Fix loading shader fragments by path relative to list file

src/common/shaderloader.hpp

@@ -2,9 +2,11 @@
 #define _SHADERLOADER_H_
 
 #include <fstream>
+#include <libgen.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sstream>
+#include <unistd.h>
 
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
@@ -149,6 +151,9 @@ int loadShadersFromFile(const char* file_path, struct ShaderRegistry *registry)
    char *name;
    char *type;
    char *path;
+   char *file_path_copy = (char*) calloc(strlen(file_path), sizeof(char));
+   strncpy(file_path_copy, file_path, strlen(file_path));
+   char *base = dirname((char*) file_path_copy);
    while((size = getline(&line, &size, fp)) != -1) {
       if(size == 0) {
          // Skipping, line length 0
@@ -172,6 +177,17 @@ int loadShadersFromFile(const char* file_path, struct ShaderRegistry *registry)
          continue;
       }
 
+      // Strip trailing new lines from the path.
+      path[strcspn(path, "\n")] = 0;
+
+      // Convert any paths as relative to the basename of the file_path they
+      // were loaded from.
+      int real_path_size = strlen(base) + 1 + strlen(path) + 1;
+      char *shader_path = (char*) calloc(real_path_size, sizeof(char));
+      strncat(shader_path, base, strlen(base));
+      strcat(shader_path + strlen(base), "/");
+      strncat(shader_path + strlen(base) + 1, path, strlen(path));
+
       // Validate type
       enum ShaderType shader_type;
       if(strcmp("fragment", type) == 0) {
@@ -188,18 +204,26 @@ int loadShadersFromFile(const char* file_path, struct ShaderRegistry *registry)
          // Invalid line, unknown type.
          // @TODO Inform the user.
          free(line_copy);
+         free(shader_path);
          name = type = path = NULL;
          continue;
       }
 
-      GLuint shader_id = compile_shader(path, shader_type);
+      GLuint shader_id = compile_shader(shader_path, shader_type);
       if(shader_id == 0) {
          // Error in compilation of the shader
          // @TODO Inform the user.
          free(line_copy);
+         free(shader_path);
          name = type = path = NULL;
          continue;
       }
+
+      // Add to registry
+
+      // Cleanup
+      free(line_copy);
+      free(shader_path);
    }
    return 0;
 }