Lazarus
Home
Help
TinyPortal
Search
Login
Register
Lazarus
»
Forum
»
Programming
»
Graphics and Multimedia
»
Graphics
(Moderator:
Ask
) »
How do I read the RGBA values of a pixel from a surface or texture with SDL2?
Free Pascal
Website
Downloads
Wiki
Documentation
Bugtracker
Mailing List
Lazarus
Website
Downloads (Laz+FPC)
Packages (OPM)
FAQ
Wiki
Documentation (RTL/FCL/LCL)
Bugtracker
CCR Bugs
IRC channel
GIT
Mailing List
Other languages
Foundation
Website
Useful Wiki Links
Project Roadmap
Getting the Source
Screenshots
How to use the forum
About donations (wiki)
Bookstore
Computer Math and Games in Pascal
(preview)
Lazarus Handbook
Search
Advanced search
Recent
add new targets to make
by
Key-Real
[
Today
at 06:04:22 pm]
Unlocking Files
by
KodeZwerg
[
Today
at 06:03:08 pm]
[SOLVED] trunk bug for mi...
by
Key-Real
[
Today
at 05:56:32 pm]
Demo Scene Bitmap Font Sc...
by
Gigatron
[
Today
at 05:56:27 pm]
Compile/Convert Delphi pr...
by
Martin_fr
[
Today
at 05:43:11 pm]
Generics - correct syntax
by
Thaddy
[
Today
at 05:40:59 pm]
Parameter passing odditie...
by
Thaddy
[
Today
at 05:35:41 pm]
Lazarus for Windows on aa...
by
msintle
[
Today
at 05:32:42 pm]
InstallAware Using Lazaru...
by
msintle
[
Today
at 05:26:36 pm]
Xcode Command Line Tools ...
by
Joseph
[
Today
at 05:16:39 pm]
Offical launch of the 1 B...
by
Hartmut
[
Today
at 04:49:29 pm]
what to do if my target M...
by
nickysn
[
Today
at 04:16:02 pm]
compiler error in unit
by
paule32
[
Today
at 03:49:50 pm]
how to tweek fpmake to co...
by
Key-Real
[
Today
at 02:33:27 pm]
Can function be used for ...
by
VisualLab
[
Today
at 02:15:30 pm]
Multithreading - synchron...
by
mika
[
Today
at 01:48:51 pm]
A fairly simple sound sol...
by
KodeZwerg
[
Today
at 01:48:26 pm]
May be useful to somebody
by
KodeZwerg
[
Today
at 12:38:22 pm]
match automatic highlight...
by
Чебурашка
[
Today
at 11:35:14 am]
Tchart with dual numbers ...
by
wp
[
Today
at 10:48:18 am]
Debugger crashes with App...
by
Martin_fr
[
Today
at 09:29:46 am]
Copyrights Q
by
BrassGear
[
Today
at 09:13:14 am]
[SOLVED] how to build the...
by
Key-Real
[
Today
at 09:12:33 am]
Quirky windows
by
tetrastes
[
Today
at 08:59:06 am]
How can I draw a rectangl...
by
Handoko
[
Today
at 07:30:55 am]
« previous
next »
Print
Pages: [
1
]
Author
Topic: How do I read the RGBA values of a pixel from a surface or texture with SDL2? (Read 2629 times)
semichaud1
New Member
Posts: 38
How do I read the RGBA values of a pixel from a surface or texture with SDL2?
«
on:
December 01, 2019, 05:26:37 pm »
Hi,
How do I read the RGBA values of a specific pixel, at given coordinates x and y, from a surface or texture with SDL2 in Free Pascal?
Thanks.
Logged
piXelicidio
Newbie
Posts: 3
Re: How do I read the RGBA values of a pixel from a surface or texture with SDL2?
«
Reply #1 on:
December 17, 2019, 02:45:38 pm »
Hi, you can't or shouldn't read pixels from a texture because its on GPU memory.
Only from surfaces:
When you create the surface with (
https://wiki.libsdl.org/SDL_CreateRGBSurface
) maybe with 32 bits in the deph parameter.
Then it returns an structure (record):
https://wiki.libsdl.org/SDL_Surface
There you can get and access anytime the "pixels" pointer.
From that record you need also pitch to make your custom getpixel and setpixel.
Logged
metis
Sr. Member
Posts: 300
Re: How do I read the RGBA values of a pixel from a surface or texture with SDL2?
«
Reply #2 on:
December 20, 2019, 06:09:09 pm »
@semichaud1
and then try it with
SDL_GetDisplayDPI(...); // Get diagonal, horizontal, vertical DPI
and
SDL_GetRGBA(...); // Get the Pixel's RGBA-Values
Logged
Life could be so easy, if there weren't those f*** Details.
My FFmpeg4Lazarus =
FFPlay4Laz
+
FFGrab4Laz
+ FFInfo4Laz
metis
Sr. Member
Posts: 300
Re: How do I read the RGBA values of a pixel from a surface or texture with SDL2?
«
Reply #3 on:
May 30, 2020, 04:49:46 pm »
@semichaud1
with
'SDL_RenderReadPixels()'
you may get the Pixels from a Texture w/o creating a Surface in Your Code, see:
https://discourse.libsdl.org/t/most-efficient-way-of-getting-render-pixels/27581
.
Logged
Life could be so easy, if there weren't those f*** Details.
My FFmpeg4Lazarus =
FFPlay4Laz
+
FFGrab4Laz
+ FFInfo4Laz
Print
Pages: [
1
]
« previous
next »
Lazarus
»
Forum
»
Programming
»
Graphics and Multimedia
»
Graphics
(Moderator:
Ask
) »
How do I read the RGBA values of a pixel from a surface or texture with SDL2?
TinyPortal
© 2005-2018