gray: add gpixel() and gline()

Optimized cases for gline() rely on grect() instead of reimplementing
the mechanics of the fully-optimized drawing to save some space.
pull/7/head
lephe 3 years ago
parent d7c33b12a5
commit 144ff90e37
  1. 55
      src/gray/gline.c
  2. 59
      src/gray/gpixel.c
  3. 2
      src/render/dline.c

@ -0,0 +1,55 @@
#include <gint/gray.h>
#include <gint/defs/util.h>
#include <display/common.h>
/* gline(): Bresenham line drawing algorithm
Remotely adapted from MonochromeLib code by Pierre "PerriotLL" Le Gall.
Relies on grect() for optimized situations.
@x1 @y1 @x2 @y2 Coordinates of endpoints of line (included)
@color Any color */
void gline(int x1, int y1, int x2, int y2, color_t color)
{
/* Trivial optimizations */
if(x1 == x2 || y1 == y2)
{
grect(x1, y1, x2, y2, color);
return;
}
/* Brensenham line drawing algorithm */
int i, x = x1, y = y1, cumul;
int dx = x2 - x1, dy = y2 - y1;
int sx = sgn(dx), sy = sgn(dy);
dx = abs(dx), dy = abs(dy);
gpixel(x1, y1, color);
if(dx >= dy)
{
/* Start with a non-zero cumul to even the overdue between the
two ends of the line (for more regularity) */
cumul = dx >> 1;
for(i = 1; i < dx; i++)
{
x += sx;
cumul += dy;
if(cumul > dx) cumul -= dx, y += sy;
gpixel(x, y, color);
}
}
else
{
cumul = dy >> 1;
for(i = 1; i < dy; i++)
{
y += sy;
cumul += dx;
if(cumul > dy) cumul -= dy, x += sx;
gpixel(x, y, color);
}
}
gpixel(x2, y2, color);
}

@ -0,0 +1,59 @@
#include <gint/gray.h>
#include <gint/defs/types.h>
/* gpixel(): Change a pixel's color */
void gpixel(int x, int y, color_t color)
{
if((uint)x >= 128 || (uint)y >= 64) return;
uint32_t *light, *dark;
gvram(&light, &dark);
int offset = (y << 2) + (x >> 5);
uint32_t mask = 1 << (~x & 31), tmp;
switch(color)
{
case C_WHITE:
light[offset] &= ~mask;
dark [offset] &= ~mask;
break;
case C_LIGHT:
light[offset] |= mask;
dark [offset] &= ~mask;
break;
case C_DARK:
light[offset] &= ~mask;
dark [offset] |= mask;
break;
case C_BLACK:
light[offset] |= mask;
dark [offset] |= mask;
break;
case C_NONE:
break;
case C_INVERT:
light[offset] ^= mask;
dark [offset] ^= mask;
break;
case C_LIGHTEN:
tmp = dark[offset];
dark[offset] &= light[offset] | ~mask;
light[offset] = (light[offset] ^ mask) & (tmp | ~mask);
break;
case C_DARKEN:
tmp = dark[offset];
dark[offset] |= light[offset] & mask;
light[offset] = (light[offset] ^ mask) | (tmp & mask);
break;
}
}

@ -6,7 +6,7 @@
Remotely adapted from MonochromeLib code by Pierre "PerriotLL" Le Gall.
Relies on platform-dependent dhline() and dvline() for optimized situations.
@x1 @y1 @x2 @y2 Coordinates of endpoints of line (included)
@color Any R5G6B5 color */
@color Any color accepted by dpixel() on the platform */
void dline(int x1, int y1, int x2, int y2, color_t color)
{
/* Possible optimizations */

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