#151207 - BovineFury - Wed Feb 20, 2008 11:57 pm
I'm trying to make a group of textured quads that can be lit via a display list (glCallList()). How is it done? I've been trying to find some explanation of how this works, searched the forum, etc.
Is there anywhere I can go to find a tutorial on how this works? I've checked the devkitpro examples, but all it has is how to do a triangle with no normal or texturing.
I can't use a exporter because the list has to be generated in play.
#151208 - nce - Thu Feb 21, 2008 12:23 am
As soon as you have understood a to make a simple triangle with just position...
all other info works the same way you push vertices on your list. You can push normal and texture uvs too....
( you can even push your texture binding )
_________________
-jerome-
#151209 - BovineFury - Thu Feb 21, 2008 12:33 am
Is there any specific order that things are supposed to be pushed? Normal before texture, etc?
#151210 - BovineFury - Thu Feb 21, 2008 1:05 am
For that matter, is there anywhere that explains anything about how the display lists are set up?
From the devkit triangle example:
FIFO_COMMAND_PACK(FIFO_BEGIN, FIFO_COLOR, FIFO_VERTEX16, FIFO_COLOR). I see two color commands. Why?
Partway through the list is
FIFO_COMMAND_PACK(FIFO_VERTEX16, FIFO_COLOR, FIFO_VERTEX16, FIFO_END)
Why?
I've been running google searches and coming up with 4-5 results, none of which are any help. Is there any documentation that explains any of this?
#151215 - M3d10n - Thu Feb 21, 2008 2:14 am
| BovineFury wrote: |
| For that matter, is there anywhere that explains anything about how the display lists are set up? |
Do a search for "display lists" on this forum and you should find a thread which has nice info about them (I don't have the link myself, but I learned most of it there). But I'll try to help.
A display list is a large array of u32's. You basically have 4 commands packed into a single u32, followed by the data for each command. Different commands need different amounts of data, or no data at all.
| BovineFury wrote: |
From the devkit triangle example:
FIFO_COMMAND_PACK(FIFO_BEGIN, FIFO_COLOR, FIFO_VERTEX16, FIFO_COLOR). I see two color commands. Why?
|
The macro FIFO_COMMAND_PACK() packs four u8 command IDs into a single u32 value. I'll translate that command sequence to immediate mode so you can read it better:
| Code: |
1 glBegin();
2 glColor();
3 glVertex3v16();
4 glColor();
|
When drawing each geometry vertex, the position (FIFO_VERTEX16 or glVertex3v16() call) is always the last one for each vertex, so lines 2 and 3 in the example above define the first vertex. The 2nd glColor() command will be applied to the next vertex.
| BovineFury wrote: |
Partway through the list is
FIFO_COMMAND_PACK(FIFO_VERTEX16, FIFO_COLOR, FIFO_VERTEX16, FIFO_END)
Why? |
Continuing from the previous commands...
| Code: |
5 glVertex3v16();
6 glColor();
7 glVertex3v16();
8 glEnd();
|
Line 5 ends the declaration of the 2nd vertex, then we have the 3rd vertex declared by lines 6 and 7. Line 8 closes the triangle.
Notice I didn't specify any parameters in the examples above. The command data is specified after the packed command. Here's a complete example:
| Code: |
u32 triangle[] =
{
12,
FIFO_COMMAND_PACK(FIFO_BEGIN, FIFO_COLOR, FIFO_VERTEX16, FIFO_COLOR),
GL_TRIANGLE,
RGB15(31,0,0),
VERTEX_PACK(inttov16(-1),inttov16(-1)), VERTEX_PACK(0,0),
RGB15(0,31,0),
FIFO_COMMAND_PACK(FIFO_VERTEX16, FIFO_COLOR, FIFO_VERTEX16, FIFO_END),
VERTEX_PACK(inttov16(1),inttov16(-1)), VERTEX_PACK(0,0),
RGB15(0,0,31),
VERTEX_PACK(inttov16(0),inttov16(1)), VERTEX_PACK(0,0),
}; |
This commands are executed in the following order:
| Code: |
FIFO_BEGIN
FIFO_COLOR
FIFO_VERTEX16
FIFO_COLOR
FIFO_VERTEX16
FIFO_COLOR
FIFO_VERTEX16
FIFO_END
|
Using immediate mode, it would look like this:
| Code: |
glBegin(GL_TRIANGLE);
glColor(RGB15(31,0,0));
glVertex3v16(inttov16(-1),inttov16(-1),0);
glColor(RGB15(0,31,0));
glVertex3v16(inttov16(1),inttov16(-1),0);
glColor(RGB15(0,0,31));
glVertex3v16(inttov16(0),inttov16(1),0);
glEnd();
|
The confusing thing is that FIFO_VERTEX16 needs two data entries (you can only fit two 16-bit coordinates in a u32), while all other commands in the example only require one. That's why there are always two VERTEX_PACK() calls next to each other: the first one defines the X and Y coordinates, and the 3rd one defines the Z coordinate (I'm not sure you can also set the W coordinate - never tested it).
Notice that the FIFO_END command has no data. When you understand that each command needs a different number of u32 data fields to work, dealing with display lists becomes much easier.
#151245 - BovineFury - Thu Feb 21, 2008 10:17 pm
Thank you. That was exactly what I needed to know. Texturing and normals are up and running.
#151255 - nce - Fri Feb 22, 2008 12:37 am
I've learn a lot when I started my exporter from 3dsmax in reading this :
http://nocash.emubase.de/gbatek.htm#ds3doverview
Geometry Commands (can be invoked by Port Address, or by Command ID) is the list of command you can use ( not all are working in display list I think ), and the number of parameter you'll have to send after.
and
http://nocash.emubase.de/gbatek.htm#ds3dgeometrycommands
explain you how to build a display list ( unpacked or packed as in the ndslib exemple )
_________________
-jerome-