Code for this video: https://www.youtube.com/watch?v=u_rdroWi2ho

SPI_plasma.pde

#include <util/delay.h>

#include <oled.h>
#include <tri.h>

void setup()
{
    //Serial.begin( 115200 );
    oled_init();
    _delay_ms( 100 ); // Wait for the OLED display to come up.
    oled_config();
}

static const uint8_t sinustable[ 0x100 ] = {
    0x80, 0x7d, 0x7a, 0x77, 0x74, 0x70, 0x6d, 0x6a,
    0x67, 0x64, 0x61, 0x5e, 0x5b, 0x58, 0x55, 0x52,
    0x4f, 0x4d, 0x4a, 0x47, 0x44, 0x41, 0x3f, 0x3c,
    0x39, 0x37, 0x34, 0x32, 0x2f, 0x2d, 0x2b, 0x28,
    0x26, 0x24, 0x22, 0x20, 0x1e, 0x1c, 0x1a, 0x18,
    0x16, 0x15, 0x13, 0x11, 0x10, 0x0f, 0x0d, 0x0c,
    0x0b, 0x0a, 0x08, 0x07, 0x06, 0x06, 0x05, 0x04,
    0x03, 0x03, 0x02, 0x02, 0x02, 0x01, 0x01, 0x01,
    0x01, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02, 0x03,
    0x03, 0x04, 0x05, 0x06, 0x06, 0x07, 0x08, 0x0a,
    0x0b, 0x0c, 0x0d, 0x0f, 0x10, 0x11, 0x13, 0x15,
    0x16, 0x18, 0x1a, 0x1c, 0x1e, 0x20, 0x22, 0x24,
    0x26, 0x28, 0x2b, 0x2d, 0x2f, 0x32, 0x34, 0x37,
    0x39, 0x3c, 0x3f, 0x41, 0x44, 0x47, 0x4a, 0x4d,
    0x4f, 0x52, 0x55, 0x58, 0x5b, 0x5e, 0x61, 0x64,
    0x67, 0x6a, 0x6d, 0x70, 0x74, 0x77, 0x7a, 0x7d,
    0x80, 0x83, 0x86, 0x89, 0x8c, 0x90, 0x93, 0x96,
    0x99, 0x9c, 0x9f, 0xa2, 0xa5, 0xa8, 0xab, 0xae,
    0xb1, 0xb3, 0xb6, 0xb9, 0xbc, 0xbf, 0xc1, 0xc4,
    0xc7, 0xc9, 0xcc, 0xce, 0xd1, 0xd3, 0xd5, 0xd8,
    0xda, 0xdc, 0xde, 0xe0, 0xe2, 0xe4, 0xe6, 0xe8,
    0xea, 0xeb, 0xed, 0xef, 0xf0, 0xf1, 0xf3, 0xf4,
    0xf5, 0xf6, 0xf8, 0xf9, 0xfa, 0xfa, 0xfb, 0xfc,
    0xfd, 0xfd, 0xfe, 0xfe, 0xfe, 0xff, 0xff, 0xff,
    0xff, 0xff, 0xff, 0xff, 0xfe, 0xfe, 0xfe, 0xfd,
    0xfd, 0xfc, 0xfb, 0xfa, 0xfa, 0xf9, 0xf8, 0xf6,
    0xf5, 0xf4, 0xf3, 0xf1, 0xf0, 0xef, 0xed, 0xeb,
    0xea, 0xe8, 0xe6, 0xe4, 0xe2, 0xe0, 0xde, 0xdc,
    0xda, 0xd8, 0xd5, 0xd3, 0xd1, 0xce, 0xcc, 0xc9,
    0xc7, 0xc4, 0xc1, 0xbf, 0xbc, 0xb9, 0xb6, 0xb3,
    0xb1, 0xae, 0xab, 0xa8, 0xa5, 0xa2, 0x9f, 0x9c,
    0x99, 0x96, 0x93, 0x90, 0x8c, 0x89, 0x86, 0x83
};

static uint8_t charset[ 64 ] = { 0 };

static void doplasma( uint8_t * fb )
{
    static uint8_t xbuf[ 32 ];
    static uint8_t ybuf[ 16 ];
    static uint8_t c1a,c1b;
    static uint8_t c2a,c2b;
    static uint8_t c1A,c1B;
    static uint8_t c2A,c2B;
    static uint8_t x, y, i;

    c1a = c1A;
    c1b = c1B;
    for ( y = 0; y < 16; ++y ) {
        ybuf[ y ] = ( sinustable[ c1a ] + sinustable[ c1b ] ) >> 1;
        c1a += 4;
        c1b += 9;
    }
    c1A += 3;
    c1B -= 5;
    c2a = c2A;
    c2b = c2B;
    for ( x = 0; x < 32; ++x ) {
        xbuf[ x ] = ( sinustable[ c2a ] + sinustable[ c2b ] ) >> 1;
        c2a += 3;
        c2b += 7;
    }
    c2A += 2;
    c2B -= 3;
    for ( y = 0; y < 8; ++y ) {
        for ( x = 0; x < 32; ++x ) {
            for ( i = 0; i < 4; ++i, ++fb ) {
                * fb = ( charset[ ( ( ( xbuf[ x ] + ybuf[ y * 2 ] ) >> 3 ) + i ) % 16 ] & 0x0f |
                         charset[ ( ( ( xbuf[ x ] + ybuf[ y * 2 + 1 ] ) >> 3 ) + i ) % 16 ] & 0xf0 );
            }
        }
    }
}

static void makechar (void)
{
    const unsigned char bittab[ 4 ] = {
        0x11, 0x22, 0x44, 0x88
    };
    uint8_t i, ii, b, s, c;

    for ( c = 0; c < 16; ++c ) {
        s = sinustable[ c << 4 ];
        //s = c << 4;
        for ( i = 0; i < 4; ++i ){
            b = 0;
            for ( ii = 0; ii < 4; ++ii ) {
                if ( ( rand() & 0xff ) <= s ) {
                    b |= bittab[ ii ];
                }
            }
            charset[ c * 4 + i ] = b;
        }
    }
}

void loop()
{
    makechar();
    uint8_t * fb = get_fb();

    while ( 1 ) {
        transfer_frame_buffer();
        doplasma( fb );
        _delay_ms( 10 );
    }
}