[Soc-2012-dev] Viewport FX - Week 01

[Sergej Reich]

Hey Jason,

since you're already working in this area I've got a feature
request/suggestion.
I wonder if it would be a good idea to introduce some sort of primitive
render API for the viewport.
There are a lot of places where you just want to draw simple wireframe
shapes like cubes, spheres, circles and what have you.
Instead of all systems having their own OpenGL code we could have
functions like add_line(float start[3], float end[3], float color[3],
int xray), add_box(float pos[3], float size[3], float color[3], int
xray), ... and so on.
These functions would not draw directly but just fill a buffer (or more
likely several buffers) which would be drawn at viewport refresh.

I'm interested in this not only because it would allow us to get rid of
more GL code but because it would be very useful for debugging since you
could call those functions pretty much from anywhere.

Of course this is just an idea, I haven't spent much time with blenders
drawing code yet so it might not be so simple.

Regards, Sergej.

Am Samstag, den 26.05.2012, 03:43 -0500 schrieb Jason Wilkins:
> Created the first part of an OpenGL compatibility layer: gpuImmediate
> 
> gpuImmediate is meant to be a simple and direct replacement for
> glBegin/glEnd style programming.  The goal is to reduce the work
> required to port this style of code in cases where what is being drawn
> is so simple and small that the effort to convert it to a direct
> vertex array rendering style would be costly in developer time and
> regressions.
> 
> glBegin/glEnd is inefficient for large amounts of geometry, but it has
> been highly tuned by the graphics card vendors to be about as good as
> it can possibly be.  I am not yet able to match the performance.  The
> only place I think this will matter however is in the text editor,
> which I was forced to rewrite some parts of, because it sent each
> character to the GL one. at. a. time.  Eventually I think it would be
> better to revisit the text editor by somebody interested in making it
> better generally, for now I just wanted to make sure I did not make it
> slower (it became unusable).
> 
> Next week I hope to convert everything that uses GL immediate mode to
> use the new interface.  Also, I will be centralizing much of what
> would be considered GL utility functions in various parts of Blender
> into a central location to reduce duplication (for example there are 3
> different chunks of code that draw "unit cubes" and countless "draw a
> single line" routines.
> 
> I'm keeping a day by day development diary here:
> http://wiki.blender.org/index.php/Viewport_FX_Design_Diary
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