Bitmap2Mesh (release v3.0)

An article by mgear    16 Comments

Bitmap to 3D Extruded Mesh-script. Related to this forum topic (unity forum link)

What it is?
It reads bitmap pixel by pixel, checks if pixel alpha value is > 0, then add vertice there (but skip adding, if we are going the same direction) (it follows the shape border, currently just 1 shape is scanned..)

Then it uses Triangulator from unifywiki and This extrude script from unity forums to make it 3D.*
*Re-wrote the extrusion connection, now its using Unity Examples Procedural-extrusion. (which can be also used to extrude in multiple sections)

TODO:
– Optimization, clean up (or dont add) too many vertices, if its a straight line (done, using kind of “RLE”)
– UV mapping.. problem if you try to add textures to this version (Planar UV map works, not sure how to make others, * Testing Custom UV mapping, works bit better)
– Some error checking, havent tried yet what happens if you make multiple objects in the bitmap..or holes..? (It only detects the first object that it hits, when scanning pixels)
– Pivot location (see update note #2)
– Scaling (currently its 1pixel = 1unit..) (see update note #2)
– Last vertice / triangle /uv is sometimes broken? (hopefully fixed, 1.2.2012, see update note #1)
– Model is mirrored / upside down?
– Proper UV mapping / texturing (bake vertex colors? special shader: 2 materials, use vertex color as mask?)
– Support multiple shapes (submeshes, combine meshes?)
– Use bitmap image as texture directly (possible after proper UV’s are done?) (works, just need to remove extra variable..)
– Fix scanning: breaks if there is not atleast 1 pixel empty margin around the image.. (done)
– Cannot scan diagonal pixels or too thin lines.. (Now works)
– Single pixels coming out from the shape are not correctly square (need to add extra vertex function there later..)
– Need to do scaling for gameObject, instead of pixels..(?)
– Make the whole thing as a function/class.. so you can call it and pass the bitmap image, settings  as a variables

FUTURE IDEAS:
– Make pixel texture painter script, so you can paint your weapon and click “extrude to 3D” (test version done, not so useful yet..)
– Take extrude depth from alpha or color value? So you could make it a bit less blocky?
– Bake texture to vertex colors? (would need more vertices..?)
– Make it as unity editor script?
– Make it as online page (you draw / upload bitmap, it creates you the mesh to download, as .obj or …)

*Update#1 (1.2.2012)
This fixed the uv/triangle problem in some cases,
Find these 2 lines:

triangles[count_tris+4] = n + poly.Length;
triangles[count_tris+5] = i + poly.Length;

replace with these 2 lines: (swaps 4 and 5)

triangles[count_tris+5] = n + poly.Length;
triangles[count_tris+4] = i + poly.Length;

*Update#2 (2.2.2012)
If you want to set pivot point to first encountered pixel(vertex)
and to set the scale (currently 1 pixel = 1 unit), do it here:

Find line:

polys.Push(scanpoint);

Replace with: (you could make the “0.1” (=pixelscale) as public variable, so you can easily adjust it later

polys.Push((scanpoint-startpoint)*0.1);

*Update#2 (4.2.2012)
Custom UV mapping & texturing.. (see image#3)
need to clean it up a bit and do testing before upload..

*Update#3 (5.2.2012)
Updated the pixel scanning system, now its more robust and takes the outer edge of pixel as vertex location (not the pixel midpoint..)
See image#4, original minecraft sword extruded & textured.
Added v2 download for testing..

*Update#4 (9.2.2012)
Now UV mapping works on most cases
Added v3 download link to the toolbar

Download source: (js + c#)

mBitmapToMesh,unitypackage  v1.0
mBitmap2Meshv20,unitypackage  v2.0
mBitmap2Meshv30.unityPackage v3.0

Additional images:
Image#2: Optimized vertices (compare to the main image)

Image#3: Automatic UV mapping and texturing (using the original bitmap).. bit off, but close enough for now..

—
Image#4: Original minecraft sword .png, extruded to 3D (same image as texture) *Sword image  © Mojang/Minecraft
(Sides still have UV mapping problems..)