dda直線描画アルゴリズム
dda直線描画アルゴリズムは、理論が説明しにくいので、ここで直接コードを貼ります.
/* Draw Line */
void line_dda(struct state *state, int x1, int y1, int x2, int y2)
{
float dx, dy, k, x, y;
int r;
int t;
dx = x1 - x2;
dy = y1 - y2;
if (abs(dx) > abs(dy))
{
if (x1 > x2)
{
t = x1; x1 = x2; x2 = t;
t = y1; y1 = y2; y2 = t;
}
k = dy / dx;
y = y1;
for (r = x1; r <= x2; r++) {
putpixel(state->screen, r, (int)(y + 0.5), COLOR_BLACK(state->screen));
y += k;
}
}
else
{
if (y1 > y2)
{
t = x1; x1 = x2; x2 = t;
t = y1; y1 = y2; y2 = t;
}
k = dx / dy;
x = x1;
for (r = y1; r <= y2; r++) {
putpixel(state->screen, (int)(x + 0.5), r, COLOR_BLACK(state->screen));
x += k;
}
}
}