fork of github.com/rxi/lite that removes windows support and improves useability
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
lite/src/rencache.c

304 lines
6.9 KiB

3 years ago
#include <stdio.h>
#include "rencache.h"
/* a cache over the software renderer -- all drawing operations are stored as
** commands when issued. At the end of the frame we write the commands to a grid
** of hash values, take the cells that have changed since the previous frame,
** merge them into dirty rectangles and redraw only those regions */
#define CELLS_X 80
#define CELLS_Y 50
#define CELL_SIZE 96
#define COMMAND_BUF_SIZE (1024 * 512)
enum { FREE_FONT, SET_CLIP, DRAW_TEXT, DRAW_RECT };
typedef struct {
int type, size;
RenRect rect;
RenColor color;
RenFont *font;
int tab_width;
// this was of size 0
char text[1];
} Command;
static unsigned cells_buf1[CELLS_X * CELLS_Y];
static unsigned cells_buf2[CELLS_X * CELLS_Y];
static unsigned *cells_prev = cells_buf1;
static unsigned *cells = cells_buf2;
static RenRect rect_buf[CELLS_X * CELLS_Y / 2];
static char command_buf[COMMAND_BUF_SIZE];
static int command_buf_idx;
static RenRect screen_rect;
static bool show_debug;
static inline int min(int a, int b) { return a < b ? a : b; }
static inline int max(int a, int b) { return a > b ? a : b; }
static inline int cell_idx(int x, int y) { return x + y * CELLS_X; }
/* 32bit fnv-1a hash */
#define HASH_INITIAL 2166136261
static void hash(unsigned *h, const void *data, int size)
{
const unsigned char *p = data;
while (size--)
*h = (*h ^ *p++) * 16777619;
}
static inline bool rects_overlap(RenRect a, RenRect b)
{
return b.x + b.width >= a.x && b.x <= a.x + a.width
&& b.y + b.height >= a.y && b.y <= a.y + a.height;
}
static RenRect intersect_rects(RenRect a, RenRect b)
{
int x1 = max(a.x, b.x);
int y1 = max(a.y, b.y);
int x2 = min(a.x + a.width, b.x + b.width);
int y2 = min(a.y + a.height, b.y + b.height);
return (RenRect) { x1, y1, max(0, x2 - x1), max(0, y2 - y1) };
}
static RenRect merge_rects(RenRect a, RenRect b)
{
int x1 = min(a.x, b.x);
int y1 = min(a.y, b.y);
int x2 = max(a.x + a.width, b.x + b.width);
int y2 = max(a.y + a.height, b.y + b.height);
return (RenRect) { x1, y1, x2 - x1, y2 - y1 };
}
static Command* push_command(int type, int size)
{
Command *cmd = (Command*) (command_buf + command_buf_idx);
int n = command_buf_idx + size;
if (n > COMMAND_BUF_SIZE) {
fprintf(stderr, "Warning: (" __FILE__ "): exhausted command buffer\n");
return NULL;
}
command_buf_idx = n;
memset(cmd, 0, sizeof(Command));
cmd->type = type;
cmd->size = size;
return cmd;
}
static bool next_command(Command **prev)
{
if (*prev == NULL)
*prev = (Command*) command_buf;
else
*prev = (Command*) (((char*) *prev) + (*prev)->size);
return *prev != ((Command*) (command_buf + command_buf_idx));
}
void rencache_show_debug(bool enable)
{
show_debug = enable;
}
void rencache_free_font(RenFont *font)
{
Command *cmd = push_command(FREE_FONT, sizeof(Command));
if (cmd)
cmd->font = font;
}
void rencache_set_clip_rect(RenRect rect)
{
Command *cmd = push_command(SET_CLIP, sizeof(Command));
if (cmd)
cmd->rect = intersect_rects(rect, screen_rect);
}
void rencache_draw_rect(RenRect rect, RenColor color)
{
if (!rects_overlap(screen_rect, rect))
return;
Command *cmd = push_command(DRAW_RECT, sizeof(Command));
if (cmd) {
cmd->rect = rect;
cmd->color = color;
}
}
int rencache_draw_text(RenFont *font, const char *text, int x, int y, RenColor color)
{
RenRect rect;
rect.x = x;
rect.y = y;
rect.width = ren_get_font_width(font, text);
rect.height = ren_get_font_height(font);
if (rects_overlap(screen_rect, rect)) {
int sz = strlen(text) + 1;
Command *cmd = push_command(DRAW_TEXT, sizeof(Command) + sz);
if (cmd) {
memcpy(cmd->text, text, sz);
cmd->color = color;
cmd->font = font;
cmd->rect = rect;
cmd->tab_width = ren_get_font_tab_width(font);
}
}
return x + rect.width;
}
void rencache_invalidate(void)
{
memset(cells_prev, 0xff, sizeof(cells_buf1));
}
void rencache_begin_frame(void)
{
/* reset all cells if the screen width/height has changed */
int w, h;
ren_get_size(&w, &h);
if (screen_rect.width != w || h != screen_rect.height) {
screen_rect.width = w;
screen_rect.height = h;
rencache_invalidate();
}
}
static void update_overlapping_cells(RenRect r, unsigned h)
{
int x1 = r.x / CELL_SIZE;
int y1 = r.y / CELL_SIZE;
int x2 = (r.x + r.width) / CELL_SIZE;
int y2 = (r.y + r.height) / CELL_SIZE;
for (int y = y1; y <= y2; y++) {
for (int x = x1; x <= x2; x++) {
int idx = cell_idx(x, y);
hash(&cells[idx], &h, sizeof(h));
}
}
}
static void push_rect(RenRect r, int *count)
{
/* try to merge with existing rectangle */
for (int i = *count - 1; i >= 0; i--) {
RenRect *rp = &rect_buf[i];
if (rects_overlap(*rp, r)) {
*rp = merge_rects(*rp, r);
return;
}
}
/* couldn't merge with previous rectangle: push */
rect_buf[(*count)++] = r;
}
void rencache_end_frame(void)
{
/* update cells from commands */
Command *cmd = NULL;
RenRect cr = screen_rect;
while (next_command(&cmd)) {
if (cmd->type == SET_CLIP)
cr = cmd->rect;
RenRect r = intersect_rects(cmd->rect, cr);
if (r.width == 0 || r.height == 0)
continue;
unsigned h = HASH_INITIAL;
hash(&h, cmd, cmd->size);
update_overlapping_cells(r, h);
}
/* push rects for all cells changed from last frame, reset cells */
int rect_count = 0;
int max_x = screen_rect.width / CELL_SIZE + 1;
int max_y = screen_rect.height / CELL_SIZE + 1;
for (int y = 0; y < max_y; y++) {
for (int x = 0; x < max_x; x++) {
/* compare previous and current cell for change */
int idx = cell_idx(x, y);
if (cells[idx] != cells_prev[idx])
push_rect((RenRect) { x, y, 1, 1 }, &rect_count);
cells_prev[idx] = HASH_INITIAL;
}
}
/* expand rects from cells to pixels */
for (int i = 0; i < rect_count; i++) {
RenRect *r = &rect_buf[i];
r->x *= CELL_SIZE;
r->y *= CELL_SIZE;
r->width *= CELL_SIZE;
r->height *= CELL_SIZE;
*r = intersect_rects(*r, screen_rect);
}
/* redraw updated regions */
bool has_free_commands = false;
for (int i = 0; i < rect_count; i++) {
/* draw */
RenRect r = rect_buf[i];
ren_set_clip_rect(r);
cmd = NULL;
while (next_command(&cmd)) {
switch (cmd->type) {
case FREE_FONT:
has_free_commands = true;
break;
case SET_CLIP:
ren_set_clip_rect(intersect_rects(cmd->rect, r));
break;
case DRAW_RECT:
ren_draw_rect(cmd->rect, cmd->color);
break;
case DRAW_TEXT:
ren_set_font_tab_width(cmd->font, cmd->tab_width);
ren_draw_text(cmd->font, cmd->text, cmd->rect.x,
cmd->rect.y, cmd->color);
break;
}
}
if (show_debug) {
RenColor color = { rand(), rand(), rand(), 50 };
ren_draw_rect(r, color);
}
}
/* update dirty rects */
if (rect_count > 0)
ren_update_rects(rect_buf, rect_count);
/* free fonts */
if (has_free_commands) {
cmd = NULL;
while (next_command(&cmd)) {
if (cmd->type == FREE_FONT)
ren_free_font(cmd->font);
}
}
/* swap cell buffer and reset */
unsigned *tmp = cells;
cells = cells_prev;
cells_prev = tmp;
command_buf_idx = 0;
}