colorscrolling

I dont think so. But you can add Arduino components with the backpack. Like LED...

The gamebuino has also led . Go to tutorial section to learn it. Go hereTutorial of led

It's just a plain Cortex-M0+ architecture, so no gaming-dedicated hardware, but enough horspower to emulate all these effects to a certain extent.

Some games have already implemented rotations, zooms, palette cycling etc.

Some car races for example  ;) You definitively have to make some simple tuto if you can Alban... It's could be useful...

I know, but my code is so ugly I would have to rewrite from scratch to have something worth presenting. It was my first gamebuino project, grew organically, and I got so fed up with the Arduino IDE that I ended up writing code as it came.

My next project, if I manage to complete it, is designed a much better way, and in much better conditions ;-) I plan to document it more seriously.

Maybe you could some very short program to illustrate the technics used (and complement the already existing tuto) Your tutos / examples could be agregated later to do a workshop on doing a race car from scratch. (And then your code could be reorganised in the tuto to have a more academic code) but it's another subject. I just bouncing on this subject as tikkel was talking about one of the technics used

Try this!

#include <Gamebuino-Meta.h>

const uint8_t GRADIENT[] = {
    16,   // frame width
    2,    // frame height
    1,    // number of frames
    0,    // ?... don't understand this value
    0,    // animation speed (0 means no animation)
    0x10, // transparent color (any value greater than 0xf is transparent)
    1,    // indexed color mode
          // colormap (2 pixels per byte)
    0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef,
    0xfe, 0xdc, 0xba, 0x98, 0x76, 0x54, 0x32, 0x10
};

// must have 16 colors
const Color REFERENCE_PALETTE[] = {
    (Color)0x47e9, (Color)0x37e6, (Color)0x1fe4, (Color)0x0fe1,
    (Color)0x07a0, (Color)0x0700, (Color)0x0661, (Color)0x05c1,
    (Color)0x0501, (Color)0x0461, (Color)0x03c1, (Color)0x0320,
    (Color)0x0280, (Color)0x01e0, (Color)0x0140, (Color)0x00a0
};

const Image IMAGE(GRADIENT);

Color palette[16];

void setup() {
    gb.begin();
}

void loop() {
    while (!gb.update());

    // rotating palette
    for (uint8_t i=0; i<16; i++) {
        palette[i] = REFERENCE_PALETTE[(gb.frameCount+i)%16];
    }

    // draw image with new palette
    gb.display.setPalette(palette);
    gb.display.drawImage(32, 32, IMAGE);
}

Only works with indexed images... If you want the same effect in full RGB565, you'll have to write the bits in the right place by yourself!

It's one of the technics for simulate quick races movements. It's can been used to make water, lava, lead, grass moving with good use of colors.

OK,

so I have to paint all the effects.
Unfortunately, it is not possible to manipulate the color palette or image memory address directly on the graphics controller registers.

I was hoping to save some CPU time.

Thank you for the tips and the example.

Indeed, there's just no graphics controller :-)

What is a graphics controller?

you can manipulate the color of the palette if you use indexed colors

A specialized chip with its own memory for graphics rendering, and sometimes facilities for effects (e.g. the famous SNES mode 7)

The screen controller actually has some hardware effects, such as color inversion. No scrolling, though.

For example. gb.setRotation() also uses screen hardware to rotate the contents

... so I can change a color of the palette afterwards and this change would be visible immediately?

Yes, you don't need to redraw the image :-)