gradient question

[rayman]

hi @all,

i am looking for an easy way to draw a round gradient in the middle of my screen

does someone already have an idea or solution ?

[jamesbowman]

Well, you can use a bitmap with a gradient image like this, p.153 of the book:



I have some notes on doing it using a 1D bitmap and two passes. Will write the method up on excamera.com.

[rayman]

i am looking for something without images

[jamesbowman]

You can do it with 20 transparent circles. Might look OK!

The 1D bitmap method uses 256 bytes of main memory.

[rayman]

ok, i'm test it

have you an 1d bitmap example ?

[jamesbowman]

OK, circular gradients coded and looking quite nice:

circular(0, 0, GD.w, GD.h, 0x772b55, 0xef8619);
GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "Hello world");
GD.swap();



at:

excamera.com/sphinx/article-circular.html

[rayman]

very very nice ... thx for your fast work

[jc07]

I went through the Circular gradients document you set up. When I went to try to upload it the compiler said that circular was not declared in scope. I tried a few different versions of the gameduino library but it still didn't work. What do I need to do to use that circular gradient feature? I have posted my code for reference.
#include <SPI.h>

#include <GD23_T4.h>

void setup()

{

Serial.begin(9600); // JCB

GD.begin(0);

}



void loop()

{

GD.Clear();

circular(0, 0, GD.w, GD.h, 0x772b55, 0xef8619);

GD.cmd_text(GD.w / 2, GD.h / 2, 31, OPT_CENTER, "Hello world");

GD.swap();

}

[jamesbowman]

This is the complete example. I just fixed the code link.

github.com/jamesbowman/gd2-lib/blob/master/contrib/circular.ino