I've been trying to load my vertex shader from a file in c. Here is my code for loading the characters in a file into a string:

char* path = "shaders/vertex_shader.glsl";

if (!fopen(path, "r")) {
    printf("Could not open shader file! %s", path);
    exit(1);
}

FILE* shader = fopen(path, "r");
fseek(shader, 0, SEEK_END);
long file_size = ftell(shader);
rewind(shader);
char *vertex_shader_code = malloc(sizeof(char) * file_size   1);
fread(vertex_shader_code, sizeof(char), file_size, shader);

vertex_shader_code[file_size] = '\0';
printf("%s", vertex_shader_code);
fclose(shader);

The vertex_shader.glsl file looks like this:

#version 330 core

layout (location = 0) in vec3 positions;

void main() {
   gl_Position = vec4(positions.x, positions.y, positions.z, 1.0);
}

However, whenever I print out the vertex_shader_code string I get a bunch of garbage characters at the bottom of the file:

#version 330 core

layout (location = 0) in vec3 positions;

void main() {
   gl_Position = vec4(positions.x, positions.y, positions.z, 1.0);
}
════════

Also whenever, I try to compile the shader I get the following error:

 0(8) : error C0000: syntax error, unexpected $undefined at token "<undefined>"

Code for compiling the vertex shader:

void checkShaderCompilation(int shader_type_number, GLuint shader) {
    int success;
    char log[512];
    char* shader_type;

    switch (shader_type_number) {
        case 0: 
            shader_type = "Vertex Shader";
            break;
        case 1:
            shader_type = "Fragment Shader";
            break;
        default:
            printf("Invalid number has been provided for the shader_type_number (check function declaration)\n");
            return;
    }

    glGetShaderiv(shader, GL_COMPILE_STATUS, &success);
    
    if (!success) {
        glGetShaderInfoLog(shader, 512, NULL, log);
        printf(" %s \n Compilation ERROR:\n %s\n", shader_type, log);
        exit(1);
    }
    else {
        printf("%s compiled successfully!\n", shader_type);
    }
}

/* Compiling the vertex shader */
vertex_shader_object = glCreateShader(GL_VERTEX_SHADER); 
glShaderSource(vertex_shader_object, 1, &vertex_shader_code, NULL);
glCompileShader(vertex_shader_object);
checkShaderCompilation(0, vertex_shader_object);

CodePudding user response：

You have various off-by-one errors in your code. That part that calculates file_size and reads the shader should be (untested)...

long file_size = ftell(shader);
rewind(shader);
char *vertex_shader_code = malloc(sizeof(char) * file_size   1);
fread(vertex_shader_code, sizeof(char), file_size, shader);

vertex_shader_code[file_size] = '\0';

Notes:

1. I've removed the cast of the value returned by malloc. See here.
2. sizeof(char) is essentially redundant as it always evaluates to 1.

CodePudding user response：

It appears that I just had to open the file in binary mode:

FILE* shader  = fopen(path, "rb");