Drawing things in C

[Mason]

Hi everybody,

This isn't an issue or something like that, but I was playing around with BareMetal OS and realized that there isn't really a library to use to draw things with.

So, I made one :)

I'm still working on some things like drawing polygons, but I've made it into a sort of usable library.

If you're interested, feel free to check it out :)

https://github.com/ohnx/libDraw

[42Bastian]

Hi Mason

Shouldn't be thickness of a line be 90 degrees to the line instead of
simple more X?


--
42Bastian

[Ian Seyler]

I tried it and it worked as intended! Good work! It would be good to implement double buffering though:

Draw scene to buffer

Copy buffer to video memory

Repeat

I might give that a try with the 3D stars demo I made.

-Ian

[Ian Seyler]

There is a small error in the put_pixel function (which was originally an error in the 3dstars app).

https://github.com/ReturnInfinity/BareMetal-OS/commit/6e444a6643d35d8f42fb2d08072ac0d089cd9663

On Tuesday, March 17, 2015 at 10:45:36 AM UTC-4, Mason wrote:

[Pablo Hugo Reda]

Hi Mason

this is antialised line and polygon draw rutine

https://github.com/phreda4/reda4/blob/master/MV/r4wine/graf.cpp

[42Bastian]

Mason

> If you're interested, feel free to check it out :)
> https://github.com/ohnx/libDraw

I wonder, why do you use floating point math. For the primitives exist
Bresenham algos which are surely faster.

(Again it is bad that the GFX chips vendors do not provide open documents.)

--
42Bastian

[Mason]

Err, I'm not very good with some aspects of math, so I pretty much just googled for and algorithm to compute a circle, line and filled circle, and just adapted them for BareMetal OS.

If you have any links to better algorithms, please send them to me and I'll have a look at them.

[Mason]

What is the size of the VideoMemory?

Is there a way to find this?

[Mason]

Pablo, thanks for the code, I'll look into it (It looks very scary, I don't know C++ :p)

Ian, I'll correct the put_pixel function in libDraw as well. As for the buffering, I'll start working on it.

42Bastian, you are absolutely correct... I was very lazy when writing the code, so I just made it increase the X. I'll probably work on it some other day when I feel like tackling that issue again :)

On Tuesday, March 17, 2015 at 10:45:36 AM UTC-4, Mason wrote:

[Simon Heath]

I have to ask, as someone who's done a lot of custom drawing code
recently and knows how hard it is to make it well... how hard would it
be to just port Cairo?

Simon

On 03/17/2015 02:40 PM, Mason wrote:
> Err, I'm not very good with some aspects of math, so I pretty much
> just googled for and algorithm to compute a circle, line and filled
> circle, and just adapted them for BareMetal OS.
> If you have any links to better algorithms, please send them to me and
> I'll have a look at them.
>
> On Tuesday, March 17, 2015 at 2:23:22 PM UTC-4, 42Bastian wrote:
>
> Mason
>
> > If you're interested, feel free to check it out :)

> > https://github.com/ohnx/libDraw <https://github.com/ohnx/libDraw>

>
> I wonder, why do you use floating point math. For the primitives
> exist
> Bresenham algos which are surely faster.
>
> (Again it is bad that the GFX chips vendors do not provide open
> documents.)
>
> --
> 42Bastian
>

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[Ian Seyler]

The size of VideoMemory can be calculated like this:

VideoX * VideoY * (VideoBPP / 4)

The clear_screen() function in 3dstars does a similar calculation.

-Ian

[Pablo Hugo Reda]

Mason

is not C++ is C!!

I spend many years optimice this algos, all integer operation.

[Mason]

Okay, great!

Another question:

How do I allocate memory?

b_mem_allocate appears to take a pointer to a long and a long number, then return another long.

What are these values?

[Mason]

Ha! I finally figured out why malloc and things like that weren't working, I was missing a library...

Added it and now I just use malloc, ignore this question...

[Mason X]

I'm not sure...
Actually, it might not be difficult. The requirements would be that BareMetal OS gets all of its "glue" for C functions done, which might not be that easy...

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