Tukukkk

I have been trying to texture a cube I have created and I am not able to see the textures. I can just see a blank cube rendering. I have tried not using a texture and making it a single color but that hasn’t worked either. I have looked at the code to see if there is anything wrong with it however I don't see any problems but I think it is because I am new to OpenGL so maybe someone else can see what is wrong with the code.

This is my texture code within vertex_array constructor:

vertex_array::vertex_array(float* vertex_buffer, int num_of_floats, const std::string& texture_file)

{

    glGenVertexArrays(1, &va_ID);

    glBindVertexArray(va_ID);



    glGenBuffers(1, &vb_ID);

    glBindBuffer(GL_ARRAY_BUFFER, vb_ID);

    glBufferData(GL_ARRAY_BUFFER, num_of_floats * sizeof(float), vertex_buffer, GL_STATIC_DRAW);

    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(0 * sizeof(float)));

    glEnableVertexAttribArray(0);

    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(float), (void*)(3 * sizeof(float)));

    glEnableVertexAttribArray(1);



    glGenTextures(1, &texture);

    glBindTexture(GL_TEXTURE_2D, texture);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

    int width, height, nrChanells;

    stbi_set_flip_vertically_on_load(true);

    unsigned char* data = stbi_load(texture_file.c_str(), &width, &height, &nrChanells, 0);

    if (data)

    {

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

        glGenerateMipmap(GL_TEXTURE_2D);

    }

    else {std::cout << "failed to load texture" << std::endl;}

    stbi_image_free(data);



    glGenBuffers(1, &ib_ID);

    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, ib_ID);

    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(index_buffer), index_buffer, GL_STATIC_DRAW);

    glBindVertexArray(0);

}

This is my shader:

#version 330 core



layout(location = 0) in vec4 position;

layout(location = 1) in vec2 texCoord;



out vec2 v_TexCoord;



uniform mat4 view;

uniform mat4 projection;



void main()

{

v_TexCoord = texCoord;

gl_Position = projection * view * position;

};



#version 330 core



layout(location = 0) out vec4 color;



in vec2 v_TexCoord;



uniform sampler2D u_Texture;



void main()

{

vec4 texColor = texture(u_Texture, v_TexCoord);

color = texColor;

//color = vec4(0.0, 0.7, 0.4, 1.0);

};

This is the shader class:

#include "shader.h"

#include <fstream>

#include <string>

#include <sstream>



shader::shader(const std::string& shader_file)

{

    std::ifstream file(shader_file);

    std::string line;

    std::stringstream shaders[2];

    std::string shader_type;



    while (getline(file, line))

    {

        if (line.find("#shader") != std::string::npos)

        {

            if (line.find("vertex") != std::string::npos)

                shader_type = "vertex";

            else if (line.find("fragment") != std::string::npos)

                shader_type = "fragment";

        }



        else

        {

            if (shader_type == "vertex")

            {

                shaders[0] << line << "n";

                //std::cout << line << "n";

            }

            else if (shader_type == "fragment")

            {

                shaders[1] << line << "n";

                //std::cout << line << "n";

            }

        }

    }



    s_ID = glCreateProgram();

    unsigned int vs_ID = glCreateShader(GL_VERTEX_SHADER);

    unsigned int fs_ID = glCreateShader(GL_FRAGMENT_SHADER);

    const char* vertex_shader = shaders[0].str().c_str();

    const char* fragment_shader = shaders[1].str().c_str(); 

    glShaderSource(vs_ID, 1, &vertex_shader, nullptr);

    glShaderSource(fs_ID, 1, &fragment_shader, nullptr);

    glCompileShader(vs_ID);

    glCompileShader(fs_ID);

    glAttachShader(s_ID, vs_ID);

    glAttachShader(s_ID, fs_ID);

    glLinkProgram(s_ID);

    glValidateProgram(s_ID);

    glDeleteShader(vs_ID);

    glDeleteShader(fs_ID);

}



void shader::bind()

{

    glUseProgram(s_ID);

}



void shader::unbind()

{

    glUseProgram(0);

}

and is my main application code:

vertex_array va_1(cube1, 40, "resources/blocks.png");

shader shader_1("src/shader1.shader");

va_1.bind();

shader_1.bind();

[Edit by Spektre]

after peaking into GLSL shader logs the problem is:

ERROR: 0:1: '' : syntax error: illegal extended ASCII character (0xdd)

which means wrong encoding somwhere along the way

No colors can mean problem with lighting/normal or just not compiled/linked shaders resulting in usage of fixed function which uses the input locations differently hence no color/texture etc.

First of all check GLSL logs as it is absolutely necessary. Even a small bug like missing ; or wrong character might prevent you from compiling and without checking you just do not know what works or not. Take a look here:

• 
  

  complete GL+GLSL+VAO/VBO C++ example

  
  
  

  And look how glGetShaderInfoLog and glGetProgramInfoLog are used. Save or print their results to check for errors.

  
  

After you done this it Looks like you got problem with encoding of the shaders:

ERROR: 0:1: '' : syntax error: illegal extended ASCII character (0xdd)

There are more reasons what could cause this:

1. 
   

   error in shader file

   
   
   

   If you edit your shader with UNICODE tools or using national keyboard or copy paste from WEB the resulting file might contain "special" characters or even the whole file could be encoded as UNICODE (UTF8,UTF16). That is wrong as gfx driver GLSL compiler can not handle such.

   
   
   

   So check the files in hex view (or write a small script that check for presence of non ASCII codes above 127).

   
   
   

   the UTF encoding is easy to detect here is a hex view of UTF8 SVG file start:

   
   
   

   EF BB BF 3C 3F 78 6D 6C 20 76 65 72 73 69 6F 6E | <?xml version
   
   

   
   
   

   Here another SVG but UTF16 this time:

   
   
   

   FF FE 3C 00 3F 00 78 00 6D 00 6C 00 20 00 76 00 | ˙ţ< ? x m l   v 
   
   

   
   
   

   As you can see the starting 2 BYTEs are the UTF magic number detecting the UTF encoding. In UTF8 character can be 1 or more bytes. In UTF16 each character has 2 bytes. This is easily detectable. But if your file has just non ASCII character (code>127) it can be very hard to spot and writing a script that detects it would be more reliable.

   
   
   

   However the error message suggest your problems are in first line so you do not need to search whole file to spot it... If you use Total Commander hit [F3] on your shader file and then hit [3] to see hex view or use any other hex view tool at your disposal.

   
   


2. 
   

   error in loading the file into your program

   
   
   

   I do not know which compiler/IDE/platform you got but If your compiler is UNICODE friendly its possible you are loading your shader file into some string variable that is enforcing UNICODE. In such case you will not found any bug in the #1 but compiler still throws illegal character.

   
   
   

   To confirm this after you load your shader into your string save it back to some file and check if its encoding is OK (do #1 on it).

   
   
   

   If the case simply stop using the string variable that do this and use array of 8 bit data types instead. Beware if you want to use char you must be sure it is char and not UNICODE Wide char instead !!! Do not ask me how search the documentation to your compiler/IDE instead.

   
   
   

   Once this is resolved (saved file is standard ASCII text) the GLSL compilation should proceed without errors...

   
   


3. 
   

   enforcing ASCII and shader code inside cpp code

   
   
   

   Some programs do not use shader files. Instead they store the source code as const strings in the app source code. This way is susceptible to the same problems as #2. To resolve this some compilers introduce a macro that tells the compiler that string is a ASCII and not UNICODE and should handle it as such. I do not know how the macros are named but I saw use them here on SE/SO in different GLSL related questions. IIRC it was something like:

   
   
   

   const char *txt=TEXT('bla bla vla');
   
   

   
   
   

   but I am not sure if it was really just TEXT or Text or something slightly different. So search the QAs for your error code or enforcing ASCII or look into your compiler/IDE documentation for such things.

   
   

Also common rookie problem is that they build entire application and only than start to compile. THAT IS WRONG. Because after that they spend eternity debugging...

They should build apps incrementally. So start small and when working move to next step. This way if a bug reveals itself its 99% time in the just added new code hence no need to difficult searching ...

The new GL api however prevents from this approach as you need to have valid GL context, VBO/VAO, mesh loader/generator, view, shaders, compatible gfx driver before the stuff even start showing something. That is a huge amount of possible problems at once. That is why I advice to start with old api and then removing part by part with the new one ... Or use some working start template instead.