Getting garbage chars when reading GLSL files

Question

I run into the following problem.I load my shaders from files.The shader program ,when trying to compile, throws these errors for the vertex and fragment shaders:

Vertex info

0(12) : error C0000: syntax error, unexpected $undefined at token ""

Fragment info

0(10) : error C0000: syntax error, unexpected $undefined at token ""

When inspecting the loaded content of the files I can see all kinds of garbage text is attached at the beginnings and the ends of the shader files.Like this one:

#version 330 layout (location = 0) in vec4 position; layout (location = 1) in vec4 color; smooth out vec4 theColor; void main() { gl_Position = position; theColor = color; }ýýýý««««««««þîþîþîþ

The methods loading the shaders look as follows:

void ShaderLoader::loadShaders(char * vertexShaderFile,char *fragmentShaderFile){ vs = loadFile(vertexShaderFile,vlen); fs = loadFile(fragmentShaderFile,flen); } char *ShaderLoader::loadFile(char *fname,GLint &fSize){ ifstream::pos_type size; char * memblock; string text; // file read based on example in cplusplus.com tutorial ifstream file (fname, ios::in|ios::binary|ios::ate); if (file.is_open()) { size = file.tellg(); fSize = (GLuint) size; memblock = new char [size]; file.seekg (0, ios::beg); file.read (memblock, size); file.close(); cout << "file " << fname << " loaded" << endl; text.assign(memblock); } else { cout << "Unable to open file " << fname << endl; exit(1); } return memblock; }

I tried to change the encoding from UTF-8 top ANSI ,also tried to edit outside the visual studio but the problem still persists .Any help on this will be greatly appreciated.

Looks like your string isn't getting null terminated properly. — Flexo - Save the data dump
– Flexo - Save the data dump ♦, Commented Sep 8, 2011 at 7:39

datenwolf · Accepted Answer · 2011-09-08 09:56:33Z

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)); }

Ken Wayne VanderLinde · Accepted Answer · 2011-09-08 08:20:52Z

4

It looks like all you have to do is allocate one more byte of memory in which you can place a null ('\0'):

... memblock = new char[1 + fSize]; file.seekg (0, ios::beg); file.read (memblock, size); file.close(); memblock[size] = '\0'; ...

edit

I changed my code to use fSize in the array rather than size, since it is a GLint, which is just a typedef over an integer. Also, I tried this fix on my machine, and it works as far as I can tell - no junk at the beginning, and none at the end.

edited Sep 8, 2011 at 8:20

answered Sep 8, 2011 at 7:50

Ken Wayne VanderLinde

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6 Comments

Michael IV Over a year ago

I actually tried putting memblock[size] = '\0'; before the file.close(); line and it does remove the garbage from the last line.But it adds such a garbage to the beginning of the first line instead.Also I can't write "new char[size + 1]; " because size is not of int type.It gives an error.

Ken Wayne VanderLinde Over a year ago

I forgot that size is of type pos_type, not int. However, you should usually be able to cast it to an int (unless you have GLSL of several GB!). So just write new char[1 + (int)size] instead. As far as junk at the beginning of the file, I'm not sure why that would happen.

Michael IV Over a year ago

Thanks @Ken ,I cast it and the program has compiled but as I said-now I am getting the garbage in the beginning of the file .

Michael IV Over a year ago

Cool ,thanks a lot .Even that I am still having some garbage before "#version 330" line ,now the shaders compile fine !

Ken Wayne VanderLinde Over a year ago

That's very strange that you would have garbage there - maybe there's a problem with how you're inspecting the text? It would indeed be strange if the code actually compiles with garbage mixed in!

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