OpenGL and Vertex Arrays

[Polo]

I hear the Vertex Arrays were a lot much faster, so I want to use them, with Purebasic of course, but I don't know really how... Does someone know how to ?

PS : Please don't link me to a tutorial page with C++ code

[traumatic]

I hear the Vertex Arrays were a lot much faster[...]

IMHO that's not always the truth. Sometime displaylists win, sometimes vertexarrays are faster. I think it depends on what you're trying to do.

PS : Please don't link me to a tutorial page with C++ code

No tutorial? Fine...

You can do it exactly like in C, here's a small code example, called the obligatory "RenderMeACubeAndMakeMeHappyExample"

Code: Select all

Dim vertices.f(23)
Dim indices.b(23)

Restore vertices
For i=0 To 23
  Read vertex.f
  vertices(i) = vertex
Next

Restore indices
For i=0 To 23
  Read index.b
  indices(i) = index
Next

DataSection
  vertices:
    Data.f -1.0,  1.0,  1.0
    Data.f  1.0,  1.0,  1.0
    Data.f  1.0, -1.0,  1.0
    Data.f -1.0, -1.0,  1.0
    Data.f -1.0,  1.0, -1.0
    Data.f  1.0,  1.0, -1.0
    Data.f  1.0, -1.0, -1.0
    Data.f -1.0, -1.0, -1.0

  indices:
    Data.b 0, 1, 2, 3
    Data.b 4, 5, 1, 0
    Data.b 3, 2, 6, 7
    Data.b 5, 4, 7, 6
    Data.b 1, 5, 6, 2
    Data.b 4, 0, 3, 7
EndDataSection

Later, you can render it like this:

Code: Select all

glEnableClientState_(#GL_VERTEX_ARRAY)
glVertexPointer_(3, #GL_FLOAT, 0, vertices())
glDrawElements_(#GL_QUADS, 24, #GL_UNSIGNED_BYTE, indices())

Voilá... no tutorial

[Dare2]

lol @ "renderMeACubeAndMakeMeHappy"

What values are #GL_VERTEX_ARRAY, #GL_FLOAT, #GL_QUADS, #GL_UNSIGNED_BYTE ?

And is there a tutorial for beginners explaining vertices and indices? Or life, the universe and everything?

[Rings]

And is there a tutorial for beginners explaining vertices and indices? Or life, the universe and everything?

42

[traumatic]

What values are #GL_VERTEX_ARRAY, #GL_FLOAT, #GL_QUADS, #GL_UNSIGNED_BYTE ?

They are defined in the opengl include.

And is there a tutorial for beginners explaining vertices and indices? Or life, the universe and everything?

Well, just take your favourite searchengine. There are a lot of tutorials on this.
OpenGL-related I can't recommend http://nehe.gamedev.net often enough. The OGL-Redbook (http://www.opengl.org)
also explains some basics of 3d, like the things you were asking for.

Other than that, I guess the best way to learn this kind of stuff is to read lots of books and to try.

Feel free to contact me on further questions.

And yes, 42...

[Dare2]

Ah 42!

Well, so long, and thanks for all the fishes.

[Polo]

instead of putting the vertices in arrays, can we put the vertices in memory ? If yes, how ?

[pg]

If they are in arrays they are allready in memory, you could access the memory location like this

address.l = @myarray(0).

or you can reserve memory

memaddress.l = AllocateMemory(0, size, 0)

and write to memory

PokeF(memaddress, vertex) // float values

and read
value.f=PeekF(memaddress)

for each new value you must increment the memoryaddress


you can test it with this code:

memaddress.l = AllocateMemory(0, 100, 0)
PokeF(memaddress, 125.23)
value.f=PeekF(memaddress)
MessageRequester("value read from memory: ", StrF(value), 0);

[Polo]

Thanks for the reply !
But that's not what I mean, I know how to use the memory, I mean, instead of putting :
glVertexPointer_(3, #GL_FLOAT, 0, vertices())
vertices is a Dim array, and I want to know if we can use the memory for that, if I use your example :

memaddress.l = AllocateMemory(0, 100, 0)
PokeF(memaddress, 125.23)
PokeF(memaddress+4, 125.23)
PokeF(memaddress+8, 125.23)

[...]

;and....

glVertexPointer_(3, #GL_FLOAT, 0, memaddress.l)

Well, perhaps not like that, but you see what I mean ?

[pg]

sorry, I see....

I think this must work, it's just a memory address



void glVertexPointer(GLint size,
GLenum type,
GLsizei stride,
const GLvoid *pointer)

pointer Specifies a pointer to the first coordinate of the first vertex in the array

[pg]

something like this if the first data is at 0...

glVertexPointer_(3, #GL_FLOAT, 0, @vertices(0))

[Polo]

I can't put @vertices(0) if I'm using memory...

[pg]

Yes, I did reboot my brain

that how I would do it, maybe you too?

Restore vertices
add.w=0
For i=0 To 23
Read vertex.f
PokeF(memaddress+add, vertex)
add=add+4
Next

[Polo]

I do that : I have one memory with the vertices, one with the indexes. The fact is I want to use these stuffs which are in memory, and that I don't know how to do...

[RonStyle]

Display lists will probably be alot faster than anything held in local sys-mem.(Depending on your card, display lists are usually stored within AGP memory, which is ddr on decent cards, and much closer to the gpu)

not to mention encapsulating everything needed to render the model in one ultra-tiday call.(Obviously not the reason to use it, but a nice side-effect )