_NV,COORD_REPLACE_NV,GL_TRUE );


Load Texture....

Main Loop

glEnable(POINT_SPRITE_NV);
glEnable(GL_TEXTURE_2D); (should this be enabled?)
glBindTexture(GL_TEXTURE_2D, Texture); (I must need this surely)
glBegin(GL_POINTS);

Loop through points and render using a single glVertex and glColor. I dont need glTexCoord2f do I?

glEnd();

With GL_TEXTURE_2D enabled its very slow and draws nothing, with it disabled I just get the standard points.

I have an original Geforce 3 and detonatots 27.7, it should work on this hardware/driver config right?

[tcobbs]

Originally posted by Adrian:
I have an original Geforce 3 and detonatots 27.7, it should work on this hardware/driver config right?

Not according to the compatibility matrix at the beginning of the document, it won't. It's listed as NV25 only.

[Adrian]

Damn, you're right, I only checked the txt document. I kind of assumed since I can see point sprites in the 3D mark I would get it with OpenGL to. Thanks for pointing that out.

[wimmer]

doesn't the compatibility matrix in nvopenglspecs.pdf refer only to the driver version? E.g., GL_EXT_multi_draw_arrays is listed for R25 on NV1x, and I have it in my extension string (GF2). Just check your extensions string to be sure...

Michael

[Adrian]

I've checked my extension string it's not there. Interestingly NV_POINT_SPRITE is the only extension only available on the Geforce 4. I would have thought it could be emulated on older hardware...

[davepermen]

point_sprites and texture_shaders3 i guess..

too bad, i waited for point_sprites in gl now over one year for my gf2mx..

[Adrian]

According to the pdf, texture shader3 is emulated on nv1x but you'll need the latest drivers(R25) for it.

[Humus]

NVidia has GL_NV_point_sprite, ATi has GL_ATIX_point_sprite. What about making an EXT?

Just a thought ...