Elie: Created page with "Generates a simple world map of the continents. : Input: :File:countries.data-int16-8640x4320 : Output: :File:continents-black-on-white.png : Code dependency: Code:stb_image_write.h ==Code== // Generates a black-and-white PNG world map of the continents, using NASA GPWv4 country indicator data #define IN_FILE "data/countries.data-int16-8640x4320" #define OUT_FILE "data/continents-black-on-white.png" #define INPUT_WIDTH 8640 #define..."

2022-09-01T05:52:12Z

Created page with "Generates a simple world map of the continents. : Input: File:countries.data-int16-8640x4320 : Output: File:continents-black-on-white.png : Code dependency: Code:stb_image_write.h ==Code== <syntaxhighlight lang="c"> // Generates a black-and-white PNG world map of the continents, using NASA GPWv4 country indicator data #define IN_FILE "data/countries.data-int16-8640x4320" #define OUT_FILE "data/continents-black-on-white.png" #define INPUT_WIDTH 8640 #define..."

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Generates a simple world map of the continents.
: Input: [[:File:countries.data-int16-8640x4320]]
: Output: [[:File:continents-black-on-white.png]]
: Code dependency: [[Code:stb_image_write.h]]
==Code==
<syntaxhighlight lang="c">
// Generates a black-and-white PNG world map of the continents, using NASA GPWv4 country indicator data
#define IN_FILE "data/countries.data-int16-8640x4320"
#define OUT_FILE "data/continents-black-on-white.png"
#define INPUT_WIDTH 8640
#define INPUT_HEIGHT 4320

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "stb_image_write.h"

int main() {
unsigned char *bytes = malloc(INPUT_WIDTH*INPUT_HEIGHT);
if (!bytes) {
printf("Not enough memory\n");
return -1;
}
short row[INPUT_WIDTH];
FILE* in = fopen(IN_FILE, "r");
if (in == NULL) {
perror(IN_FILE);
return 1;
}
printf("Reading %s...\n", IN_FILE);
unsigned char *p = bytes;
while (!feof(in)) {
int nRead = fread(row, sizeof(short), INPUT_WIDTH, in);
if (nRead == 0) break;
for (int i=0; i<nRead; i++) {
if (row[i] > 0 && row[i] < 1024) *(p++) = 0;
else *(p++) = 255;
}
}
fclose(in);
printf("Writing %s...\n", OUT_FILE);
if (!stbi_write_png(OUT_FILE, INPUT_WIDTH, INPUT_HEIGHT, 1, bytes, INPUT_WIDTH)) {
perror(OUT_FILE);
return 2;
}
printf("Done.\n");
free(bytes);
return 0;
}
</syntaxhighlight>

Code:continents-black-on-white.c - Revision history