diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/konsofren.h | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/src/konsofren.h b/src/konsofren.h index a209a88..525c590 100644 --- a/src/konsofren.h +++ b/src/konsofren.h @@ -100,6 +100,54 @@ static inline uint32_t kon_blendColor(uint32_t dst, uint32_t src) { return ((uint32_t)dst_a << 24) | ((uint32_t)out_r << 16) | ((uint32_t)out_g << 8) | (uint32_t)out_b; } +/* Cohen-Sutherland: clips the line to the framebuffer, returns 0 if nothing is visible */ +static int kon_outCode_(double x, double y, int width, int height) { + int code = 0; + if (x < 0) code |= 1; else if (x > width - 1) code |= 2; + if (y < 0) code |= 4; else if (y > height - 1) code |= 8; + return code; +} + +static int kon_clipLine_(int width, int height, int *x0, int *y0, int *x1, int *y1) { + double ax = *x0, ay = *y0, bx = *x1, by = *y1; + double maxX = width - 1, maxY = height - 1; + int ca = kon_outCode_(ax, ay, width, height); + int cb = kon_outCode_(bx, by, width, height); + + while (ca | cb) { + if (ca & cb) return 0; + + int out = ca ? ca : cb; + double x, y; + + if (out & 8) { + x = ax + (bx - ax) * (maxY - ay) / (by - ay); + y = maxY; + } else if (out & 4) { + x = ax + (bx - ax) * (0 - ay) / (by - ay); + y = 0; + } else if (out & 2) { + y = ay + (by - ay) * (maxX - ax) / (bx - ax); + x = maxX; + } else { + y = ay + (by - ay) * (0 - ax) / (bx - ax); + x = 0; + } + + if (out == ca) { + ax = x; ay = y; + ca = kon_outCode_(ax, ay, width, height); + } else { + bx = x; by = y; + cb = kon_outCode_(bx, by, width, height); + } + } + + *x0 = (int)(ax + 0.5); *y0 = (int)(ay + 0.5); + *x1 = (int)(bx + 0.5); *y1 = (int)(by + 0.5); + return 1; +} + /*** framebuffer implementation ***/ kon_framebuffer_t *kon_createFramebuffer(int width, int height) { @@ -239,6 +287,8 @@ void kon_fillRectangle(kon_framebuffer_t *fb, int x, int y, int width, int heigh void kon_drawLine(kon_framebuffer_t *fb, int x0, int y0, int x1, int y1, uint32_t color) { if (!fb) return; + if (!kon_clipLine_(fb->width, fb->height, &x0, &y0, &x1, &y1)) return; + int dx = abs(x1 - x0); int dy = abs(y1 - y0); |