Introducing the OGRE fork on GitHub

in this post I want to introduce the OGRE fork on github. The goal of the fork is to provide a stable and reliable OGRE 1.x series while at the same time modernizing parts under the hood updates.

The idea behind this is that there are many existing 1.x codebases, actually a whole 1.x ecosystem, that can be modernized that way.
The last release of the 1.x series was over 2 years ago, so using the current 1.10 branch already gives a lot of improvements.

However the 1.10 branch contains some unnecessary changes that make it incompatible to the 1.9 release. These were reverted, so old code should compile again.

Additionally there are modernizing changes when compared with the upstream at bitbucket, which are discussed in more detail in the following.

This will be still a high-level overview though. If you need even more details, take a look on the git-ChangeLog.

Replace legacy renderers

With 1.9 the only stable renderers were GL(2.0) and DX9 which by today are outdated and produce different results than the GLES2 renderer that is used for Web and Mobile, which makes porting applications harder.

Therefore the goal is to get the GL3Plus renderer into a shape where it can act as a drop-in replacement for the old GL render and then drop the latter.

You can see the current status here – while it says that only 41/86 tests pass, most of the failed tests actually only differ in only 1 or 2 pixels which is pretty good when considering we are comparing fixed function vs. dynamically generated shaders (RTSS).

But the fork does not stop here; the GL renderers now also share the context creation code. This allows using the GLES2 renderer on the desktop or creating a GL3+ context using EGL – which is a prerequisite for headless rendering and for running on Wayland/MIR. Overall this makes your applications much more portable.

Improved regression testing

Changing the renderer requires being able to continuously monitor whether the rendering is still correct and to immediately detect regressions.

For this the Testing and VisualTesting frameworks were fixed and now correctly run on Linux and OSX. They run on each pull request to catch errors before the code even touches master.

Furthermore the tests can now be built without input handling (OIS) which hopefully will lead to wider adoption.

The unit tests still use cppunit which is a pain to use when compared to gtest, but changing that would require a large rewrite.

Batteries Included

The build now automatically handles the dependencies by downloading and building them as needed. On all platforms. So you do not have to care about mismatching compile settings any more.

Furthermore the SampleBrowser can now be build without input handling which eases quick testing. And in case you want input, now SDL2 is used instead of the esoteric and outdated OIS.

Next bringing your applications to the web is now easier; OGRE was able to run in the browser for a long time already – but the process was only badly documented. The fork tracks the Emscripten sample code inside the repository and also has documentation on how to use it.

Bindings for Scripting Languages

For using scripting languages, there is traditionally MOGRE (C#), Ogre4j, Python-Ogre which are by now basically all outdated and unmaintained.

To put all these efforts on a solid foundation I took some inspiration from ruby-ogre and added SWIG support.

At the time of writing there are already working Python bindings (see sample here) and a proof-of-concept for C#.

By using SWIG it is now easily to add further bindings for Ruby, Java, JavaScript (Node.js) as well. But as I care mostly for Python this will be an exercise for the reader.

A word on OGRE 2.1

You might wonder why one should care about the 1.x and not go for 2.1 directly. The obvious reason is that you have an existing codebase and OGRE 2.1 drastically changes API and even the material file format.

Then, while faster than 1.x, OGRE 2.x is still far from feature completeness with 1.x – it still completely lacks Web and Mobile support.
Faster also actually depends on your scene/ material usage; For instance, if you only render a single object (product showcase) 2.x will not offer you any advantages.

Finally the main functionality advance in 2.1, namely the new material system (HLMS) and with it physically based shading were backported to 1.x.

Yet if you only care about desktop and want to render large immersive worlds (lots of nodes, lots of materials), 2.1 is the way to go.

 

 

Learning Modern 3D Graphics Programming

one of the best resources to learn modern OpenGL and the one which helped me quite a lot is the Book at www.arcsynthesis.org/gltut/ – or lets better say was. Unfortunately the domain expired so the content is no longer reachable.

Luckily the Book was designed as an open source project and the code to generate the website is still available at Bitbucket. Unfortunately this repository does not seem to be actively maintained any more.

Therefore I set out to make the Book to be available again using Github Pages. You can find the results here:

https://paroj.github.io/gltut/

However I did not simply mirror the pages, but also improved it at several places. So what has changed so far?

Continue reading Learning Modern 3D Graphics Programming

meCoffee PID controller Review for the Rancilio Silvia

The Rancilio Silvia Espresso Machine has one major weakness: the high fluctuation of the default thermostat.
The taste of the espresso already varies with temperature deviations as small as 1°C, but the thermostat of the Silvia V3, V4 has a range of ~20°C (~30°C for Silvia V1, V2).

a thermostat having a hard time keeping the target temperature of 110°C

So to get a decent tasting espresso one need to predict the heating phase of the boiler, which is called temperature surfing. However this involves wasting water and one also needs the right timing which is especially difficult for beginners.

PID Controlled Temperature

A better solution to is to replace the default thermostat with a digital one. This means adding microcontroller that will monitor the temperature using the PID algorithm. This way you always have the right temperature – without surfing. Furthermore the microcontroller can be used to add some fancy features to the machine like preinfusion or a shot timer.

Continue reading meCoffee PID controller Review for the Rancilio Silvia

Rust prevention on Rancilio Silvia

The main point one can criticise about the build of the Rancilio Silvia is that it is not all stainless steel. While many important parts like the drip tray and the cup holder are, the main frame (black) is just powder coated steel. This means it can rust and according to reports on the internet it actually does.
However one can do some small and cheap modifications to drastically reduce the risk.

Rust is the product of the reaction of steel and oxygen in the presence of water, so to prevent rust one either has to remove oxygen or water.
The powder coating of the frame typically removes both, but over time scratches penetrate the coating and the frame can rust.

Prevent Scratches

The first step to prevent rust is therefore to prevent scratches on the steel frame. To this end one can add small rubber knobs (8mm diameter) at places where movable parts come in contact with the frame

Prevent Water Splashes

The other thing one can do is to ensure that less water come in contact with the frame. Unfortunately the drain on the Silvia is quite short, so water splashes in all directions and can run behind the drip tray – especially if it is not moved all the way back. See the following video:

An easy fix to improve the situation is to extend the drain with a silicon pipe (19mm inner diameter) for about 4cm. After the modification, the water hardly splashes any more. (again this is the worst-case scenario with the drip tray all the way in the front)

Header Image CC-sa-by Darkone

Changing the Fan on the Corsair CS550M

While the Corasair CS550M is a good power supply unit (PSU), the fan or more specifically the fan bearing is quite poor. Even though the fan is temperature controlled, this results in a annoying clickering noise. Therefore one might want to replace it with a better quality, more quite fan.

In order to do so, you will need the following tools:

  • soldering iron
  • shrink-on tube
  • diagonal cutter
  • flat nose pliers
  • convenience: cable stripper

However note that the used high power capacitors store enough charge to shock you even several minutes after disconnecting the PSU. So you should wait for about 10minutes after disconnecting the PSU and even then watch out not to touch the pins of the capacitors.

If you set-up everything correctly, follow these steps to silence your corsair:

now you can re-asseble the PSU housing and optionally attach the tacho cable to a free plug on your mainboard to monitor the PSU fan.

This post was inspired by this youtube video. The pc fan connector diagram was made by pavouk.org.

Converting a Ubuntu and Windows dual-boot installation to UEFI

UEFI is the successor to BIOS for communicating with the Firmware on your Mainboard.
While the first BIOS was released with the IBM-PC in 1981, the first UEFI version (EFI 2.0) was released 25 years later in 2006 building upon the lessons learned in that timespan. So UEFI is without any doubt the more modern solution.

The user-visible advantages of using UEFI instead of BIOS are

You could reinstall both Windows and Ubuntu to get UEFI. However it is also possible to convert existing installations of both on the fly – without the backup/ restore cycle. You should still do a backup in case something goes wrong though.

Prerequisites

Only the 64bit Versions of Windows support UEFI. Therefore this guide assumes that you run the 64bit versions of both Windows and Ubuntu.

Furthermore verify the following items before you continue – otherwise you will not be able to finish the conversion. Use GParted in case you have not enough space before the first or after the last partition.

  • 250MB space in front of first partition
    Typically Windows 8 creates a 350MB System Partition upon installation. This space can be reclaimed for a 100MB EFI partiton and a new 100MB Windows System partition.
  • 1-2MB behind last partiton (for the GPT backup)
  • UEFI bootable Ubuntu USB drive.
    You can use the startup disk creator on ubuntu with an Ubuntu 14.04+ ISO.
  • UEFI bootable Windows USB drive.
    You can use the Microsoft Media Creation tool for Windows 10 to get one.

to test that the sticks are indeed UEFI compatible, try booting them with CSM Mode disabled in your BIOS.

Convert the drive to GPT

UEFI requires a GUID Partition Table (GPT), so first we need to convert from MBR to GPT.

After this step you will not be able to boot your system any more. So make sure you have the Ubuntu USB drive ready.

We will use gdisk to perform the conversion as following:

sudo gdisk /dev/sdX
Command (? for help): w

where sdX is your system drive (e.g. sda)

Convert Windows to UEFI

Now boot your Windows USB drive and enter the command prompt as described in this Microsoft Technet article at step 6.

Continue with the following steps from the Article. Note that we have skipped steps 1-4 as we used Ubuntu to convert the disk to GPT.

We have now created a EFI partition, a new EFI compatible Windows System Partition and we have installed the Windows Bootloader to the EFI partition. Your Windows installation should now start again.
At this point you could also perform an upgrade to Windows 10, as the upgrade would erase grub from the EFI partition anyway.

Next we are going to install grub to the EFI partition and make it manage the boot.

Enter a Ubuntu chroot

As we can not directly boot our Ubuntu installation, we will instead boot from the Ubuntu USB drive and the switch to the installed Ubuntu.
To do the switch we have to setup and enter a chroot as following

sudo mount /dev/sdXY /mnt 
sudo mount /dev/sdX1 /mnt/boot/efi 
sudo mount -o bind /dev /mnt/dev
sudo mount -o bind /sys /mnt/sys
sudo mount -t proc /proc /mnt/proc
sudo cp /proc/mounts /mnt/etc/mtab
sudo cp /etc/resolv.conf /mnt/etc/resolv.conf
sudo chroot /mnt

where sdXY is the partition where your Ubuntu system is installed (e.g. sda5)

Convert Ubuntu to UEFI

Inside your Ubuntu Installation we have to replace grub for BIOS (aka grub-pc) with grub for UEFI (aka grub-efi) as:

sudo apt-get --reinstall install grub-common grub-efi-amd64 os-prober

this would be enough to get the system booting again, however we also aim for secure boot so we also need to install the following:

sudo apt-get install shim-signed grub-efi-amd64-signed linux-signed-generic

This installs signatures for grub and the kernel which are used to verify the integrity of these at boot. Furthermore we install shim, which is a passthrough bootloader that translates from the Microsoft signatures on you mainboard to the signatures by Canonical used to sign grub and the kernel (see this for details).

Next we finally install grub to the EFI partition by:

sudo grub-install --uefi-secure-boot /dev/sdX
sudo update-grub

where sdX is again your system drive (e.g. sda).

Now you can enable secure boot in your BIOS and benefit. Note that some BIOS implementations additionaly require you to select the trusted signatures. Look out for an option called “Install Default Secure Boot keys” or similar to select the Microsoft signatures.

State of the xpad Xbox Controller Driver

Since my last post regarding the Xbox 360 Wireless Controller on Ubuntu, I have spent quite some time digging through different version of the xpad driver and their issues.

The following issues are those I encountered with xpad upstream at the time I wrote the first post. Some of them are fixed by now,  while for others the fixes are pending – but lets start from the beginning..

However if all you want is a driver where the mentioned bugs are fixed

Head over here

Continue reading State of the xpad Xbox Controller Driver

Silencing the IcyBox IB-RD3620SU3

The IcyBox is a good  RAID case with USB3.0 support – however the stock fan is quite loud as it causes some vibrations.

In this tutorial we will replace it with a Noiseblocker PR-1 BlackSilentPro Fan which is not only silent but also has a better cooling performance.

In order to perform the depicted steps you will need the following tools

  • soldering iron
  • shrink-on tube
  • diagonal cutter

 

Note however that as the height of the Noiseblocker is 25mm instead of the 10mm of the stock fan it will stand out from the case.

Updating Crucial MX100 Firmware with Ubuntu

There has been a Firmware update for the Crucial MX100 to MU02. In case you are running Ubuntu there is an easy way to perform the update without using a CD or USB Stick.

As the firmware comes in form of an iso image containing Tiny Core Linux, we can instruct grub2 to directly boot from it. Here is how:

  1. append the following to /etc/grub.d/40_custom:
    menuentry "MX100 FW Update" {
     set isofile="/home/<USERNAME>/Downloads/MX100_MU02_BOOTABLE_ALL_CAP.iso"
     # assuming your home is on /dev/sda3 ATTENTION: change this so it matches your setup
     loopback loop (hd0,msdos3)$isofile
     linux (loop)/boot/vmlinuz libata.allow_tpm=1 quiet base loglevel=3 waitusb=10 superuser rssd-fw-update rssd-fwdir=/opt/firmware rssd-model=MX100
     initrd (loop)/boot/core.gz
    }

    read this for details of the file format.

  2. run sudo update-grub
  3. reboot and select “MX100 FW Update”
  4. Now you can delete the menuentry created in step1

Note that this actually much “cleaner” than using windows where you have to download 150MB of the Crucial Store Executive Software which actually is a local webserver written in Java (urgh!). But all it can do is display some SMART monitoring information and automatically perform the above steps on windows.

Header Image CC-by MiNe

OpenGL Matrices – the missing bits

While generally the available documentation on how the OpenGL matrices work is quite good, there are some missing bits. Although not necessary for your everyday rendering, they give one some insight on how rasterization in general and OpenGL in special works.

W coordinate after perspective divide

After conversion to normalized device coordinates(ndc) one might think each vertex looks like

$$ \vec{v}_{ndc} = \frac{1}{w} \begin{pmatrix} x \\ y \\ z \\ w \end{pmatrix} = \begin{pmatrix} \frac{x}{w} \\ \frac{y}{w} \\ \frac{z}{w} \\ 1 \end{pmatrix} $$

however it looks more like

$$ \vec{v}_{ndc} = \begin{pmatrix} \frac{x}{w} \\ \frac{y}{w} \\ \frac{z}{w} \\ \frac{1}{w} \end{pmatrix} $$

the $w$ coordinate is not divided by itself, but is inverted instead. This is done because the interpolation between vertices still needs to take place and for perspective correct interpolation one needs the camera space depth $z = -w_{cam}$.

$$\begin{eqnarray}
\vec{v}_{\alpha} &=& \frac{(1-\alpha)\frac{\vec{v}_0}{-z_0}  + \alpha\frac{\vec{v}_1}{-z_1}}
{(1-\alpha)\frac{1}{-z_0} + \alpha \frac{1}{-z_1}} \\
&=& \frac{(1-\alpha)\vec{v}_0 w_{0_{ndc}} + \alpha\vec{v}_1 w_{1_{ndc}}}
{(1-\alpha) w_{0_{ndc}} + \alpha w_{1_{ndc}}}
\end{eqnarray} $$

instead of dividing by $-z$ we can multiply with $w_{ndc}$ as multiplication is faster than division.

Note that for brevity the given formula assumes a scanline based rasterizer as it interpolates only between two vertices. The general approach is to use barycentric coordinates to interpolate between all three vertices simultaneously.

Row major or column major

Even though even Wikipedia says OpenGL is column major, it is actually storage agnostic. However by default it interprets your 16 element array as:

$$ \begin{bmatrix}
m_0 & m_4& m_8 & m_{12}\\
m_1 & m_5& m_9  & m_{13}\\
m_2 & m_6& m_{10}  & m_{14}\\
m_3 & m_7& m_{11}  & m_{15}
\end{bmatrix}$$

Yet most OpenGL functions dealing with matrices offer a transpose parameter which you can use to specify the used order. For a comparison of storage orders see the Eigen documentation.