c++ - OpenGL shaders don't compile

Question

The shaders in my OpenGL project don't compile. I have Ubuntu 16.04 LTS, using CLion. Didn't find any solution, that's why asking here.

Here is my errorlist:

ATTENTION: default value of option force_s3tc_enable overridden by environment.
ERROR::SHADER::VERTEX::COMPILATION_FAILED
0:1(1): error: syntax error, unexpected $end

ERROR::SHADER::FRAGMENT::COMPILATION_FAILED
0:1(1): error: syntax error, unexpected $end

ERROR::SHADER::PROGRAM::LINKING_FAILED
error: linking with uncompiled shadererror: linking with uncompiled shader

Here's my main.cpp code:

#include <iostream>

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

// GLFW
#include <GLFW/glfw3.h>

// Other includes
#include "Shader.h"

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// The MAIN function, from here we start the application and run the game loop
int main( )
{
    // Init GLFW
    glfwInit( );

    // Set all the required options for GLFW
    glfwWindowHint( GLFW_CONTEXT_VERSION_MAJOR, 3 );
    glfwWindowHint( GLFW_CONTEXT_VERSION_MINOR, 3 );
    glfwWindowHint( GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE );
    glfwWindowHint( GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE );

    glfwWindowHint( GLFW_RESIZABLE, GL_FALSE );

    // Create a GLFWwindow object that we can use for GLFW's functions
    GLFWwindow *window = glfwCreateWindow( WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr );

    int screenWidth, screenHeight;
    glfwGetFramebufferSize( window, &screenWidth, &screenHeight );

    if ( nullptr == window )
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate( );

        return EXIT_FAILURE;
    }

    glfwMakeContextCurrent( window );

    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers
    if ( GLEW_OK != glewInit( ) )
    {
        std::cout << "Failed to initialize GLEW" << std::endl;
        return EXIT_FAILURE;
    }

    // Define the viewport dimensions
    glViewport( 0, 0, screenWidth, screenHeight );

    // Build and compile our shader program
    Shader ourShader( "core.vs", "core.frag" );


    // Set up vertex data (and buffer(s)) and attribute pointers
    GLfloat vertices[] =
            {
                    // Positions         // Colors
                    0.5f, -0.5f, 0.0f,   1.0f, 0.0f, 0.0f,  // Bottom Right
                    -0.5f, -0.5f, 0.0f,   0.0f, 1.0f, 0.0f,  // Bottom Left
                    0.0f,  0.5f, 0.0f,   0.0f, 0.0f, 1.0f   // Top
            };
    GLuint VBO, VAO;
    glGenVertexArrays( 1, &VAO );
    glGenBuffers( 1, &VBO );
    // Bind the Vertex Array Object first, then bind and set vertex buffer(s) and attribute pointer(s).
    glBindVertexArray( VAO );

    glBindBuffer( GL_ARRAY_BUFFER, VBO );
    glBufferData( GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW );

    // Position attribute
    glVertexAttribPointer( 0, 3, GL_FLOAT, GL_FALSE, 6 * sizeof( GLfloat ), ( GLvoid * ) 0 );
    glEnableVertexAttribArray( 0 );
    // Color attribute
    glVertexAttribPointer( 1, 3, GL_FLOAT, GL_FALSE, 6 * sizeof( GLfloat ), ( GLvoid * )( 3 * sizeof( GLfloat ) ) );
    glEnableVertexAttribArray( 1 );

    glBindVertexArray( 0 ); // Unbind VAO

    // Game loop
    while ( !glfwWindowShouldClose( window ) )
    {
        // Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
        glfwPollEvents( );

        // Render
        // Clear the colorbuffer
        glClearColor( 0.2f, 0.3f, 0.3f, 1.0f );
        glClear( GL_COLOR_BUFFER_BIT );

        // Draw the triangle
        ourShader.Use( );
        glBindVertexArray( VAO );
        glDrawArrays( GL_TRIANGLES, 0, 3 );
        glBindVertexArray(0);

        // Swap the screen buffers
        glfwSwapBuffers( window );
    }

    // Properly de-allocate all resources once they've outlived their purpose
    glDeleteVertexArrays( 1, &VAO );
    glDeleteBuffers( 1, &VBO );

    // Terminate GLFW, clearing any resources allocated by GLFW.
    glfwTerminate( );

    return EXIT_SUCCESS;
}

Shader.h code:

#ifndef SHADER_H
#define SHADER_H

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

#include <GL/glew.h>
#include <cstring>

class Shader
{
public:
    GLuint Program;
    // Constructor generates the shader on the fly
    Shader( const GLchar *vertexPath, const GLchar *fragmentPath )
    {
        // 1. Retrieve the vertex/fragment source code from filePath
        std::string vertexCode;
        std::string fragmentCode;
        std::ifstream vShaderFile;
        std::ifstream fShaderFile;
        // ensures ifstream objects can throw exceptions:
        vShaderFile.exceptions ( std::ifstream::badbit );
        fShaderFile.exceptions ( std::ifstream::badbit );
        try
        {
            // Open files
            vShaderFile.open( vertexPath );
            fShaderFile.open( fragmentPath );
            std::stringstream vShaderStream, fShaderStream;
            // Read file's buffer contents into streams
            vShaderStream << vShaderFile.rdbuf( );
            fShaderStream << fShaderFile.rdbuf( );
            // close file handlers
            vShaderFile.close( );
            fShaderFile.close( );
            // Convert stream into string
            vertexCode = vShaderStream.str( );
            fragmentCode = fShaderStream.str( );
        }
        catch ( std::ifstream::failure e )
        {
            std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
        }
        const GLchar *vShaderCode = vertexCode.c_str( );
        const GLchar *fShaderCode = fragmentCode.c_str( );
        // 2. Compile shaders
        GLuint vertex, fragment;
        GLint success;
        GLchar infoLog[512];
        // Vertex Shader
        vertex = glCreateShader( GL_VERTEX_SHADER );
        glShaderSource( vertex, 1, &vShaderCode, NULL);
        glCompileShader( vertex );
        // Print compile errors if any
        glGetShaderiv( vertex, GL_COMPILE_STATUS, &success );
        if ( !success )
        {
            glGetShaderInfoLog( vertex, 512, NULL, infoLog );
            std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED
" << infoLog << std::endl;
        }
        // Fragment Shader
        fragment = glCreateShader( GL_FRAGMENT_SHADER );
        glShaderSource( fragment, 1, &fShaderCode, NULL);
        glCompileShader( fragment );
        // Print compile errors if any
        glGetShaderiv( fragment, GL_COMPILE_STATUS, &success );
        if ( !success )
        {
            glGetShaderInfoLog( fragment, 512, NULL, infoLog );
            std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED
" << infoLog << std::endl;
        }
        // Shader Program
        this->Program = glCreateProgram( );
        glAttachShader( this->Program, vertex );
        glAttachShader( this->Program, fragment );
        glLinkProgram( this->Program );
        // Print linking errors if any
        glGetProgramiv( this->Program, GL_LINK_STATUS, &success );
        if (!success)
        {
            glGetProgramInfoLog( this->Program, 512, NULL, infoLog );
            std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED
" << infoLog << std::endl;
        }
        // Delete the shaders as they're linked into our program now and no longer necessery
        glDeleteShader( vertex );
        glDeleteShader( fragment );

    }
    // Uses the current shader
    void Use( )
    {
        glUseProgram( this->Program );
    }
};

#endif

Here's my core.vs:

#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 color;
layout (location = 2) in vec2 texCoord;

out vec3 ourColor;
out vec2 TexCoord;

void main()
{
    gl_Position = vec4(position, 1.0f);
    ourColor = color;
    // We swap the y-axis by substracing our coordinates from 1. This is done because most images have the top y-axis inversed with OpenGL's top y-axis.
    // TexCoord = texCoord;
    TexCoord = vec2(texCoord.x, 1.0 - texCoord.y);
}

...and core.frag:

#version 330 core
in vec3 ourColor;
in vec2 TexCoord;

out vec4 color;

// Texture samplers
uniform sampler2D ourTexture1;

void main()
{
// Linearly interpolate between both textures (second texture is only slightly combined)
color = texture(ourTexture1, TexCoord);
}

I've also attached my CMakeLists.txt. Hope it helps:

cmake_minimum_required(VERSION 3.9)
project(STUDY_GL)

set(CMAKE_CXX_STANDARD 11)

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++14 -pthread -fpermissive")

find_package (OpenGL REQUIRED)
find_package (GLUT REQUIRED)
find_package (glfw3 REQUIRED)
find_library (glew REQUIRED)
find_library (glad REQUIRED)


include_directories(${/usr/include/GLFW/})
include_directories(${/usr/include/GL/})


file(GLOB SOURCE_FILES
        *.cpp
        *.h
        )

add_executable(main.cpp ${SOURCE_FILES} Shader.h)

target_link_libraries (main.cpp ${OPENGL_LIBRARIES} ${GLUT_LIBRARIES} ${GLFW3_LIBRARIES} -lGL -lglfw -lglut -lGLEW)

I have an SOIL2 directory inside a project. Here's its link.

Answer 1

In general you code is fine, but you have to pass std::ifstream::failbit to std::ios::exceptions, because if std::ifstream::open fails, the failbit state flag is set.

vShaderFile.exceptions ( std::ifstream::failbit | std::ifstream::badbit );
fShaderFile.exceptions ( std::ifstream::failbit | std::ifstream::badbit );
try
{
   vShaderFile.open( vertexPath );
   fShaderFile.open( fragmentPath );
   .....
}
catch ( std::ifstream::failure e )
{
    std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
}

I bet that your working directory is not proper set. Use an absolute file path to the shader files for debug reasons.
If the shader source files cannot be accessed, and your code does not throw any exception, then you try to compile empty strings. This causes the error messages.

By the way, since you do not use any texture in the code snippet posted in your question, you should do the following changes to your fragment shader:

// color = texture(ourTexture1, TexCoord); <--- skip
color = vec4(ourColor,1.0);                <--- add