/prog/ - Programming★

>>3298 (OP)

I don't know what it means that those symbols are there, and have no idea how linking actually works. But at least the archive isn't empty.

I have checked the declarations of the undefined symbols in the header against the definitions of them in the .c, and the signatures match exactly. I am able to compile and link the test program that the library comes with.

gcc lib/open-simplex-noise-in-c/open-simplex-noise-test.c -rdynamic lib/open-simplex-noise-in-c/bin/libopen-simplex-noise.a -lpng

libpng is only required by the test program, not the library itself.

So I suspect it's the link order of the original command:

... -rdynamic -lGLU -lGL -lSM -lICE -lX11 -lXext -lGLU -lGLEW -lglfw lib/open-simplex-noise-in-c/bin/libopen-simplex-noise.a -lGL -lSM -lICE -lX11 -lXext -lGLEW -lglfw

I have tried moving it to the start:

... -rdynamic lib/open-simplex-noise-in-c/bin/libopen-simplex-noise.a -lGLU -lGL -lSM -lICE -lX11 -lXext -lGLU -lGLEW -lglfw -lGL -lSM -lICE -lX11 -lXext -lGLEW -lglfw

and to the end:

... -rdynamic -lGLU -lGL -lSM -lICE -lX11 -lXext -lGLU -lGLEW -lglfw -lGL -lSM -lICE -lX11 -lXext -lGLEW -lglfw lib/open-simplex-noise-in-c/bin/libopen-simplex-noise.a

and receive the exact same errors as initially. I then tried putting it in literally every other possible position after -rdynamic, none of those succeeded either.

open-simplex-noise.c compiles with just:

gcc -c open-simplex-noise.c -Wall -Wpedantic

And the only warnings are about C99 long long constants:

open-simplex-noise.c: In function ‘open_simplex_noise’:
open-simplex-noise.c:194:16: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                ^
open-simplex-noise.c:194:40: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                                        ^
open-simplex-noise.c:195:16: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                ^
open-simplex-noise.c:195:40: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                                        ^
open-simplex-noise.c:196:16: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                ^
open-simplex-noise.c:196:40: warning: use of C99 long long integer constant [-Wlong-long]
  seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                                        ^
open-simplex-noise.c:198:17: warning: use of C99 long long integer constant [-Wlong-long]
   seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                 ^
open-simplex-noise.c:198:41: warning: use of C99 long long integer constant [-Wlong-long]
   seed = seed * 6364136223846793005LL + 1442695040888963407LL;
                                         ^

Clearly, since the test program works, the problem is with my code and not the library, it's header, or the .a. What could I have done to cause this?

To recap: .a and .h are just fine, linker is finding the .a, moving the library name around in the link command doesn't help, the declaration and definition signatures match.

>>3299

Here is the C++ code that calls into libopen-simplex-noise.a:

#include "generator.h"
#include <vector>
#include <random>
#include <iostream>
#include "open-simplex-noise.h"
using namespace glm;
using namespace std;

void getOpenSimplex (int width, int height, GLfloat feature_size, bool singleOctave, GLfloat** data) {
    int x, y;
    double value;
    double v0, v1, v2; // values from different octaves.
    struct osn_context *ctx;

    open_simplex_noise(77374, &ctx);

    for (y = 0; y < height; y++) {
        for (x = 0; x < width; x++) {
            //Get the value for (x,y)
            if (singleOctave) {
                value = open_simplex_noise4(ctx, (double) x / feature_size, (double) y / feature_size, 0.0, 0.0);
            } else {
                // Use three octaves: frequency N, N/2 and N/4 with relative amplitudes 4:2:1.
                v0 = open_simplex_noise4(ctx, (double) x / feature_size / 4,
                            (double) y / feature_size / 4, 0.0, 0.0);
                v1 = open_simplex_noise4(ctx, (double) x / feature_size / 2,
                            (double) y / feature_size / 2, 0.0, 0.0);
                v2 = open_simplex_noise4(ctx, (double) x / feature_size / 1,
                            (double) y / feature_size / 1, 0.0, 0.0);
                value = v0 * 4 / 7.0 + v1 * 2 / 7.0 + v2 * 1 / 7.0;
            }
            
            //rgb = 0x010101 * (uint32_t) ((value + 1) * 127.5);
            //data[x][y] = (0x0ff << 24) | (rgb);
            data[x][y] = value;
        }
    }
    
    open_simplex_noise_free(ctx);
}
/*
rest of the file commented out, still gives the same errors so likely not relevant.
*/

Here is the header, "open-simplex-noise.h":

#ifndef OPEN_SIMPLEX_NOISE_H__
#define OPEN_SIMPLEX_NOISE_H__

/*
 * OpenSimplex (Simplectic) Noise in C.
 * Ported to C from Kurt Spencer's java implementation by Stephen M. Cameron
 *
 * v1.1 (October 6, 2014) 
 * - Ported to C
 * 
 * v1.1 (October 5, 2014)
 * - Added 2D and 4D implementations.
 * - Proper gradient sets for all dimensions, from a
 *   dimensionally-generalizable scheme with an actual
 *   rhyme and reason behind it.
 * - Removed default permutation array in favor of
 *   default seed.
 * - Changed seed-based constructor to be independent
 *   of any particular randomization library, so results
 *   will be the same when ported to other languages.
 */

#if ((__GNUC_STDC_INLINE__) || (__STDC_VERSION__ >= 199901L))
	#include <stdint.h>
	#define INLINE inline
#elif (defined (_MSC_VER) || defined (__GNUC_GNU_INLINE__))
	#include <stdint.h>
	#define INLINE __inline
#else 
	/* ANSI C doesn't have inline or stdint.h. */
	#define INLINE
#endif

struct osn_context;

int open_simplex_noise(int64_t seed, struct osn_context **ctx);
void open_simplex_noise_free(struct osn_context *ctx);
int open_simplex_noise_init_perm(struct osn_context *ctx, int16_t p[], int nelements);
double open_simplex_noise2(struct osn_context *ctx, double x, double y);
double open_simplex_noise3(struct osn_context *ctx, double x, double y, double z);
double open_simplex_noise4(struct osn_context *ctx, double x, double y, double z, double w);

#endif

Use extern "C".

C++ uses symbol mangling, so when you compile and archive libopen-symplex-noise.a with your C compiler, the symbols are different than when you include the header with your C++ compiler.

You have 2 easy options.

Either replace

#include "open-simplex-noise.h"

With

extern "C"
{
#include "open-simplex-noise.h"
}

Or do the better and more idiomatic method of putting the following into your C header (and all your future C headers):

#ifndef OPEN_SIMPLEX_NOISE_H__
#define OPEN_SIMPLEX_NOISE_H__

#ifdef __cplusplus
extern "C" {
#endif

// Blah blah blah

#ifdef __cplusplus
}
#endif

You probably should also not be afraid of #pragma once. Every noteworthy compiler supports it.

Please read http://sscce.org/ before asking for help again. It would have been much easier to help if you had worked this down to a simple foo C function first without your preprocessor directives.

This is an example of your problem when trimmed down to its simplest form:

foo.h:

#pragma once

void foo();

foo.c:

#include "foo.h"
#include <stdio.h>
void foo()
{
    puts("Foo!");
}

test.cxx:

           
#include "foo.h"

int main()
{
    foo();
}

Compilation attempt:

$ gcc -c -ofoo.o foo.c                         
$ g++ -c -otest.o test.cxx
$ g++ -o test test.o foo.o
test.o: In function `main':
test.cxx:(.text+0x5): undefined reference to `foo()'
collect2: error: ld returned 1 exit status
$ 

And when fixed:

foo.h:

#pragma once
#ifdef __cplusplus
extern "C" {
#endif

void foo();

#ifdef __cplusplus
}
#endif

Compilation and running:

$ gcc -c -ofoo.o foo.c    
$ g++ -c -otest.o test.cxx
$ g++ -o test test.o foo.o
$ ./test
Foo!
$ 

>>3310

No worries; it wasn't inconvenient, just necessary reading when you're trying to get programming help online. It also helps for your own debugging as well.

Happy hacking!