Back to posts.

Blender 2.8 OpenGL Buffer Exporter

Recently I needed to create a test case while integrating the Google Filament library into my engine. For this test case I wanted to get the vertices from the selected object in Blender, into a buffer that I could render with OpenGL.

The following Blender script creates a [name].h and [name].cpp for the selected object and stores the positions, normals and UVs. Note that this is a very basic script with a minimal amount of error checking.

# roxlu - 2019-08-04 - Blender 2.8
# ------------------------------------------------
# Very basic script that exports the vertices of the selected object
# to a .h and .cpp that you can use into your graphics app directly.
# Vertices are rotated to Y-up, -Z forward, following common OpenGL.
#
#
# Version:
# ------------------------------------------------
# v0.0.0  - 2019-08-04:   First release 
#
# Reference:
# ------------------------------------------------
# http://roxlu.com/2019/061/blender-2-8-opengl-buffer-exporter
# http://roxlu.com/2012/001/export-blender-object-to-simple-file-format
 
import bpy
import math
import mathutils
from mathutils import Vector, Matrix
 
o = bpy.context.active_object
output_vertices = []
output_indices = []
mat_x90 = mathutils.Matrix.Rotation(-math.pi/2, 4, 'X')
conv_mat = o.matrix_world
depsgraph = bpy.context.evaluated_depsgraph_get()
 
print("="*40)
 
def store_vertex(mesh, uvLayer, loopTriangle, loopIndex):
    loop = mesh.loops[loopIndex]
    dx = loop.vertex_index
    vert = mesh.vertices[dx]
    if loopTriangle.use_smooth:
        norm = vert.normal
    else:
        norm = loopTriangle.normal
    uv = uvLayer[loopIndex].uv
    pos = o.matrix_world @ vert.co
    pos = mat_x90 @ pos
    norm = o.matrix_world @ norm
    norm = mat_x90 @ norm       
    output_vertices.extend(pos)
    output_vertices.extend(norm)
    output_vertices.extend(uv)
 
for mesh in bpy.data.meshes:
 
    # we only export the selected object.
    if mesh.name != o.name:
        continue
 
    # get uv layer
    uv_layer = mesh.uv_layers.active and mesh.uv_layers.active.data
    if not uv_layer:
        continue
 
    # output the vertices, using simple indices.
    mesh.calc_loop_triangles()
    for lt in mesh.loop_triangles:
        va = store_vertex(mesh, uv_layer, lt, lt.loops[0])
        vb = store_vertex(mesh, uv_layer, lt, lt.loops[1])
        vc = store_vertex(mesh, uv_layer, lt, lt.loops[2])
        output_indices.append(len(output_indices))
        output_indices.append(len(output_indices))
        output_indices.append(len(output_indices))
 
# Create the header + cpp
name = o.name.lower();
 
# header
out_header_str = "" \
 +"#ifndef MODEL_" +name.upper() +"_H\n" \
 +"#define MODEL_" +name.upper() +"_H\n" \
 +"extern int nfloats_" +name +";\n" \
 +"extern int nvertices_" +name +";\n" \
 +"extern int nindices_" +name +";\n" \
 +"extern float vertices_" +name +"[];\n" \
 +"extern int indices_" +name +"[];\n" \
 +"#endif"
 
# source
out_cpp_str = "" \
 +"#include \"model_" +name +".h\"\n" \
 +"int nfloats_"      +name +" = " +str(len(output_vertices))            +";\n" \
 +"int nvertices_"    +name +" = " +str((int(len(output_vertices) / 8))) +";\n" \
 +"int nindices_"     +name +" = " +str((int(len(output_indices))))      +";\n"
 
# collect values.
out_cpp_floats = [ '%.3f' % elem for elem in output_vertices ]
out_cpp_ints   = [ '%d'   % elem for elem in output_indices ]
out_cpp_str    += "float vertices_" +name +"[] = {"  +",".join(out_cpp_floats) +"};\n"
out_cpp_str    += "int indices_"    +name +"[] = { " +",".join(out_cpp_ints)   +"};\n"
 
# write header and values.
header_filepath = bpy.path.abspath("//") +"model_" +name +".h"
cpp_filepath = bpy.path.abspath("//") +"model_" +name +".cpp"
 
f = open(cpp_filepath, 'w+')
f.write(out_cpp_str)
f.close()
 
f = open(header_filepath, "w+")
f.write(out_header_str)
f.close()
 
print("Written %s." % header_filepath)
print("Written %s." % cpp_filepath)

NAT Types This is so exciting, in this article I dive into some of the different ways a NAT device translates addresses which is important for peer-to-peer connections.
Building Cabinets In this post I dive into the design and construction of a cabinet with an interact LED strip. I also explain how I dynamically change the colors of the LEDs over TCP/UDP.
Compiling GStreamer from source on Windows How to compile GStreamer on Windows from Source using Visual Studio 2019 and the meson build system.
Debugging CMake Issues In this post I explain a process you can follow to debug issues with CMake by focusing on a specific target and making the output verbose.
Dual Boot Arch Linux and Windows 10 How to install Arch Linux and Windows 10 Pro as dual boot. A step by step tutorial how to create bootable installers, partition and setup a dual boot menu.
Mindset Updated Edition, Carol S. Dweck (Book Notes) Paragraphs I marked from the book "Mindset" from Carol S. Dweck.
How to setup a self-hosted Unifi NVR with Arch Linux A step by step HOW-TO that explain show to setup a Unifi Video Controller with an NFS share with Arch Linux.
Blender 2.8 How to use Transparent Textures Follow this node setup when you want to use an image with transparency as a "sticker".
Compiling FFmpeg with X264 on Windows 10 using MSVC A couple of steps to compile FFmpeg on Windows using MSVC.
Blender 2.8 OpenGL Buffer Exporter The following Blender script creates a [name].h and [name].cpp for the selected object and stores the positions, normals and UVs.
Blender 2.8 Baking lightmaps Light maps are a cheap way to add a lot of realism to you static scenes and have been used forever.
Blender 2.8 Tips and Tricks Use Environment Map only for reflections; create a floor plane for a Product Render, diffuse texture for roughness and more!
Setting up a Bluetooth Headset on Arch Linux Learn how to setup a Sennheiser PXC 550 Bluetooth headset on Arch Linux.
Compiling x264 on Windows with MSVC Compile the excellent x264 source on Windows using MSYS2 and MSVC.
C/C++ Snippets Is a number divisible by four?
Reading Chunks from a Buffer Some thoughts on reading bytes from a file; handy for reading NALs.
Handy Bash Commands Bash scripts: removing white space, lowercase filenames, backup using tar, etc.
Building a zero copy parser Simple solution to parse data in a pretty performant way. Used this for a RTSP protocol parser.
Kalman Filter A very simple yet powerful filter which works great when you have to smooth noisy data. Used for the Nike Rise 2.0 project.
Saving pixel data using libpng Do you have raw RGBA data that you want to save? Use this snippet to save it into a PNG file.
Compile Apache, PHP and MySQL on Mac 10.10 Setup you own PHP, MySQL and Apache and with virtual document roots.
Fast Pixel Transfers with Pixel Buffer Objects Using Pixel Buffer Objects (PBO) for fast asynchronous data transfers and OpenGL.
High Resolution Timer function in C/C++ Wait...... wait.. fast high resolution timer funtions (Windows, Linux, Mac)
Rendering text with Pango, Cairo and Freetype My never ending obsession with font rendering. A complex beast to do well. Use Pango and FreeType for the heavy lifting.
Fast OpenGL blur shader Make things look blurry ... and fast using this OpenGL blur shader.
Spherical Environment Mapping with OpenGL An old trick to get great lighting effects using Environment Maps and OpenGL.
Using OpenSSL with memory BIOs OpenSSL is a great library with lots of abstractions. In this post I discuss how to break some of these abstractions and use your own memory buffers.
Attributeless Vertex Shader with OpenGL A simple way to render a fullscreen quad without a vertex buffer with OpenGL.
Circular Image Selector Some thoughts on a different way to select images from a huge collection in a compact UI.
Decoding H264 and YUV420P playback Using libav to demux and playback with OpenGL.
Fast Fourier Transform Analyse your audio using the Fastest Fourier Transform in the West.
OpenGL Rim Shader Pretty glowy edges using a GLSL rim shader.
Rendering The Depth Buffer Render the non-linear OpenGL Depth Buffer.
Delaunay Triangulation Do you need to triangulate some shape: use the “Triangle” library.
RapidXML RapidXML is a versatile and fast XML parser with a simple API. Check out these examples.
Git Snippets Some simple GIT snippets; added here to remind myself.
Basic Shading With OpenGL A couple of basic GLSL shaders with explanation.
Open Source Libraries For Creative Coding Collection of great open source libraries for you creative programming projects.
Bouncing particle effect Snippet that can be used to create a bouncy particle effect; basic, effective, simple but nice.
OpenGL Instanced Rendering Want to render thousands and thousands of objects? Use OpenGL instanced rendering. The solution...the only solution.
Mapping a texture on a disc Ever heard about projective interpolation related to texture mapping? Learn about this intertesting issue with OpenGL and texture mapping.
Download HTML page using CURL When you want a quick solution to perform a HTTP(S) request CURL is always a quick an simple solution. Check out this example code.
Height Field Simulation on GPU Although not a Navier-Stokes implementation ... still a very nice and enjoyable effect.
OpenCV Optical Flow: when doing anything with tracking you've probably heard of it. See this simple example code using OpenCV and OpenGL.
Some notes on OpenGL FBOs and Depth Testing, using different Attachment Points, a YUV420p shader, ...
Math Meaning of the Dot Product in 3D graphics, calculating a perpendicular vector using Sam Hocevar's solution, orientation matrix and more.
Gists to remember Some gists that I want to remember, often use, etc...
Reverse SSH Do you want to login, into a remote PC but the remote PC is behind a firewall? Then use this simple reverse SSH trick which doesn't require changing your firewall rules.
Working Set Having issues with your compiler? Or during linking? Check these common issues and their solutions. I also list several tools that you can use to get a some useful info.
Consumer + Producer model with libuv Example of a common Multi Threaded Consumer/Producer Model using LibUV.
Parsing binary data Learn about the basic of a binary protocol and how to create one easily yourself.
C++ file operation snippets Reading a file into a string, vector, checking the file size, change to a position, etc. A collection of C++ file operation snippets.
Importance of blur with image gradients Do you want to experiment with OpenGL and aligning Brush Strokes along Image Gradients? Then check out this post about the importance of blurring.
Real-time oil painting with openGL Code snippet for fake "oil painting" effect with OpenGL using instanced rendering.
x264 encoder Basic example on how to use libx264 to encode image data using libav
Generative helix with openGL Screenshots of a project I worked on with that generates a DNA helix.
Mini test with vector field Screenshots while experimenting with a vector field; nothing much to see here.
Protractor gesture recognizer Testing the amazing One Dollar $1 gesture recognizer. The simplest and very good gesture recognizer.
Hair simulation Example code that implements the "Fast Simulation of Inextensible Hair and Fur" paper from M. Müller, T.Y. Kim and N.Chentanez.
Some glitch screenshots Glitch screenshots.
Working on video installation Screenshots of some experiments of a video installation.
Generative meshes I enjoy creating physics based simulations and render them on high res. Here are some experiments I did a time ago.
Converting video/audio using avconv Examples that show you how to use avconv to manipulate video and audio files.
Auto start terminal app on mac Automatically start you application whe Mac boots and make sure that it restarts your app when it exists. Handy for interactive installations.
Export blender object to simple file format Export the selected object in Blender into a .h and .cpp file that prepresents the buffer.