Sign in to follow this  

Unity BSPv38 - Quake 2 BSP loader lightmap problem

This topic is 2330 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hey guys! I'm trying to write a quake 2 BSP loader, and everything works completely fine except for my lightmap...where I've come to a complete halt, much like this poor person: http://www.gamedev.net/community/forums/topic.asp?topic_id=17243 Is anyone floating around here thats run into the same problem? Half my lightmaps look good the other half of surfaces seem warped and retarded - like I've got the wrong dimensions or something. The general color of the lightmaps seem correct But I've followed http://www.flipcode.com/archives/Quake_2_BSP_File_Format.shtml and snooped around heaps, but I've only found people with the same problem, not solutions =( Here are comparison screenies: Here quake 2 screenshot with console command gl_lightmap 1: http://img523.imageshack.us/my.php?image=lightmap2.jpg Here is my engine's futil attempt at rendering the lightmap: (with tex filter turned off): http://img523.imageshack.us/my.php?image=lightmap1.jpg Also, it would be of great help if someone can point me to where quake 2 source stores each face's lightmap width/height, as I can just output that and compare. I've been digging through this q2source and keep getting lost o.O

Share this post


Link to post
Share on other sites
make sure you're using bilinear filtering on the lightmap textures, in opengl i think the functions are

glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);

Share this post


Link to post
Share on other sites
yes i can easily put bilinear filtering on,

except it still looks "wrong" for some reason - my texture width/height calculations seem off, but I've followed that guide EXACTLY.

I also don't understand the part about lightmap being max 16x16...I'm getting lightmaps that are much larger than 16x16 from the exact formula he has given on the site, the web page contradicts itself o.O

Thanks,
HyperNewbie

Share this post


Link to post
Share on other sites
Anyway, from looking at other people's projects and randomly modifying random bits of bitsy code, I somehow managed to get the formula right.

The formula for texture width and height are wrong, and the website has no mention of how lightmap texture coordinates are calculated.

I'll post my findings here, just in case anyone comes across this page on google with the exact same problem I ran into:

This info is for BSPv38, in other words Quake 2 BSP files, regarding lightmaps and loading and rendering them properly. I used openGL to do the rendering.

Getting lightmap dimensions:

Face structure gives the lightmap offset, but for some crazy reason, does not give the lightmap dimensions: you must calculate them yourself by going through every vertex, calculating their texture map U V co-ordinates and do stuff to them.

So, first, you go through every vertex of the face, and calculate their UV co-ordinates (use the formulae on the website http://www.flipcode.com/archives/Quake_2_BSP_File_Format.shtml).

u = x * u_axis.x + y * u_axis.y + z * u_axis.z + u_offset
v = x * v_axis.x + y * v_axis.y + z * v_axis.z + v_offset

Then, you get the results in two floats, u and v. FLOOR u and FLOOR v into two integers, floor_u and floor_v. Then, you check floor_u and floor_v against max_u and max_v and min_u and min_v (4 of them all integers), to get the maximum and minimum floor_u and floor_v variables seen so far. DO NOT GET MAXIMUM/MINIMUM u and v. We need maximum/minimum floor_u and floor_v.

Then, you divide the min_u and max_u and min_v and max_v variables by 16, in FLOAT. If you are using C++, this means you will need to specifically typecast those 4 ints into float before dividing by 16.

Then, you floor the two min_ variables and ceil the two max_ variables, get the difference between the two, add 1, and typecast the result back to an int.

Here is my little bit of C++ code that does this step:

_minU = (float)floor((float)(minU / 16.0));
_maxU = (float)ceil((float)(maxU / 16.0));
_minV = (float)floor((float)(minV / 16.0));
_maxV = (float)ceil((float)(maxV / 16.0));
LIGHTMAPW = (int)(_maxU - _minU + 1);
LIGHTMAPH = (int)(_maxV - _minV + 1);

Getting lightmap texture co-ordinates:
This will generate a texture co-ordinate that's in the range 0.0 to 1.0, for opengl glTexCoord2f usage.

Let's say we need to get the texture co-ordinates for a vertex.

we first calculate the u and v for the texture map, the formula given above.
Then, we get LIGHTMAPW and LIGHTMAPH , also given above
We also need the minU and minV and maxU and maxV from above, the max/min floor_u and floor_v for all vertexes.

Then, simply follow this formula:

float MidPolyU = (minU + maxU) / 2.0;
float MidPolyV = (minV + maxV) / 2.0;
float MidTexU = LIGHTMAPW / 2.0;
float MidTexV = LIGHTMAPH / 2.0;
float lightmap_u = MidTexU + (u - MidPolyU) / 16.0;
float lightmap_v = MidTexV + (v - MidPolyV) / 16.0;
glTexCoord2f(lightmap_u/LIGHTMAPW ,lightmap_v/LIGHTMAPH );

As you can see, we get the co-ordinates and make them relative to the middle of the texture. Or something like that.

Hopefully this will solve the problems for people who are trying to load quake2's BSP files and get stuck at trying to load the lightmaps, because nowhere on the face of the internet is there such a documentation of this and quake 2 source code takes a while to excavate into.

Check six,
HyperNewbie

Share this post


Link to post
Share on other sites
I know the topic is too old.
But I want to make the answer clear for others, because I spent a lot of time determining the source of wierd/broken/rainbow lightmaps.
So here is how to read lightmaps from quake 2 bsp file.
The next code is a bit simplified and there is no lightmap baking into one single texture here.
Only per-face generation of lightmaps just to be clear of all texture coordinate/dimensions calculations.

1. Just get all the data into memory:
[code]int lightmapDataLength = header.lump[LUMP_LIGHTMAPS].length; // /sizeof(unsigned char);
unsigned char lightmapData = new unsigned char[lightmapDataLength];
fseek(file, header.lump[LUMP_LIGHTMAPS].offset, SEEK_SET); // LUMP_LIGHTMAPS is 7
fread(lightmapData, sizeof(unsigned char), lightmapDataLength, file);[/code]
Alternatively you can also seek for each lightmap while iterating through bsp faces. Current lightmap for current face would be located at [i]header.lump[LUMP_LIGHTMAPS].offset + currentFace.lightmap_offset[/i]

2. Yes, to get lightmap dimensions you must process all faces and get those damn floored min/max of UVs.
First of all you must init the face data like this:
[code]faces[f].fminUV.x = 999999;
faces[f].fminUV.y = 999999;
faces[f].fmaxUV.x = -99999;
faces[f].fmaxUV.y = -99999;[/code]
Then, you calculate the texture coordinates exactly like it's written on all q2bsp specs:
[code]faces[f].texcoords[i*2 + j].x = verts[idx].x * texinfo->u_axis.x + verts[idx].y * texinfo->u_axis.y + verts[idx].z * texinfo->u_axis.z + texinfo->u_offset;
faces[f].texcoords[i*2 + j].y = verts[idx].x * texinfo->v_axis.x + verts[idx].y * texinfo->v_axis.y + verts[idx].z * texinfo->v_axis.z + texinfo->v_offset;[/code]
And only after that you compute min/max values while iterating through faces:
[code]
faces[f].fminUV.x = min(floor(faces[f].texcoords[i*2 + j].x), faces[f].fminUV.x);
faces[f].fminUV.y = min(floor(faces[f].texcoords[i*2 + j].y), faces[f].fminUV.y);
faces[f].fmaxUV.x = max(floor(faces[f].texcoords[i*2 + j].x), faces[f].fmaxUV.x);
faces[f].fmaxUV.y = max(floor(faces[f].texcoords[i*2 + j].y), faces[f].fmaxUV.y);[/code]

3. Now you're ready to get lightmap dimensions:
[code]int lightMapWidth = ceil(faces[f].fmaxUV.x/16) - floor(faces[f].fminUV.x/16) +1;
int lightMapHeight = ceil(faces[f].fmaxUV.y/16) - floor(faces[f].fminUV.y/16) +1;[/code]

4. Now the [b]important part[/b] which is still never indicated by anybody, with a little exceptions.
First of all if you choose to offset into lightmap data array directly, like:
[code]unsigned char *lm_data = &lightmapData[face->lightmap_offset];[/code]
And then pass rgb data into opengl you MUST specify alignment!
[code]glPixelStorei(GL_PACK_ALIGNMENT,1);
glPixelStorei(GL_UNPACK_ALIGNMENT,1);
glTexImage2D(GL_TEXTURE_2D, 0, 3, lightMapWidth, lightMapHeight, 0, GL_RGB, GL_UNSIGNED_BYTE, lm_data);[/code]
Without this all the people get lightmaps which are diagonaly projected or a lot of rainbow colors.
This deceives most developers and they think like: damn the calculations are wrong, there is something wrong with pointers/data/uvs/etc BUT ITS THE DAMN ALIGNMENT (blame Carmack for all this shit!)
The alternative way to read the data is to read it as rgb and add fourth component with value 255 and upload into rgba texture, like this:
[code]static unsigned char lm_data[32*32*4] = {0};
fseek(file, header.lump[LUMP_LIGHTMAPS].offset + face->lightmap_offset, SEEK_SET);
for(int y = 0; y<lightMapHeight; y++) {
for(int x = 0; x<lightMapWidth; x++) {
unsigned char rgba[4];
fread(rgba, sizeof(unsigned char), 3, file); // read rgb
rgba[3] = 255; // set the 4th component to 255
memcpy(&lm_data[x*4+(y*4)*lightMapWidth], rgba, sizeof(unsigned char)*4); // write as rgba
}
}
glTexImage2D(GL_TEXTURE_2D, 0, 4, lightMapWidth, lightMapHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, lm_data);[/code]
And don't forget the clamping:
[code]glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);[/code]

5. Rendering (resulting texture coordinates generation):
[code]u = face->texcoords[j].x;
v = face->texcoords[j].y;
u -= face->fminUV.x;
v -= face->fminUV.y;
u /= (face->fmaxUV.x - face->fminUV.x);
v /= (face->fmaxUV.y - face->fminUV.y);
glTexCoord2f(u, v);
glVertex3fv(&face->vertices[j].x);[/code]

The result... well not totally but almost identical.
[url="http://imageshack.us/photo/my-images/577/quake2vscustom.jpg/"][img]http://img577.imageshack.us/img577/7760/quake2vscustom.th.jpg[/img][/url]

Share this post


Link to post
Share on other sites
The other alternative is to study the GPL Quake 2 source code and see how that does it (by packing lightmap textures into a 128x128 atlas and adjusting texcoords to match so that alignment isn't actually a problem).

Share this post


Link to post
Share on other sites
[quote name='mhagain' timestamp='1311940732' post='4842103']
The other alternative is to study the GPL Quake 2 source code and see how that does it (by packing lightmap textures into a 128x128 atlas and adjusting texcoords to match so that alignment isn't actually a problem).
[/quote]
[center][img]http://demotivationals.co/demot/2010-09-24-09-13-15142648791.jpg[/img]
[left]srsly, did you try that yourself?
Why there's a tons of broken specs and such a clever person like you still didn't post any explanation anywhere so people won't be having problems?
Study what?...
A lot of non-commented retarded code with thousands of hax and funny comments like [i]'// sigh'[/i] or [i]'// stupid quake bug'[/i] where static lightmapping mixed with dynamic one with wrapped functions of memory allocation and also complicated with atlasing and hardware specific routines and around 80kb of code (gl_rsurf.c, gl_light.c, gl_model.c) just for this? LOL

Everyone knows that it does pack into atlas. But the alignment is an actual problem ANYWAY [b]even if you will use atlas[/b].
Why? Well, just try to upload lightmaps into your atlas having everything in GL_RGB (hell isn't obvious to use rgb when it's stored in rgb lol) format with TexSubImage and you'll get nice rainbows.
So there is a choice: you either store it in GL_RGBA filling dump alpha channel with 255 or using glPixelStorei with GL_RGB.
[i]It's not because lightmaps are not in atlas, it's because of how the data is stored in binary bsp file...[/i]

That's it and no need to 'study' any code where obvious things wrapped around thousand data structures.
I showed per-face texturing just because it's lot easier to understand. After this you can easily make atlas or whatever you want.
[/left] [/center]

Share this post


Link to post
Share on other sites
[quote name='gogiii' timestamp='1311943255' post='4842111']sly, did you try that yourself?[/quote]

As it happens, I did.

Yes - there is deep ugliness in there, but yes - if you want to work with Quake 2 formats then it is the definitive reference. Please note that I'm [i][b]not[/b][/i] sayig "copy/paste this code". What I'm saying is "if you want to know how lightmaps are supposed to work in the Quake 2 engine, this is the place to go".

Share this post


Link to post
Share on other sites

This topic is 2330 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

Sign in to follow this  

  • Forum Statistics

    • Total Topics
      628710
    • Total Posts
      2984331
  • Similar Content

    • By AndySv
        Total Music Collection (http://u3d.as/Pxo)   THE COLLECTION CONTAINS:   Mega Game Music Collection   Universal Music Collection   Huge library of high quality music for any project! All at an incredibly low price!   - 2,5GB of high quality audio - 100+ different music tracks - Loop and short versions   Action, fantasy, casual, horror, puzzle, epic, dramatic, romantic, positive, inspiring, motivational and more!
    • By Dafu
      FES Retro Game Framework is now available on the Unity Asset Store for your kind consideration!
      FES was born when I set out to start a retro pixel game project. I was looking around for an engine to try next. I tried a number of things, from GameMaker, to Fantasy Consoles, to MonoGame and Godot and then ended up back at Unity. Unity is just unbeatable in it's cross-platform support, and ease of deployment, but it sure as heck gets in the way of proper retro pixel games!
      So I poured over the Unity pipeline and found the lowest levels I could tie into and bring up a new retro game engine inside of Unity, but with a completely different source-code-only, classic game-loop retro blitting and bleeping API. Months of polishing and tweaking later I ended up with FES.
      Some FES features:
      Pixel perfect rendering RGB and Indexed color mode, with palette swapping support Primitive shape rendering, lines, rectangles, ellipses, pixels Multi-layered tilemaps with TMX file support Offscreen rendering Text rendering, with text alignment, overflow settings, and custom pixel font support Clipping Sound and Music APIs Simplified Input handling Wide pixel support (think Atari 2600) Post processing and transition effects, such as scanlines, screen wipes, screen shake, fade, pixelate and more Deploy to all Unity supported platforms I've put in lots of hours into a very detail documentation, you can flip through it here to get an better glimpse at the features and general overview: http://www.pixeltrollgames.com/fes/docs/index.html
      FES is carefully designed and well optimized (see live stress test demo below). Internally it uses batching, it chunks tilemaps, is careful about memory allocations, and tries to be smart about any heavy operations.
      Please have a quick look at the screenshots and live demos below and let me know what you think! I'd love to hear some opinions, feedback and questions!
      I hope I've tickled your retro feels!



      More images at: https://imgur.com/a/LFMAc
      Live demo feature reel: https://simmer.io/@Dafu/fes
      Live blitting stress test: https://simmer.io/@Dafu/fes-drawstress
      Unity Asset Store: https://www.assetstore.unity3d.com/#!/content/102064

      View full story
    • By Dafu
      FES Retro Game Framework is now available on the Unity Asset Store for your kind consideration!
      FES was born when I set out to start a retro pixel game project. I was looking around for an engine to try next. I tried a number of things, from GameMaker, to Fantasy Consoles, to MonoGame and Godot and then ended up back at Unity. Unity is just unbeatable in it's cross-platform support, and ease of deployment, but it sure as heck gets in the way of proper retro pixel games!
      So I poured over the Unity pipeline and found the lowest levels I could tie into and bring up a new retro game engine inside of Unity, but with a completely different source-code-only, classic game-loop retro blitting and bleeping API. Months of polishing and tweaking later I ended up with FES.
      Some FES features:
      Pixel perfect rendering RGB and Indexed color mode, with palette swapping support Primitive shape rendering, lines, rectangles, ellipses, pixels Multi-layered tilemaps with TMX file support Offscreen rendering Text rendering, with text alignment, overflow settings, and custom pixel font support Clipping Sound and Music APIs Simplified Input handling Wide pixel support (think Atari 2600) Post processing and transition effects, such as scanlines, screen wipes, screen shake, fade, pixelate and more Deploy to all Unity supported platforms I've put in lots of hours into a very detail documentation, you can flip through it here to get an better glimpse at the features and general overview: http://www.pixeltrollgames.com/fes/docs/index.html
      FES is carefully designed and well optimized (see live stress test demo below). Internally it uses batching, it chunks tilemaps, is careful about memory allocations, and tries to be smart about any heavy operations.
      Please have a quick look at the screenshots and live demos below and let me know what you think! I'd love to hear some opinions, feedback and questions!
      I hope I've tickled your retro feels!



      More images at: https://imgur.com/a/LFMAc
      Live demo feature reel: https://simmer.io/@Dafu/fes
      Live blitting stress test: https://simmer.io/@Dafu/fes-drawstress
      Unity Asset Store: https://www.assetstore.unity3d.com/#!/content/102064
    • By Dafu
      Hello all,
      I've been hard at work on a new retro pixel-perfect framework called FES Retro Game Framework. It is now available on the Unity Asset Store for your kind consideration!
      FES was born when I set out to start a retro pixel game project. I was looking around for an engine to try next. I tried a number of things, from GameMaker, to Fantasy Consoles, to MonoGame and Godot and then ended up back at Unity. Unity is just unbeatable in it's cross-platform support, and ease of deployment, but it sure as heck gets in the way of proper retro pixel games!
      So I poured over the Unity pipeline and found the lowest levels I could tie into and bring up a new retro game engine inside of Unity, but with a completely different source-code-only, classic game-loop retro blitting and bleeping API. Months of polishing and tweaking later I ended up with FES.
      Some FES features:
      Pixel perfect rendering RGB and Indexed color mode, with palette swapping support Primitive shape rendering, lines, rectangles, ellipses, pixels Multi-layered tilemaps with TMX file support Offscreen rendering Text rendering, with text alignment, overflow settings, and custom pixel font support Clipping Sound and Music APIs Simplified Input handling Wide pixel support (think Atari 2600) Post processing and transition effects, such as scanlines, screen wipes, screen shake, fade, pixelate and more Deploy to all Unity supported platforms I've put in lots of hours into a very detail documentation, you can flip through it here to get an better glimpse at the features and general overview: http://www.pixeltrollgames.com/fes/docs/index.html
      FES is carefully designed and well optimized (see live stress test demo below). Internally it uses batching, it chunks tilemaps, is careful about memory allocations, and tries to be smart about any heavy operations.
      Please have a quick look at the screenshots and live demos below and let me know what you think! I'd love to hear some opinions, feedback and questions!
      I hope I've tickled your retro feels!



      More images at: https://imgur.com/a/LFMAc
      Live demo feature reel: https://simmer.io/@Dafu/fes
      Live blitting stress test: https://simmer.io/@Dafu/fes-drawstress
      My own game I started working on using FES, a roguelike, very early: https://simmer.io/@Dafu/merl
      Unity Asset Store: https://www.assetstore.unity3d.com/#!/content/102064
       
       
    • By Apollo Cabrera
      Yasss!!! My first Unity3d game is on the App Store and Google Play.
      Download please! About 30 minutes to get through 5 missions.
      Let me know what you guys think.
      Thanks a bunch
       
  • Popular Now