Cannot Compile Vertex Shader: Unexpected $end at token “<EOF>”

Question

I'm having some issues with compiling my vertex shaders under OpenGL. I have a pretty standard vertex shader:

#version 330

layout(location=0) in vec4 in_Position;
layout(location=1) in vec4 in_Color;
out vec4 ex_Color;
void main(void)
{
gl_Position = in_Position;
ex_Color = in_Color;
}

and my shader loading function looks like:

string temp = LoadFile(vShaderPath);
const char* vShaderString = temp.c_str();
const char* vShaderPathC = vShaderPath.c_str();
fprintf(stderr, "File: %s \nContents: %s\n", vShaderPathC, vShaderString);
temp = LoadFile(fShaderPath);
const char* fShaderString = temp.c_str();

vShaderHandle = glCreateShader(GL_VERTEX_SHADER);
fShaderHandle = glCreateShader(GL_FRAGMENT_SHADER);

glShaderSource(vShaderHandle, 1, &vShaderString, NULL);
glShaderSource(fShaderHandle, 1, &fShaderString, NULL);

GLint compiled;

glCompileShader(vShaderHandle);
glCompileShader(fShaderHandle);

glGetShaderiv(vShaderHandle, GL_COMPILE_STATUS, &compiled);
if(compiled == false)
{
    fprintf(stderr, "ERROR: Vertex shader not compiled properly.\n");

    GLint blen = 0;
    GLsizei slen = 0;

    glGetShaderiv(vShaderHandle, GL_INFO_LOG_LENGTH , &blen);
    if (blen > 1)
    {
        GLchar* compiler_log = new GLchar[blen];
        glGetInfoLogARB(vShaderHandle, blen, &slen, compiler_log);
        fprintf(stderr, "compiler log:\n %s", compiler_log);
        delete [] compiler_log;
    }
}

but when I run my program, I get an output of:

INFO: OpenGL Version: 3.3.0 NVIDIA 310.19
File: vShader.v.glsl
Contents: #version 330

layout(location=0) in vec4 in_Position;
layout(location=1) in vec4 in_Color;
void main(void)
{
    gl_Position = in_Position;
    ex_Color = in_Color;
}

ERROR: Vertex shader not compiled properly.
compiler log:
  (0) : error C0000: syntax error, unexpected $end at token "<EOF>"

Loadfile is defined:

string ShaderEffect::LoadFile(string path)
{
    ifstream in(path.c_str(), ios::in);

    if(in.is_open())
    {

        string contents;
        in.seekg(0, ios::end);
        contents.resize(in.tellg());
        in.seekg(0, ios::beg);
        in.read(&contents[0], contents.size());
        in.close();
        return contents;
    }
    else
        throw "Problem reading file!";
}

I know the glsl code itself is not the problem because I have hard coded the string in:

const char * testvShader = {
"#version 330\n"\
"layout(location=0) in vec4 in_Position;\n"\
"layout(location=1) in vec4 in_Color;\n"\
"out vec4 ex_Color;"
"void main()\n"\
"{\n"\
"    gl_Position = in_Position;\n"\
"    ex_Color = in_Color;\n"\
"}"};

and when I switch &vShaderString to &testvShader the program runs fine. But I don't see how the loading can be the problem, because the fragment shader loads the same way and compiles and runs perfectly fine, and I print the file to the console before compiling it and it looks fine. I'm at my wits end, I can't figure out what the issue is.

PS I'm running on Fedora, if that matters.

Answer 1

You call c_str() on temp and store the result in a variable, and then you modify temp and use the saved result of c_str() . This doesn't work because the result of c_str() becomes invalid if you modify the string.

Answer 2

This compiler error is usually caused by trailing garbage. The most simple remedy is telling OpenGL which length the source string has exactly.

Replace your glShaderSource calls with

const char* vShaderString = temp.c_str();
int vertex_shader_string_length = temp.length();

/* ... */

const char* fShaderString = temp.c_str();
int fragment_shader_string_length = temp.length();

glShaderSource(vShaderHandle, 1, &vShaderString, &vertex_shader_string_length);
glShaderSource(fShaderHandle, 1, &fShaderString, &fragment_shader_string_length);