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Bresenham's Integer line algorithm #3

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Bresenham's Integer line algorithm #3

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AbdalrahmanHafez Aug 29, 2022
b12efe8
Bresenham integer line algorithm
AbdalrahmanHafez Aug 29, 2022
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170 changes: 111 additions & 59 deletions olive.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,17 +4,31 @@
#include <stdio.h>
#include <stdint.h>
#include <errno.h>
#include <stdlib.h>
#include <stdbool.h>

typedef int Errno;

#define return_defer(value) do { result = (value); goto defer; } while (0)
#define OLIVEC_SWAP(T, a, b) do { T t = a; a = b; b = t; } while (0)
#define return_defer(value) \
do \
{ \
result = (value); \
goto defer; \
} while (0)
#define OLIVEC_SWAP(T, a, b) \
do \
{ \
T t = a; \
a = b; \
b = t; \
} while (0)
#define OLIVEC_SIGN(T, x) ((T)((x) > 0) - (T)((x) < 0))
#define OLIVEC_ABS(T, x) (OLIVEC_SIGN(T, x)*(x))
#define OLIVEC_ABS(T, x) (OLIVEC_SIGN(T, x) * (x))

void olivec_fill(uint32_t *pixels, size_t width, size_t height, uint32_t color)
{
for (size_t i = 0; i < width*height; ++i) {
for (size_t i = 0; i < width * height; ++i)
{
pixels[i] = color;
}
}
Expand All @@ -26,25 +40,30 @@ Errno olivec_save_to_ppm_file(uint32_t *pixels, size_t width, size_t height, con

{
f = fopen(file_path, "wb");
if (f == NULL) return_defer(errno);
if (f == NULL)
return_defer(errno);

fprintf(f, "P6\n%zu %zu 255\n", width, height);
if (ferror(f)) return_defer(errno);
if (ferror(f))
return_defer(errno);

for (size_t i = 0; i < width*height; ++i) {
for (size_t i = 0; i < width * height; ++i)
{
uint32_t pixel = pixels[i];
uint8_t bytes[3] = {
(pixel>>(8*0))&0xFF,
(pixel>>(8*1))&0xFF,
(pixel>>(8*2))&0xFF,
(pixel >> (8 * 0)) & 0xFF,
(pixel >> (8 * 1)) & 0xFF,
(pixel >> (8 * 2)) & 0xFF,
};
fwrite(bytes, sizeof(bytes), 1, f);
if (ferror(f)) return_defer(errno);
if (ferror(f))
return_defer(errno);
}
}

defer:
if (f) fclose(f);
if (f)
fclose(f);
return result;
}

Expand All @@ -56,17 +75,23 @@ void olivec_fill_rect(uint32_t *pixels, size_t pixels_width, size_t pixels_heigh
int x1, int y1, int w, int h,
uint32_t color)
{
int x2 = x1 + OLIVEC_SIGN(int, w)*(OLIVEC_ABS(int, w) - 1);
if (x1 > x2) OLIVEC_SWAP(int, x1, x2);
int y2 = y1 + OLIVEC_SIGN(int, h)*(OLIVEC_ABS(int, h) - 1);
if (y1 > y2) OLIVEC_SWAP(int, y1, y2);

for (int y = y1; y <= y2; ++y) {
int x2 = x1 + OLIVEC_SIGN(int, w) * (OLIVEC_ABS(int, w) - 1);
if (x1 > x2)
OLIVEC_SWAP(int, x1, x2);
int y2 = y1 + OLIVEC_SIGN(int, h) * (OLIVEC_ABS(int, h) - 1);
if (y1 > y2)
OLIVEC_SWAP(int, y1, y2);

for (int y = y1; y <= y2; ++y)
{
// TODO: move boundary checks out of the loops in olivec_fill_rect
if (0 <= y && y < (int) pixels_height) {
for (int x = x1; x <= x2; ++x) {
if (0 <= x && x < (int) pixels_width) {
pixels[y*pixels_width + x] = color;
if (0 <= y && y < (int)pixels_height)
{
for (int x = x1; x <= x2; ++x)
{
if (0 <= x && x < (int)pixels_width)
{
pixels[y * pixels_width + x] = color;
}
}
}
Expand All @@ -81,66 +106,93 @@ void olivec_fill_circle(uint32_t *pixels, size_t pixels_width, size_t pixels_hei
int cx, int cy, int r,
uint32_t color)
{
if (r == 0) return;
if (r == 0)
return;

int x1 = cx - r;
int x2 = cx + r;
if (x1 > x2) OLIVEC_SWAP(int, x1, x2);
if (x1 > x2)
OLIVEC_SWAP(int, x1, x2);

int y1 = cy - r;
int y2 = cy + r;
if (y1 > y2) OLIVEC_SWAP(int, y1, y2);
if (y1 > y2)
OLIVEC_SWAP(int, y1, y2);

for (int y = y1; y <= y2; ++y) {
for (int y = y1; y <= y2; ++y)
{
// TODO: move boundary checks out of the loops in olivec_fill_circle
if (0 <= y && y < (int) pixels_height) {
for (int x = x1; x <= x2; ++x) {
if (0 <= x && x < (int) pixels_width) {
if (0 <= y && y < (int)pixels_height)
{
for (int x = x1; x <= x2; ++x)
{
if (0 <= x && x < (int)pixels_width)
{
int dx = x - cx;
int dy = y - cy;
if (dx*dx + dy*dy <= r*r) {
pixels[y*pixels_width + x] = color;
if (dx * dx + dy * dy <= r * r)
{
pixels[y * pixels_width + x] = color;
}
}
}
}
}
}

void olivec_draw_pixel(uint32_t *pixels, size_t pixels_width, size_t pixels_height, int x, int y, uint32_t color)
{
if (x < 0 || x >= (int)pixels_width || y < 0 || y >= (int)pixels_height)
return;

pixels[y * pixels_width + x] = color;
}

// TODO: lines with different thicness
void olivec_draw_line(uint32_t *pixels, size_t pixels_width, size_t pixels_height,
int x1, int y1, int x2, int y2,
uint32_t color)
{
// TODO: fix the olivec_draw_line stairs
bool steep = abs(y2 - y1) > abs(x2 - x1);

if (steep)
{
OLIVEC_SWAP(int, x1, y1);
OLIVEC_SWAP(int, x2, y2);
}

if (x1 > x2)
{
OLIVEC_SWAP(int, x1, x2);
OLIVEC_SWAP(int, y1, y2);
}

int deltay;
if (y1 > y2)
deltay = -1;
else
deltay = 1;

int dx = x2 - x1;
int dy = y2 - y1;

if (dx != 0) {
int c = y1 - dy*x1/dx;

if (x1 > x2) OLIVEC_SWAP(int, x1, x2);
for (int x = x1; x <= x2; ++x) {
if (0 <= x && x < (int) pixels_width) {
int sy1 = dy*x/dx + c;
int sy2 = dy*(x + 1)/dx + c;
if (sy1 > sy2) OLIVEC_SWAP(int, sy1, sy2);
for (int y = sy1; y <= sy2; ++y) {
if (0 <= y && y < (int) pixels_height) {
pixels[y*pixels_width + x] = color;
}
}
}
}
} else {
int x = x1;
if (0 <= x && x < (int) pixels_width) {
if (y1 > y2) OLIVEC_SWAP(int, y1, y2);
for (int y = y1; y <= y2; ++y) {
if (0 <= y && y < (int) pixels_height) {
pixels[y*pixels_width + x] = color;
}
}
int dy = abs(y2 - y1);
int y = y1;
int error = 0;

for (int x = x1; x < x2; x++)
{
if (x < 0 || x >= (int)pixels_width)
continue;

if (steep)
olivec_draw_pixel(pixels, pixels_width, pixels_height, y, x, color);
else
olivec_draw_pixel(pixels, pixels_width, pixels_height, x, y, color);

error += dy;
if (2 * error >= dx)
{
y = y + deltay;
error -= dx;
}
}
}
Expand Down