Rendering an image, using C

Question

I am currently working on a program that will generate the mandelbrot set. While I am able to code the set, I do not know how to produce an image using C. Do I have to write to a new file? Do I need a special program to draw? Are there any libraries or functions that I have to use? I have a semesters worth of experience in intro C from university. I am using MinGW and eclipse if that helps.

Thanks

Answer 1

You could use something like libpng to write to PNG, but there's gonna be a learning curve there.

http://www.libpng.org/pub/png/libpng.html

Or you could write to BMP which should be simpler. This question is relevant: Writing BMP image in pure c/c++ without other libraries (check out the second answer for code)

Or you can use SDL and then: http://www.libsdl.org/release/SDL-1.2.15/docs/html/sdlsavebmp.html

Basically, you're going to need to use some kind of library unless you output a really basic file format.

Answer 2

Long ago, I wrote this code to create a .bmp image file from a 2-D array of (R, G, B) values:

#include <stdio.h>

struct Color
{
    double r, g, b; /* red, green, blue values between 0 and 1 */
};

void writeBMP(struct Color **image, int height, int width, const char* filename)
{
    unsigned int header[14];
    int i, j;
    FILE* fp = fopen(filename, "wb");
    unsigned char pad[3] = {0, 0, 0};

    header[0] = 0x4d420000;
    header[1] = 54 + 3 * height * width;
    header[2] = 0;
    header[3] = 54;
    header[4] = 40;
    header[5] = width;
    header[6] = height;
    header[7] = 0x00180001;
    header[8] = 0;
    header[9] = 3 * width * height;
    header[10] = header[11] = header[12] = header[13] = 0;

    fwrite((char*)header + 2, 1, 54, fp);
    fflush(fp);

    for(i = 0; i < height; i++)
    {
        for(j = 0; j < width; j++)
        {
            unsigned char R = 255 * image[i][j].r;
            unsigned char G = 255 * image[i][j].g;
            unsigned char B = 255 * image[i][j].b;
            fwrite(&B, 1, 1, fp);
            fwrite(&G, 1, 1, fp);
            fwrite(&R, 1, 1, fp);
        }
        fwrite(pad, width % 4, 1, fp);
    }

    fclose(fp);
}

The size of the created file is large, so you can use some library to convert the image to some other format.