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
Poll: Watches and Display...
by
440bx
[
Today
at 07:13:51 pm]
Lazarus for Windows on aa...
by
msintle
[
Today
at 06:42:18 pm]
InstallAware Using Lazaru...
by
marcov
[
Today
at 04:46:46 pm]
Who is Indy mattias?
by
paweld
[
Today
at 04:17:53 pm]
[solved] how to get class...
by
Joanna
[
Today
at 03:53:05 pm]
I just released a commerc...
by
BrassGear
[
Today
at 03:17:28 pm]
Does anyone know why thes...
by
Laksen
[
Today
at 03:04:14 pm]
Database standards OR Am ...
by
gidesa
[
Today
at 02:37:56 pm]
How to: create DLL file f...
by
TRon
[
Today
at 02:26:53 pm]
A fairly simple sound sol...
by
paweld
[
Today
at 01:46:11 pm]
Demoscene The Champs Crac...
by
KodeZwerg
[
Today
at 01:45:18 pm]
Access violation when ope...
by
Чебурашка
[
Today
at 12:27:34 pm]
Step-into the field sette...
by
Martin_fr
[
Today
at 11:31:48 am]
Access violation when re-...
by
Chris Osborne
[
Today
at 11:31:25 am]
AI, NLP and CAI: Text Gen...
by
Dzandaa
[
Today
at 11:03:26 am]
dwindows for Android
by
PierceNg
[
Today
at 10:54:44 am]
create system unit from s...
by
Laksen
[
Today
at 10:53:57 am]
[Solved] Find child contr...
by
Joanna
[
Today
at 09:53:43 am]
FpDebug unexpected Assemb...
by
Marc
[
Today
at 08:46:38 am]
Offical launch of the 1 B...
by
Handoko
[
Today
at 07:59:07 am]
Big Numbers Math
by
iLya2IK
[
Today
at 07:13:20 am]
BUG REPORT: Unable to gen...
by
dbannon
[
Today
at 06:29:49 am]
what to do if my target M...
by
Laksen
[
Today
at 12:49:12 am]
For-in loop over constant...
by
ASerge
[
Today
at 12:36:09 am]
Converting a string/index...
by
TRon
[April 18, 2024, 11:56:37 pm]
« 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 2625 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