Hi, This is really cool. I have been working on a similiar fast SPI libarary that uses double buffering, but for the TLC5940 as I don't really like the library thats out there...
When I look at your matrix, I think I gotta see Plasma on it. 
I took a look at your library and the example code and saw you avoid using floats so you might appreciate this attached program .. I adapted my fast plasma generator program I use to test my library in development to work with your library. Im curious to see the performance of your display if you or someone with a similar setup can test it. I guarantee you will think this is some pretty wicked eye candy should you try it. It has a gamma correction table, which I think I saw you were requesting somewhere.. Its very fast as it uses only integer math and some other tricks for trigonometric calculations.
//PlazINT - Fast Plasma Generator using Integer Math Only
//Edmund "Skorn" Horn
//March 4,2013
//Version 1.0 adapted for OctoWS2811Lib (untested)
//#include <Arduino.h> // Not sure if this is needed.
#include <avr/pgmspace.h>
#include <OctoWS2811.h>
//OctoWS2811 Defn. Stuff
#define COLS_LEDs 40 //all of the following params need to be adjusted for screen size
#define LEDS_PER_STRIP 120 //40x3(r,g,b)
#define ROWS_LEDs 8
#define NUM_LEDs 960 //40 cols x 8 rows x 3 leds(rgb)
const int ledsPerStrip = 120;
DMAMEM int displayMemory[LEDS_PER_STRIP*6];
int drawingMemory[LEDS_PER_STRIP*6];
const int config = WS2811_GRB | WS2811_800kHz;
OctoWS2811 leds(ledsPerStrip, displayMemory, drawingMemory, config);
//Byte val 2PI Cosine Wave, offset by 1 PI
//supports fast trig calcs and smooth LED fading/pulsing.
uint8_t const cos_wave[256] PROGMEM =
{0,0,0,0,1,1,1,2,2,3,4,5,6,6,8,9,10,11,12,14,15,17,18,20,22,23,25,27,29,31,33,35,38,40,42,
45,47,49,52,54,57,60,62,65,68,71,73,76,79,82,85,88,91,94,97,100,103,106,109,113,116,119,
122,125,128,131,135,138,141,144,147,150,153,156,159,162,165,168,171,174,177,180,183,186,
189,191,194,197,199,202,204,207,209,212,214,216,218,221,223,225,227,229,231,232,234,236,
238,239,241,242,243,245,246,247,248,249,250,251,252,252,253,253,254,254,255,255,255,255,
255,255,255,255,254,254,253,253,252,252,251,250,249,248,247,246,245,243,242,241,239,238,
236,234,232,231,229,227,225,223,221,218,216,214,212,209,207,204,202,199,197,194,191,189,
186,183,180,177,174,171,168,165,162,159,156,153,150,147,144,141,138,135,131,128,125,122,
119,116,113,109,106,103,100,97,94,91,88,85,82,79,76,73,71,68,65,62,60,57,54,52,49,47,45,
42,40,38,35,33,31,29,27,25,23,22,20,18,17,15,14,12,11,10,9,8,6,6,5,4,3,2,2,1,1,1,0,0,0,0
};
//Gamma Correction Curve
uint8_t const exp_gamma[256] PROGMEM=
{0,0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,3,3,3,3,3,
4,4,4,4,4,5,5,5,5,5,6,6,6,7,7,7,7,8,8,8,9,9,9,10,10,10,11,11,12,12,12,13,13,14,14,14,15,15,
16,16,17,17,18,18,19,19,20,20,21,21,22,23,23,24,24,25,26,26,27,28,28,29,30,30,31,32,32,33,
34,35,35,36,37,38,39,39,40,41,42,43,44,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,
61,62,63,64,65,66,67,68,70,71,72,73,74,75,77,78,79,80,82,83,84,85,87,89,91,92,93,95,96,98,
99,100,101,102,105,106,108,109,111,112,114,115,117,118,120,121,123,125,126,128,130,131,133,
135,136,138,140,142,143,145,147,149,151,152,154,156,158,160,162,164,165,167,169,171,173,175,
177,179,181,183,185,187,190,192,194,196,198,200,202,204,207,209,211,213,216,218,220,222,225,
227,229,232,234,236,239,241,244,246,249,251,253,254,255
};
void setup()
{
leds.begin();
leds.show();
}
void loop()
{
long frameCount=25500; // arbitrary seed to calculate the three time displacement variables t,t2,t3
while(1)
{
uint16_t pixelIndex=0;
frameCount++ ;
uint16_t t = fastCosineCalc((42 * frameCount)/100); //time displacement - fiddle with these til it looks good...
uint16_t t2 = fastCosineCalc((35 * frameCount)/100);
uint16_t t3 = fastCosineCalc((38 * frameCount)/100);
for (uint8_t y = 0; y < ROW_LEDs; y++)
{
for (uint8_t x = 0; x < COLS_LEDs ; x++)
{
uint8_t r = fastCosineCalc(((x << 3) + (t >> 1) + fastCosineCalc((t2 + (y << 3))))); //Calculate 3 seperate plasma waves, one for each color channel
uint8_t g = fastCosineCalc(((y << 3) + t + fastCosineCalc(((t3 >> 2) + (x << 3)))));
uint8_t b = fastCosineCalc(((y << 3) + t2 + fastCosineCalc((t + x + (g >> 2)))));
//uncomment the following to enable gamma correction
//r=pgm_read_byte_near(exp_gamma+r);
//g=pgm_read_byte_near(exp_gamma+g);
//b=pgm_read_byte_near(exp_gamma+b);
leds.setPixel(pixelIndex, (r << 16) | (g << 8) | b)); // Is this the fastest method to update the draw buffer with colors?
pixelIndex++;
}
}
leds.show(); // not sure if this function is needed to update each frame
}
}
inline uint8_t fastCosineCalc( uint16_t preWrapVal)
{
uint8_t wrapVal = (preWrapVal % 255);
if (wrapVal<0) wrapVal=255+wrapVal;
return (pgm_read_byte_near(cos_wave+wrapVal));
}
Thanks.