OpenGL shader loading fails

Question

I'm having a problem with my shader loading code. The bizarre thing that's confusing me is that it works maybe once in 5 times, but then only sort of works. For instance, it'll load the frag shader, but then texturing won't work properly (it'll draw a strange semblance of the texture over the geometry instead). I think the problem is with the loading code, so that's what my question is about. Can anyone spot an error I haven't found in the code below?

char* vs, * fs;

vertexShaderHandle   = glCreateShader(GL_VERTEX_SHADER);
fragmentShaderHandle = glCreateShader(GL_FRAGMENT_SHADER);

long sizeOfVShaderFile = getSizeOfFile(VERTEX_SHADER_FILE_NAME);
long sizeOfFShaderFile = getSizeOfFile(FRAGMENT_SHADER_FILE_NAME);

if(sizeOfVShaderFile == -1)
{
    cerr << VERTEX_SHADER_FILE_NAME<<" is null!  Exiting..." << endl;
    return;
}
if(sizeOfFShaderFile == -1)
{
    cerr << FRAGMENT_SHADER_FILE_NAME<<" is null!  Exiting..." << endl;
    return;
}

vs = readFile(VERTEX_SHADER_FILE_NAME);
fs = readFile(FRAGMENT_SHADER_FILE_NAME);

const char* vv = vs, *ff = fs;

glShaderSource(vertexShaderHandle  , 1, &vv, NULL);

cout << "DEBUGGING SHADERS" << endl;
cout << "VERTEX SHADER:  ";
printShaderInfoLog(vertexShaderHandle);
cout << endl;

glShaderSource(fragmentShaderHandle, 1, &ff, NULL);

cout << "FRAGMENT SHADER:  ";
printShaderInfoLog(fragmentShaderHandle);
cout << endl;


glCompileShader(vertexShaderHandle);

cout << "VERTEX SHADER:  ";
printShaderInfoLog(vertexShaderHandle);
cout << endl;

glCompileShader(fragmentShaderHandle);

cout << "FRAGMENT SHADER:  ";
printShaderInfoLog(fragmentShaderHandle);
cout << endl;


programHandle = glCreateProgram();

cout << "DEBUGGING PROGRAM" << endl;

glAttachShader(programHandle, vertexShaderHandle);

printProgramInfoLog(programHandle);

glAttachShader(programHandle, fragmentShaderHandle);

printProgramInfoLog(programHandle);


glLinkProgram(programHandle);

printProgramInfoLog(programHandle);

glUseProgram(programHandle);

printProgramInfoLog(programHandle);


delete[] vs; delete[] fs;

Here's the readFile function:

char* readFile(const char* path)
{
    unsigned int fileSize = getSizeOfFile(path);

    char* file_data = new char[fileSize];

    ifstream input_stream;

    input_stream.open(path, ios::binary);

    input_stream.read(file_data, fileSize);

    input_stream.close();
    //this is deleted at the end of the shader code
    return file_data;
}

All of the below messages are from the exact same executable (no rebuild).

Here's the first possible error message:

BallGLWidget::initializeGL called
DEBUGGING SHADERS
VERTEX SHADER:  
FRAGMENT SHADER:  
VERTEX SHADER:  ERROR: 0:17: '<' : syntax error syntax error


FRAGMENT SHADER:  
DEBUGGING PROGRAM
ERROR: One or more attached shaders not successfully compiled

ERROR: One or more attached shaders not successfully compiled

glGetError enum value:  GL_NO_ERROR

Another possible error message:

BallGLWidget::initializeGL called
DEBUGGING SHADERS
VERTEX SHADER:  
FRAGMENT SHADER:  
VERTEX SHADER:  ERROR: 0:17: 'tt' : syntax error syntax error


FRAGMENT SHADER:  ERROR: 0:33: '?' : syntax error syntax error


DEBUGGING PROGRAM
ERROR: One or more attached shaders not successfully compiled

ERROR: One or more attached shaders not successfully compiled

Here's the output when it works (maybe 1 in 5 or 6 times)

BallGLWidget::initializeGL called
DEBUGGING SHADERS
VERTEX SHADER:  
FRAGMENT SHADER:  
VERTEX SHADER:  
FRAGMENT SHADER:  
DEBUGGING PROGRAM
Image format is GL_RGB
Checking textures...
glGetError enum value:  GL_NO_ERROR

I seriously doubt its the shaders themselves since they do work sometimes... and the reported errors are garbage.

If any more information would be helpful I'll gladly provide it.

EDIT: Here's the shaders

The vertex shader:

attribute vec2 a_v_position;
attribute vec2 a_tex_position;

varying   vec2 tex_coord_output;


void main()
{
    tex_coord_output = a_tex_position;

    gl_Position = vec4(a_v_position, 0.0, 1.0);
}

The fragment shader:

varying vec2 tex_coord_output;

uniform sampler2D ballsampler;


void main()
{
        gl_FragColor = texture2D(ballsampler, tex_coord_output);
}

Answer 1

Your question is a duplicate of Getting garbage chars when reading GLSL files and here's my answer to it:

---

You're using C++, so I suggest you leverage that. Instead of reading into a self allocated char array I suggest you read into a std::string:

#include <string>
#include <fstream>

std::string loadFileToString(char const * const fname)
{
    std::ifstream ifile(fname);
    std::string filetext;

    while( ifile.good() ) {
        std::string line;
        std::getline(ifile, line);
        filetext.append(line + "\n");
    }

    return filetext;
}

That automatically takes care of all memory allocation and proper delimiting -- the keyword is RAII: Resource Allocation Is Initialization. Later on you can upload the shader source with something like

void glcppShaderSource(GLuint shader, std::string const &shader_string)
{
    GLchar const *shader_source = shader_string.c_str();
    GLint const shader_length = shader_string.size();

    glShaderSource(shader, 1, &shader_source, &shader_length);
}

void load_shader(GLuint shaderobject, char * const shadersourcefilename)
{
    glcppShaderSource(shaderobject, loadFileToString(shadersourcefilename));
}

Answer 2

You are reading the files but as far as I can see you are not zero-terminating the text. Try allocating filesize+1 and set the last char to zero.