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#include <stdint.h>
#include <inttypes.h>
#include <math.h>
#include "fb.h"
#include "rototiller.h"
/* Copyright (C) 2016 Vito Caputo <vcaputo@pengaru.com> */
/* Some defines for the fixed-point stuff in render(). */
#define FIXED_TRIG_LUT_SIZE 4096 /* size of the cos/sin look-up tables */
#define FIXED_BITS 11 /* fractional bits */
#define FIXED_EXP (1 << FIXED_BITS) /* 2^FIXED_BITS */
#define FIXED_MASK (FIXED_EXP - 1) /* fractional part mask */
#define FIXED_COS(_rad) costab[(_rad) % FIXED_TRIG_LUT_SIZE]
#define FIXED_SIN(_rad) sintab[(_rad) % FIXED_TRIG_LUT_SIZE]
#define FIXED_MULT(_a, _b) (((_a) * (_b)) >> FIXED_BITS)
#define FIXED_NEW(_i) ((_i) << FIXED_BITS)
#define FIXED_TO_INT(_f) ((_f) >> FIXED_BITS)
typedef struct color_t {
int r, g, b;
} color_t;
/* linearly interpolate between two colors, alpha is fixed-point value 0-FIXED_EXP. */
static inline color_t lerp_color(color_t *a, color_t *b, int alpha)
{
color_t c = {
.r = a->r + FIXED_MULT(alpha, b->r - a->r),
.g = a->g + FIXED_MULT(alpha, b->g - a->g),
.b = a->b + FIXED_MULT(alpha, b->b - a->b),
};
return c;
}
/* Return the bilinearly interpolated color palette[texture[ty][tx]] (Anti-Aliasing) */
/* tx, ty are fixed-point for fractions, palette colors are also in fixed-point format. */
static uint32_t bilerp_color(uint8_t texture[256][256], color_t *palette, int tx, int ty)
{
uint8_t itx = FIXED_TO_INT(tx), ity = FIXED_TO_INT(ty);
color_t n_color, s_color, color;
int x_alpha, y_alpha;
uint8_t nw, ne, sw, se;
/* We need the 4 texels constituting a 2x2 square pattern to interpolate.
* A point tx,ty can only intersect one texel; one corner of the 2x2 square.
* Where relative to the corner's center the intersection occurs determines which corner has been intersected,
* and the other corner texels may then be addressed relative to that corner.
* Alpha values must also be determined for both axis, these values describe the position between
* the 2x2 texel centers the intersection occurred, aka the weight or bias.
* Once the two alpha values are known, linear interpolation between the texel colors is trivial.
*/
if ((ty & FIXED_MASK) > (FIXED_EXP >> 1)) {
y_alpha = ty & (FIXED_MASK >> 1);
if ((tx & (FIXED_MASK)) > (FIXED_EXP >> 1)) {
nw = texture[ity][itx];
ne = texture[ity][(uint8_t)(itx + 1)];
sw = texture[(uint8_t)(ity + 1)][itx];
se = texture[(uint8_t)(ity + 1)][(uint8_t)(itx + 1)];
x_alpha = tx & (FIXED_MASK >> 1);
} else {
ne = texture[ity][itx];
nw = texture[ity][(uint8_t)(itx - 1)];
se = texture[(uint8_t)(ity + 1)][itx];
sw = texture[(uint8_t)(ity + 1)][(uint8_t)(itx - 1)];
x_alpha = (FIXED_EXP >> 1) + (tx & (FIXED_MASK >> 1));
}
} else {
y_alpha = (FIXED_EXP >> 1) + (ty & (FIXED_MASK >> 1));
if ((tx & (FIXED_MASK)) > (FIXED_EXP >> 1)) {
sw = texture[ity][itx];
se = texture[ity][(uint8_t)(itx + 1)];
nw = texture[(uint8_t)(ity - 1)][itx];
ne = texture[(uint8_t)(ity - 1)][(uint8_t)(itx + 1)];
x_alpha = tx & (FIXED_MASK >> 1);
} else {
se = texture[ity][itx];
sw = texture[ity][(uint8_t)(itx - 1)];
ne = texture[(uint8_t)(ity - 1)][itx];
nw = texture[(uint8_t)(ity - 1)][(uint8_t)(itx - 1)];
x_alpha = (FIXED_EXP >> 1) + (tx & (FIXED_MASK >> 1));
}
}
n_color = lerp_color(&palette[nw], &palette[ne], x_alpha);
s_color = lerp_color(&palette[sw], &palette[se], x_alpha);
color = lerp_color(&n_color, &s_color, y_alpha);
return (FIXED_TO_INT(color.r) << 16) | (FIXED_TO_INT(color.g) << 8) | FIXED_TO_INT(color.b);
}
static void init_roto(uint8_t texture[256][256], int32_t *costab, int32_t *sintab)
{
int x, y, i;
/* Generate simple checker pattern texture, nothing clever, feel free to play! */
/* If you modify texture on every frame instead of only @ initialization you can
* produce some neat output. These values are indexed into palette[] below. */
for (y = 0; y < 128; y++) {
for (x = 0; x < 128; x++)
texture[y][x] = 1;
for (; x < 256; x++)
texture[y][x] = 0;
}
for (; y < 256; y++) {
for (x = 0; x < 128; x++)
texture[y][x] = 0;
for (; x < 256; x++)
texture[y][x] = 1;
}
/* Generate fixed-point cos & sin LUTs. */
for (i = 0; i < FIXED_TRIG_LUT_SIZE; i++) {
costab[i] = ((cos((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
sintab[i] = ((sin((double)2*M_PI*i/FIXED_TRIG_LUT_SIZE))*FIXED_EXP);
}
}
/* Draw a rotating checkered 256x256 texture into fragment. (32-bit version) */
static void roto32(fb_fragment_t *fragment)
{
static int32_t costab[FIXED_TRIG_LUT_SIZE], sintab[FIXED_TRIG_LUT_SIZE];
static uint8_t texture[256][256];
static int initialized;
static color_t palette[2];
static unsigned r, rr;
int y_cos_r, y_sin_r, x_cos_r, x_sin_r, x_cos_r_init, x_sin_r_init, cos_r, sin_r;
int x, y, stride = fragment->stride / 4, width = fragment->width, height = fragment->height;
uint32_t *buf = fragment->buf;
if (!initialized) {
initialized = 1;
init_roto(texture, costab, sintab);
}
/* This is all done using fixed-point in the hopes of being faster, and yes assumptions
* are being made WRT the overflow of tx/ty as well, only tested on x86_64. */
cos_r = FIXED_COS(r);
sin_r = FIXED_SIN(r);
/* Vary the colors, this is just a mashup of sinusoidal rgb values. */
palette[0].r = (FIXED_MULT(FIXED_COS(rr), FIXED_NEW(127)) + FIXED_NEW(128));
palette[0].g = (FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[0].b = (FIXED_MULT(FIXED_COS(rr / 3), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].r = (FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].g = (FIXED_MULT(FIXED_COS(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].b = (FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(127)) + FIXED_NEW(128));
/* The dimensions are cut in half and negated to center the rotation. */
/* The [xy]_{sin,cos}_r variables are accumulators to replace multiplication with addition. */
x_cos_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), cos_r);
x_sin_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), sin_r);
y_cos_r = FIXED_MULT(-FIXED_NEW((height / 2)), cos_r);
y_sin_r = FIXED_MULT(-FIXED_NEW((height / 2)), sin_r);
for (y = 0; y < height; y++) {
x_cos_r = x_cos_r_init;
x_sin_r = x_sin_r_init;
for (x = 0; x < width; x++, buf++) {
*buf = bilerp_color(texture, palette, x_sin_r - y_cos_r, y_sin_r + x_cos_r);
x_cos_r += cos_r;
x_sin_r += sin_r;
}
buf += stride;
y_cos_r += cos_r;
y_sin_r += sin_r;
}
// This governs the rotation and color cycle.
r += FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(16)));
rr += 2;
}
/* Draw a rotating checkered 256x256 texture into fragment. (64-bit version) */
static void roto64(fb_fragment_t *fragment)
{
static int32_t costab[FIXED_TRIG_LUT_SIZE], sintab[FIXED_TRIG_LUT_SIZE];
static uint8_t texture[256][256];
static int initialized;
static color_t palette[2];
static unsigned r, rr;
int y_cos_r, y_sin_r, x_cos_r, x_sin_r, x_cos_r_init, x_sin_r_init, cos_r, sin_r;
int x, y, stride = fragment->stride / 8, width = fragment->width, height = fragment->height;
uint64_t *buf = (uint64_t *)fragment->buf;
if (!initialized) {
initialized = 1;
init_roto(texture, costab, sintab);
}
/* This is all done using fixed-point in the hopes of being faster, and yes assumptions
* are being made WRT the overflow of tx/ty as well, only tested on x86_64. */
cos_r = FIXED_COS(r);
sin_r = FIXED_SIN(r);
/* Vary the colors, this is just a mashup of sinusoidal rgb values. */
palette[0].r = (FIXED_MULT(FIXED_COS(rr), FIXED_NEW(127)) + FIXED_NEW(128));
palette[0].g = (FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[0].b = (FIXED_MULT(FIXED_COS(rr / 3), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].r = (FIXED_MULT(FIXED_SIN(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].g = (FIXED_MULT(FIXED_COS(rr / 2), FIXED_NEW(127)) + FIXED_NEW(128));
palette[1].b = (FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(127)) + FIXED_NEW(128));
/* The dimensions are cut in half and negated to center the rotation. */
/* The [xy]_{sin,cos}_r variables are accumulators to replace multiplication with addition. */
x_cos_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), cos_r);
x_sin_r_init = FIXED_MULT(-FIXED_NEW((width / 2)), sin_r);
y_cos_r = FIXED_MULT(-FIXED_NEW((height / 2)), cos_r);
y_sin_r = FIXED_MULT(-FIXED_NEW((height / 2)), sin_r);
width /= 2; /* Since we're processing 64-bit words (2 pixels) at a time */
for (y = 0; y < height; y++) {
x_cos_r = x_cos_r_init;
x_sin_r = x_sin_r_init;
for (x = 0; x < width; x++, buf++) {
uint64_t p;
p = bilerp_color(texture, palette, x_sin_r - y_cos_r, y_sin_r + x_cos_r);
x_cos_r += cos_r;
x_sin_r += sin_r;
p |= (uint64_t)(bilerp_color(texture, palette, x_sin_r - y_cos_r, y_sin_r + x_cos_r)) << 32;
*buf = p;
x_cos_r += cos_r;
x_sin_r += sin_r;
}
buf += stride;
y_cos_r += cos_r;
y_sin_r += sin_r;
}
// This governs the rotation and color cycle.
r += FIXED_TO_INT(FIXED_MULT(FIXED_SIN(rr), FIXED_NEW(16)));
rr += 2;
}
rototiller_renderer_t roto32_renderer = {
.render = roto32,
.name = "roto32",
.description = "Anti-aliased tiled texture rotation (32-bit)",
.author = "Vito Caputo <vcaputo@pengaru.com>",
.license = "GPLv2",
};
rototiller_renderer_t roto64_renderer = {
.render = roto64,
.name = "roto64",
.description = "Anti-aliased tiled texture rotation (64-bit)",
.author = "Vito Caputo <vcaputo@pengaru.com>",
.license = "GPLv2",
};
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