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Offline Streetwalrus

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #360 on: July 05, 2014, 03:44:47 pm »
Nice ! But what is that glass pane for ? :P

Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #361 on: July 05, 2014, 03:48:01 pm »
It's purpose is to show you which block you're looking at currently. I'm very bad at drawing, but good at avoiding work and thus reusing other's :P
« Last Edit: July 05, 2014, 03:53:47 pm by Vogtinator »

Offline Streetwalrus

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #362 on: July 05, 2014, 03:52:26 pm »
Oh ok lol. XD

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #363 on: July 05, 2014, 07:39:15 pm »
Thats a very nice bush you've got there :P
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Offline willrandship

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #364 on: July 06, 2014, 01:14:09 am »
I'm curious: With nGL, would it be faster to render a variable-resolution texture in front of the camera than, say, doing a nearest-neighbor scaling in a 2D lib? I mean, all the GL will slow things down a bit, but the optimizations for texture handling may help make up for it. It would also allow for some effects that wouldn't be possible in 2D environments, and would allow you to restrict colorspaces as well.

Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #365 on: July 06, 2014, 08:58:30 am »
nGL renders only triangles, so is much more flexible in drawing textures at an arbitrary scale, rotation, translation etc., but that comes at the cost of:
  • Clipping
  • Culling
  • Z-Buffer
  • Interpolation along X and Y-Axis (With textures: 3 divisions per scanline, without: 1)
which wouldn't be necessary for simple 2D stuff. That's also the reason I wrote a basically seperate lib "texturetools.cpp" to do 2d transformations (basically blitting, scaling, font etc.) on TEXTUREs. And yes, it's faster than n2dlib ;)
« Last Edit: July 06, 2014, 09:22:32 am by Vogtinator »

Offline Hayleia

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #366 on: July 06, 2014, 09:54:33 am »
nGL renders only triangles, so is much more flexible in drawing textures at an arbitrary scale, rotation, translation etc., but that comes at the cost of:
  • Clipping
  • Culling
  • Z-Buffer
  • Interpolation along X and Y-Axis (With textures: 3 divisions per scanline, without: 1)
which wouldn't be necessary for simple 2D stuff. That's also the reason I wrote a basically seperate lib "texturetools.cpp" to do 2d transformations (basically blitting, scaling, font etc.) on TEXTUREs. And yes, it's faster than n2dlib ;)
Well I personnally didn't know about your 2D lib until recently (after n2Dlib was started) but you should definitely have bragged :P told about it sooner. The goal of n2Dlib was not to make something new, just to make a lib that runs at the same speed on CXes and non-CXes (and also that used the same format for "sprites" as nSDL). And apparently, not only it's slower on CXes but it's not even fast on the fastest model -.-
So could you share a link to your 2D lib and to a documentation about it ?
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Offline Streetwalrus

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #367 on: July 06, 2014, 09:56:07 am »
nGL renders only triangles, so is much more flexible in drawing textures at an arbitrary scale, rotation, translation etc., but that comes at the cost of:
  • Clipping
  • Culling
  • Z-Buffer
  • Interpolation along X and Y-Axis (With textures: 3 divisions per scanline, without: 1)
which wouldn't be necessary for simple 2D stuff. That's also the reason I wrote a basically seperate lib "texturetools.cpp" to do 2d transformations (basically blitting, scaling, font etc.) on TEXTUREs. And yes, it's faster than n2dlib ;)
Well I personnally didn't know about your 2D lib until recently (after n2Dlib was started) but you should definitely have bragged :P told about it sooner. The goal of n2Dlib was not to make something new, just to make a lib that runs at the same speed on CXes and non-CXes (and also that used the same format for "sprites" as nSDL). And apparently, not only it's slower on CXes but it's not even fast on the fastest model -.-
So could you share a link to your 2D lib and to a documentation about it ?
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Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #368 on: July 06, 2014, 10:11:35 am »
Well, it only does crafti-relevant parts, so no 2d primitives, just texture operations, but the header files should be enough documentation:
texturetools.h
font.h

Small example:
Code: [Select]
#include <libndls.h>

#include "texturetools.h"
#include "font.h"

int main()
{
    TEXTURE *screen = newTexture(SCREEN_WIDTH, SCREEN_HEIGHT);
    nglInit();
    nglSetBuffer(screen->bitmap);
    while(!isKeyPressed(KEY_NSPIRE_ESC))
    {
        //Draw
        glColor3f(0, 0, 0);
        glClear(GL_COLOR_BUFFER_BIT);

        drawString("Hi!\nThis is a small test!", 0xFFFF, *screen, 0, 0);

        nglDisplay();
    }
    nglUninit();
    deleteTexture(screen);
}

Edit: Forgot to #include <libndls.h>
« Last Edit: July 06, 2014, 03:14:33 pm by Vogtinator »

Offline Matrefeytontias

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #369 on: July 06, 2014, 10:20:29 am »
Okay so stop saying texturetools is faster than n2DLib : I just looked at your drawTexture routine, it's exactly the same as n2DLib's drawSprite. Also, in drawTextureOverlay (which is n2DLib's drawSpritePart equivalent) you do calculation for every pixel where I only do calculation once per call - so n2DLib is faster. I didn't dig up more than this for now.

EDIT : nevermind the statement about drawTextureOverlay, it's not what it does.
« Last Edit: July 06, 2014, 10:25:18 am by Matrefeytontias »

Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #370 on: July 06, 2014, 01:58:34 pm »
Quote
Okay so stop saying texturetools is faster than n2DLib : I just looked at your drawTexture routine, it's exactly the same as n2DLib's drawSprite
It isn't (probably a typo, but drawTexture = drawSpritePart). I know, I probably sound like an asshole now (:-\), but I already told you how you could optimize it:
  • Compile flags! With -Os gcc won't inline most functions etc.
  • Multiple unnecessary checks, e.g. "x < 320 && y < 240"
  • Unnecessary calculations per pixel, although you could do "c = ~c" once for each sprite
  • getPixel and setPixel are unnecessary
  • Too many branches. You should now that branches are the slowest thing ever on the nspire.
  • Const correctness for pointer variables, e.g.
    void drawSpritePart(unsigned short *src, unsigned int _x, unsigned int _y, Rect* part).
    Otherwise part can't be cached by the caller
  • Various micro-optimizations gcc doesn't do somehow :(
And there's still more to optimize. Partial loop unrolling as 2x16bit access is slower than 1x32bit for example.

To give you an example of a almost fully optimized function, I optimized drawTexture some more: https://github.com/Vogtinator/crafti/blob/master/texturetools.cpp#L151
GCC does some partial unrolling, but doesn't transform 2 16bit accesses (ldrh/strh) to 32bit access(ldr/str), although -Ofast should do something, should I report a bug?
Code: [Select]
    8e28: e15392b4 ldrh r9, [r3, #-36] ; 0xffffffdc
    8e2c: e14292b4 strh r9, [r2, #-36] ; 0xffffffdc
    8e30: e15392b2 ldrh r9, [r3, #-34] ; 0xffffffde
    8e34: e14292b2 strh r9, [r2, #-34] ; 0xffffffde

Some suggestions:
  • Use a Texture struct rather than a unsigned short* for better readability.
  • drawPolygon shouldn't use a va_list but rather the pointsList directly, for flexibility and performance
But now it's getting rather off-topic...

Edit: I didn't downvote you. I really like discussions both sides benefit from.
« Last Edit: July 06, 2014, 02:01:09 pm by Vogtinator »

Offline Hayleia

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #371 on: July 06, 2014, 02:05:34 pm »
  • Use a Texture struct rather than a unsigned short* for better readability.
Well, two of us come from Axe and care less about readability than about speed (even though it seems like we are not Nspire pros :P) or efficiency.

It isn't (probably a typo, but drawTexture = drawSpritePart). I know, I probably sound like an asshole now ( :/ ), but I already told you how you could optimize it.
Yes you are :P Not at all, on the contrary, as you said, you already told us how to improve, you are not just saying "you are stupid, I am the best" or something ;)
And thanks for telling again with a clear list, because iirc, last time you kind of briefly explained on IRC but not really clearly :)
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Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #372 on: July 06, 2014, 02:35:56 pm »
  • Use a Texture struct rather than a unsigned short* for better readability.
Well, two of us come from Axe and care less about readability than about speed (even though it seems like we are not Nspire pros :P ) or efficiency.
It should compile to the same code. If not, it could be faster due to alignment if you use a "flexible array member" (StackOverflow question)

Offline willrandship

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #373 on: July 06, 2014, 03:44:24 pm »
So, if you used the 2d lib, as it's still initiating an nGL screen, does that mean you could render a 2D backdrop on a 3D area? That would have some interesting potential.

Offline Vogtinator

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Re: nGL - a fast (enough) 3D engine for the nspire
« Reply #374 on: July 06, 2014, 04:08:00 pm »
Jup, I wanted to nGL to be as flexible as possible, but without neglecting performance.
I actually thought about rendering the block list to a TEXTURE and letting it "fly in" from up front. I could also render the inventory/quick-select to a ribbon in circle shape (forgot the word) and rotate it so that the currently selected slot points towards the cam (or in a \_/ shape, viewed from above)
The opposite direction is possible as well, e.g. mirrors, portals, side-by-side view - but I don't know how to integrate it into crafti easily.