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dave j

Member Since 11 Oct 2002
Offline Last Active Jul 29 2016 02:34 PM

Posts I've Made

In Topic: Does Anyone Know What El Means In The Context Of Shading Equations From The B...

29 July 2016 - 06:52 AM

It's the amount of illumination emitted by a light source and is something that you define for each light. It's explained in section 5.2.

In Topic: GNU ownership, Software - an everywhere epidemic

04 October 2015 - 01:23 PM

I don't get people's hatred of GPL. If you don't like the terms of the licence it's simple - don't use the software. Same as it is with any other software. Comparing it to BSD and other more permissive licences just smacks of whining "They let me use their software as I want without paying, why don't you?". The people making such comments never seem to complain that proprietary software doesn't allow that either.

In Topic: GNU ownership, Software - an everywhere epidemic

04 October 2015 - 08:53 AM

Simply put, closed development has produced a LOT more useful software in *MODERN* times than open source.

The proportion of developers producing closed source software is far greater than that producing open source software so it would be strange if that was not the case.

Even so, as others have mentioned, open source is all over the place even in commercial products as middleware and embedded stuff.

In Topic: My first Arduino nice

23 September 2015 - 03:58 PM

This is the part I don't get about the Pi. Hardware is hard for people who have never done it. Arduinos make hardware easier, by allowing fast hookups and ready made S/W drivers for many peripherals, and a stable power supply and OTAP.

On the other hand: Software is hard for people who have never done it, and RasPis make that easy because: .... ... ... help me out here...

Why not use a PC? It's much simpler to connect to a screen. If it's a laptop it already has a screen. Who wants to get started off with programming in C? Who wants to get to know embedded linux as a first OS? It seems like hipster programming: Let's make a device that looks like an old "Sinclair". Well... Old Sinclairs ran BASIC, not C.

Honest disclosure: As an experienced software developer, the prospect of a beginner's H/W device is much more appealing to the likes of me. I am not your natural customer for a beginner's programming platform. So maybe I'm not in a good position to judge in the first place.

Pi's are the spiritual successor to the BBC Micro, which had lots of I/O ports, not the Spectrum.

You're not the target market for a Pi. Think a 12 year old kid who wants to try programming and has been inspired by seeing some devices people have built with sensors. Her not technically aware parents won't let her plug a circuit she's made into a computer costing a several $100s[1] in case she breaks it but persuading them to let her try it with one costing a few $10s is much more likely. The fact that so many of them have been bought by middle aged men who used Beebs at school just means that the Raspberry Pi Foundation had more money to spend on it's educational initiatives. ;)

Pis where originally envisaged to have Python as their main programming language and most of the learning resources created by the Foundation is geared towards that language, with Scratch as an easier introduction for younger kids.

For a programming novice, hardware programming on a Pi is easier than on an Arduino because of the development environments available. You can even do GPIO programming in Scratch now too - which has to be the most novice friendly way available.

[1] Even if it provided access to GPIO ports - find a desktop or laptop even does that.

In Topic: Is it a good idea to scale models using vertex's w component in vertex sh...

13 September 2015 - 04:48 AM

Maybe it's very simple,but i googled without success.Will there be any problem to scale models by setting vertex's w component(the last one) in vertex shader? is it free,that is to say,whether i set w or not,divided by w is performed all the time?
Besides this way only scale uniformly, are there other drawbacks?because those i googled all scaling by setting x,y,z.

It's a bad idea. Think what you will have to do if you want multiple sizes of your model in your scene, you'll have to either:

a. Update every vertex of your model and draw from CPU memory or upload it to the GPU every time you want to use it - both of which are slow.
b. Keep several copies of your model stored in GPU memory - which isn't inherently slow but you might prefer to use the GPU memory for something else. You could just prescale the x,y,z components in this case as well.

It's far better to pass a scale factor into your shader using a separate variable.