OGL Question: Are all vertex sent to de GPU?

[casty]

Hi,

If I have an SceneNode::render() like this:

Code: Select all

#define NUM_VERTICES 4
...
video::S3DVertex Vertices[NUM_VERTICES];
...
u16 indices[] = {0,2,1};
driver->drawIndexedTriangleList(&Vertices[0], NUM_VERTICES, &indices[0], 1);

I wonder wheter vertices[3] will be processed in the GPU. irrlicht only sets its color to glColor and calls glDrawElements, but I don´t know what happens then.

BTW: my triangle disapears when NUM_VERTICES is > 65536 (with 65536 it is shown).

[casty]

Ok, the 65536 limit is because there is a Maximal Primitive Count set to 65536.

[omaremad]

Irrlicht packs vertices into buffers before sending them to the gpu, this reduces the number of calls thus reducing the possiblity of the application becoming driver bound. and thus the lack of glvertex calls in the opengl driver source code.

Irrlicht can render over 65536 polygons without mods the polygons have to be in diffrent buffers. Its due to the integer variable that holds the numbers for the verts is a 32 bit one and thus has a 65536 limit a 64 bit one has double that limit.

[hybrid]

It's the variable that holds the indices which point to vertices, and this is short int which makes it hold at most 65535, int would fix it to over 2 billion vertices. This is found under the topic 32bit patch.

[needforhint]

indexing verticies with a 64bit number gives you limit for verticies 65536*65536

[Saturn]

Actually it is 65536*65536*65536*65536.
65536*65536 is 32bit.

[needforhint]

no , I got it right

[hybrid]

No, saturn is right. 65535 is 2^16. 65535*65535=2^16*2^16=2^(16+16)=2^32
You can easily derive 2^64 for the value saturn gave.

[EmmanuelD]

no , I got it right

2^64
= (2^32)*(2^32)
= (2^16)*(2^16)*(2^16)*(2^16)
= 65536*65536*65536*65536

So far, Saturn is right.

[needforhint]

gee, I thought 65536 = 2^36.
Wow, 65536*65536*65536*65536 that's some amount of verticies to have