Project: 3D Text / PSPGL

Arwin · Post by **Arwin** » Wed May 31, 2006 3:02 am

Hi guys,

Because I want to learn how to do 3D programming, I thought I would start with something that could be useful for other stuff later on, and is fun to do - build a low-poly text renderer.

Right now, I've just designed my own font that consists of no more than five triangles for each (capital) letter - using the form of the triangle to make an Asian style font that looks kinda fun.

Each of these can be scaled both width and height, and the width of the end of the triangle can also be specified to adjust the weight of the font. Currently, it works like this:

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	gltext_Param myGLChar;

	myGLChar.x = 0.0f;
	myGLChar.y = 0.0f;
	myGLChar.z = 0.0f;
	myGLChar.height = 1.0f;
	myGLChar.width = 0.5f;
	myGLChar.Red = 0.0f;
	myGLChar.Green = 0.0f;
	myGLChar.Blue = 0.0f;
	myGLChar.endwidth = 0.1f;
	myGLChar.unicodechar = 65;

                DrawGLChar&#40;&myGLChar&#41;;

And you can write text for it using this:

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int i=0;
	while&#40;myText&#91;i&#93; != '\0'&#41;
	&#123;

		myGLChar.unicodechar = myText&#91;i&#93;;
		myGLChar.x = i*&#40;0.6f*zoom&#41;;
		i++;
		DrawGLChar&#40;&myGLChar&#41;;
	&#125;

Here's an .elf sample. I'll post source as soon as I made it a proper library and add 0-9 and dots 'n stuff.

Once Display Lists are working (and I've learnt how to use them), I could imagine making a function that returns the display list merge data rather than draw the stuff right away as it does now.

If anyone is interested in having this do certain things so that they could make use of it somehow, or has other kinds of input, let me know.

Arwin · Post by **Arwin** » Thu Jun 01, 2006 2:32 am

By the way, I would like to make this into something using the sceGu directly. If someone has an example of how to draw just one triangle, no textures, that would be great.

I edited the textured cube example, and just by removing everyting that refers to texture, I either get a completely garbled cube, or a fog that blocks everything, and really don't understand how. : blush :

LuMo · Post by **LuMo** » Sun Jun 04, 2006 1:40 am

sorry to refer to my own work.
you can model your text in MAYA and export it (with my homebrewn export script)

then translate it to my psp format (.3db)

then load it to psp using my object loader (pspLoader)

betatesting is currently running! (although i only have ONE betatester)

IFF you want you can be my second beta tester!
what does this mean?
you get the full source code before official release (which should be soon...)
you need to test my stuff and report me bugs/problems
you need maya to export models!

greets
lumo

PS: defining models in source code might work too, but... it would kill me ;)

Arwin · Post by **Arwin** » Sun Jun 04, 2006 11:18 am

I am interested, I will send you my email! I will also try to post my initial source tomorrow ...

Arwin · Post by **Arwin** » Wed Jul 05, 2006 11:42 pm

I have played with this some more, and have added numbers, a few marks.

I have also added support for variable width type setting. For this, I added an extra property that reports the actual width that the character has been drawn at.

I also came across this: http://homepages.paradise.net.nz/henryj/code/#FTGL

This looks like an interesting project to try to port. Don't know if there are any takers ... if not, I may have a go at it after I've finished playing around with the current project.

The upside of my project is that it uses a minimum of polys and it will be the only include necessary and no extra libraries, font files, and so on. That's what I am aiming for - if only, it will be something that will ease debugging and such. But it's also fun to play around with some animation and effects stuff.

I'll try to post the first source code soon so others can play around with it.

Arwin · Post by **Arwin** » Thu Jul 06, 2006 9:50 am

Ok, here's the rough code, a sample PSPGL targeting main.c (heavily borrowing from the ported NeHe sample lesson 6, I didn't even remove the texture yet) that implements gltextlight through header file, all included.

Here's the link: http://www.niwra.nl/psp/gltextlight/gltextlight.rar

And here's a little screenshot, to give an impression:

dot_blank · Post by **dot_blank** » Thu Jul 06, 2006 3:48 pm

really cool buddy

Arwin · Post by **Arwin** » Fri Jul 07, 2006 2:48 am

dot_blank wrote:really cool buddy

Thanks. :)

Now hopefully we can make some fun things with this.

Also, optimisation ideas are very welcome. Though I suspect to have optimisations under PSPGL an important factor is probably going to be to have display lists of some sort.

Raphael · Post by **Raphael** » Fri Jul 07, 2006 4:44 pm

Nice Idea there with the poly-glyphs :)

Though I'd probably use a structure array to hold the vertice data for each character and in the drawing function just would render it from there. That would make it much more cleaner, rather than having 100's of switch cases. Sizing could be done by a scale matrix call.
But that's just how I would aproach something like that.

For optimisations I would suggest you try with direct sceGu function calls first, though I'm not sure about how much that would gain (haven't had a look at how efficiently pspgl wraps those calls). The most effective speed improvement would probably be a glyph cache though. Render your string into an offscreen texture and then just do a single texture quad on the screen (This way, you could also get some antialiasing effect done, by doing a downsample of the offscreen texture before rendering.

Well, keep up :)

Arwin · Post by **Arwin** » Fri Jul 07, 2006 6:11 pm

Raphael wrote:Nice Idea there with the poly-glyphs :)

Though I'd probably use a structure array to hold the vertice data for each character and in the drawing function just would render it from there. That would make it much more cleaner, rather than having 100's of switch cases. Sizing could be done by a scale matrix call.
But that's just how I would aproach something like that.

Yeah, that sounds much better. So far it has been easy developing the glyphs like this, but it shouldn't be much harder to do it from an array. I'm just not yet well versed enough in this language to be comfortable doing so yet. For example, when I thought about it initially, I couldn't immediately figure out how to deal with different amounts of triangles for the glyphs. I suppose I need an array of character structures, which in turn has a property with an index value of where in the coordinates array this character starts, and then have something in that array which marks the end of this glyph's coordinate?

For optimisations I would suggest you try with direct sceGu function calls first, though I'm not sure about how much that would gain (haven't had a look at how efficiently pspgl wraps those calls).

I will probably stick with PSPGL as long as I can, because it's a great luxury to be able to so easily develop on PC and then port that code.

The most effective speed improvement would probably be a glyph cache though. Render your string into an offscreen texture and then just do a single texture quad on the screen (This way, you could also get some antialiasing effect done, by doing a downsample of the offscreen texture before rendering.

Yes, but I'm taking that as something on a different abstraction level. I would write a different library which works like that ... but for now I am more interested in creating stuff that is (part of) a 3D environment.

Well, keep up :)

Thanks! I just created a kind of text vortex, which is a lot of fun. That's the kind of thing I was looking for doing. I originally wanted to create some word games which use 3D text.

I discovered a little bug in the drawing of the U character, btw, I'll have a fixed upload soon in case anyone noticed.

Arwin · Post by **Arwin** » Fri Jul 07, 2006 10:00 pm

Small fixed version updated, now with a spiral like textflow ... I also draw the letters double real close with the second one a light color as a test for seeing if this can achieve rudimentary AA. It looks like it might (at least, from the right angle of course). Will have to test with letters viewed from the front to see how that works out.

Raphael · Post by **Raphael** » Fri Jul 07, 2006 10:26 pm

Arwin wrote: Yeah, that sounds much better. So far it has been easy developing the glyphs like this, but it shouldn't be much harder to do it from an array. I'm just not yet well versed enough in this language to be comfortable doing so yet. For example, when I thought about it initially, I couldn't immediately figure out how to deal with different amounts of triangles for the glyphs. I suppose I need an array of character structures, which in turn has a property with an index value of where in the coordinates array this character starts, and then have something in that array which marks the end of this glyph's coordinate?

Well, in your case that really isn't that trivial to achieve, since you have an array of variable length arrays. Easiest way would be to declare a structure with a fixed number of triangles and in the
definition, just fill unneeded tris with 0's.

abstracted simplified approach:

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struct nlist &#123;
int n_items;
int item&#91;4&#93;;
&#125;;

struct nlist mylist&#91;&#93; = &#123; &#123; 3, &#123; 1, 2, 3, 0 &#125; &#125;, // list entry 1 consisting of 3 items
&#123; 2, &#123; 2, 6, 0, 0 &#125; &#125;, // list entry 2 consisting of 2 items
... &#125;;

In your case, nlist would be the structure for one glyph, n_items would be the number of triangles and each item[] would be a triangle, made up of three vertices (or just vertice indices) instead of a single int.
You could possibly also skip the n_items, if you define one case of a triangle structure as the 'NULL' triangle (in the above case it could be simply 0, for your case probably a triangle made of three 0-indices) and decide by that when there aren't any more triangles.

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#define MAX_TRIS 4
struct tri &#123;
int verts&#91;3&#93;;
&#125;;

struct glyph &#123;
struct tri tris&#91;MAX_TRIS&#93;;
&#125;;

struct glyph glyphs&#91;&#93; = &#123; &#123;&#123; &#123;1,2,3&#125;, &#123;3,4,5&#125;,&#123;6,7,8&#125;,&#123;&#123;0&#125;&#125; &#125;&#125;, // glyph 1, 3 tris
&#123;&#123; &#123;3,5,8&#125;, &#123;9,12,11&#125;, &#123;&#123;0&#125;&#125;, &#123;&#123;0&#125;&#125; &#125;&#125;, // glyph 2, 2 tris
 &#123; &#123;0&#125; &#125; // null-glyph &#125;;

Would be better readable if I did proper indenting with tabs.
Looking at all that, maybe your approach wasn't that bad at all ;P

Yes, but I'm taking that as something on a different abstraction level. I would write a different library which works like that ... but for now I am more interested in creating stuff that is (part of) a 3D environment.

That's up to your decision how far your abstraction level goes :) But since you only provide the raw code for drawing single chars it's pretty low-level, so its ok to stay away from complicating caching algorithms :)
[/u]

Arwin · Post by **Arwin** » Fri Jul 07, 2006 11:08 pm

i guess for the moment I will stay with the current setup then. ;)

But if I would do it, I would create one index array linked to characters, i.e.:

e[charcode]=index_to_location_in_vertices_array

drawFromList(list_index) as drawnWidth

It could quickly get complicated though. I would have to define / figure out what part of the vertices array is what - i.e., which part should be scaled in what way for width, endwidth, height, and so on.

I'll keep muddling like I have now for a slight bit more I think. ;)

I notice that it is much, much harder to create something that is readable when drawn small. I think for now that will actually be too hard, though I can improve readability here and there by making lines rectangular rather than triangular. I think I will experiment with that a bit in a second draw function, but perhaps I should try to make do with what i have now and play with some larger letters instead. ;)