Wsrtjtyk

I'm having an issue with my GLFW/C++ program where I am having an issue where the shaders will compile and link properly on an NVIDIA gpu but not on an intel integrated graphics card. I have been trying to fix this for hours for a school project but it seems to be getting nowhere. The shaders will compile properly on the intel side but it fails to link the shaders.

I know the shaders themselves are fine because they work in other projects I've done, it just fails in this specific one.

Here's some code for the shader linking

void ResourceManager::LoadMaterial(const std::string name, const char *prefix){



    // Load vertex program source code

    std::string filename = std::string(prefix) + std::string(VERTEX_PROGRAM_EXTENSION);

    std::string vp = LoadTextFile(filename.c_str());



    // Load fragment program source code

    filename = std::string(prefix) + std::string(FRAGMENT_PROGRAM_EXTENSION);

    std::string fp = LoadTextFile(filename.c_str());



    // Create a shader from the vertex program source code

    GLuint vs = glCreateShader(GL_VERTEX_SHADER);

    const char *source_vp = vp.c_str();

    glShaderSource(vs, 1, &source_vp, NULL);

    glCompileShader(vs);



    // Check if shader compiled successfully

    GLint status;

    glGetShaderiv(vs, GL_COMPILE_STATUS, &status);

    if (status != GL_TRUE){

        char buffer[512];

        glGetShaderInfoLog(vs, 512, NULL, buffer);

        throw(std::ios_base::failure(std::string("Error compiling vertex shader: ")+std::string(buffer)));

    }



    // Create a shader from the fragment program source code

    GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);

    const char *source_fp = fp.c_str();

    glShaderSource(fs, 1, &source_fp, NULL);

    glCompileShader(fs);



    // Check if shader compiled successfully

    glGetShaderiv(fs, GL_COMPILE_STATUS, &status);

    if (status != GL_TRUE){

        char buffer[512];

        glGetShaderInfoLog(fs, 512, NULL, buffer);

        throw(std::ios_base::failure(std::string("Error compiling fragment shader: ")+std::string(buffer)));

    }



    // Create a shader program linking both vertex and fragment shaders

    // together

    GLuint sp = glCreateProgram();

    glAttachShader(sp, vs);

    glAttachShader(sp, fs);

    glLinkProgram(sp);



    // Check if shaders were linked successfully

    glGetProgramiv(sp, GL_LINK_STATUS, &status);

    if (status != GL_TRUE){

        char buffer[512];

        glGetShaderInfoLog(sp, 512, NULL, buffer);

        throw(std::ios_base::failure(std::string("Error linking shaders: ")+std::string(buffer)));

    }



    // Delete memory used by shaders, since they were already compiled

    // and linked

    glDeleteShader(vs);

    glDeleteShader(fs);



    // Add a resource for the shader program

    AddResource(Material, name, sp, 0);

}

If you need other parts of the code I'll be happy to provide more but this is where it seems to fail on the intel side.

I really hope there's a dead simple fix to this that I have not found because this is a hair-pulling issue. Thanks in advance.

addendum #1: error code

Error linking shaders: ╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠: iostream stream error

Addendum #2 Cmake code

    cmake_minimum_required(VERSION 2.6)



# Name of project

project(IlluminationDemo)



# Specify project files: header files and source files

set(HDRS

    asteroid.h camera.h game.h model_loader.h resource.h resource_manager.h scene_graph.h scene_node.h

)



set(SRCS

    asteroid.cpp camera.cpp game.cpp main.cpp resource.cpp resource_manager.cpp scene_graph.cpp scene_node.cpp material_fp.glsl material_vp.glsl metal_fp.glsl metal_vp.glsl plastic_fp.glsl plastic_vp.glsl textured_material_fp.glsl textured_material_vp.glsl three-term_shiny_blue_fp.glsl three-term_shiny_blue_vp.glsl three-term_textured_fp.glsl three-term_textured_vp.glsl three-term_toon_fp.glsl three-term_toon_vp.glsl

)



# Add path name to configuration file

configure_file(path_config.h.in path_config.h)



# Add executable based on the source files

add_executable(IlluminationDemo ${HDRS} ${SRCS})



# Require OpenGL library

find_package(OpenGL REQUIRED)

include_directories(${OPENGL_INCLUDE_DIR})

target_link_libraries(IlluminationDemo ${OPENGL_gl_LIBRARY})



# Other libraries needed

set(LIBRARY_PATH "" CACHE PATH "Folder with GLEW, GLFW, GLM, and SOIL libraries")

include_directories(${LIBRARY_PATH}/include)

if(NOT WIN32)

    find_library(GLEW_LIBRARY GLEW)

    find_library(GLFW_LIBRARY glfw)

    find_library(SOIL_LIBRARY SOIL)

elseif(WIN32)

    find_library(GLEW_LIBRARY glew32s HINTS ${LIBRARY_PATH}/lib)

    find_library(GLFW_LIBRARY glfw3 HINTS ${LIBRARY_PATH}/lib)

    find_library(SOIL_LIBRARY SOIL HINTS ${LIBRARY_PATH}/lib)

endif(NOT WIN32)

target_link_libraries(IlluminationDemo ${GLEW_LIBRARY})

target_link_libraries(IlluminationDemo ${GLFW_LIBRARY})

target_link_libraries(IlluminationDemo ${SOIL_LIBRARY})



# The rules here are specific to Windows Systems

if(WIN32)

    # Avoid ZERO_CHECK target in Visual Studio

    set(CMAKE_SUPPRESS_REGENERATION TRUE)



    # This will use the proper libraries in debug mode in Visual Studio

    set_target_properties(IlluminationDemo PROPERTIES DEBUG_POSTFIX _d)

endif(WIN32)

Addendum #3 Shader code

Fragment Shader

// Illumination based on the traditional three-term model



#version 130



// Attributes passed from the vertex shader

in vec3 position_interp;

in vec3 normal_interp;

in vec3 light_pos[2];

in vec3 camera_pos;



// Material attributes (constants)

vec4 ambient_color = vec4(0.0, 0.1, 0.0, 1.0);

vec4 diffuse_color = vec4(0.4, 0.8, 0.3, 1.0);

vec4 specular_color = vec4(0.9, 0.9, 0.9, 1.0);

float phong_exponent = 128.0;





void main() 

{

    // Blinn-Phong shading



    vec3 N, // Interpolated normal for fragment

         L, // Light-source direction

         V, // View direction

         H; // Half-way vector

    for(int i = 0; i < light_pos.length; i++){

    // Compute Lambertian lighting Id

    N = normalize(normal_interp);





    L = (light_pos[i] - position_interp);

    L = normalize(L);



    float Id = max(dot(N, L), 0.0);

    Id = round(Id*2.0) / 2.0;



    // Compute specular term for Blinn-Phong shading

    // V = (eye_position - position_interp);

    V = camera_pos - position_interp; // Eye position is (0, 0, 0) in view coordinates

    V = normalize(V);



    //H = 0.5*(V + L); // Halfway vector

    H = (V + L); // Halfway vector

    H = normalize(H);



    float spec_angle_cos = max(dot(N, H), 0.0);

    float Is = pow(spec_angle_cos, phong_exponent);

    Is = round(Is*2.0) / 2.0;



    if(dot(V,N) > mix(0.5, 0.5, max(0.0, dot(N,L)))){

    // Assign light to the fragment

    gl_FragColor += ambient_color + Id*diffuse_color + Is*specular_color;

    } else {



        gl_FragColor = vec4(0.0,0.0,0.0,1.0) * (ambient_color + Id*diffuse_color + Is*specular_color);

    }

    }





    // For debug, we can display the different values

    //gl_FragColor = ambient_color;

    //gl_FragColor = diffuse_color;

    //gl_FragColor = specular_color;

    //gl_FragColor = color_interp;

    //gl_FragColor = vec4(N.xyz, 1.0);

    //gl_FragColor = vec4(L.xyz, 1.0);

    //gl_FragColor = vec4(V.xyz, 1.0);

}



// Illumination based on the traditional three-term model

Vertex Shader

#version 130



// Vertex buffer

in vec3 vertex;

in vec3 normal;

in vec3 color;



// Uniform (global) buffer

uniform mat4 world_mat;

uniform mat4 view_mat;

uniform mat4 projection_mat;

uniform mat4 normal_mat;

uniform vec3 cameraPos;



// Attributes forwarded to the fragment shader

out vec3 position_interp;

out vec3 normal_interp;

out vec3 camera_pos;

out vec3 light_pos[2];



// Material attributes (constants)

//

// Could be loaded from a configuration file and also passed with the

// uniform buffer

vec3 light_position = vec3(-0.5, -0.5, 1.5);

vec3 light_position2 = vec3(4.0, -1.0, -1.0);





void main()

{

    camera_pos = cameraPos;

    // Transform vertex position

    gl_Position = projection_mat * view_mat * world_mat * vec4(vertex, 1.0);



    // Transform vertex position without including projection

    position_interp = vec3(view_mat * world_mat * vec4(vertex, 1.0));



    // Transform normal

    normal_interp = vec3(normal_mat * vec4(normal, 0.0));



    // Transform light position to align with view

    light_pos[0] = vec3(view_mat * vec4(light_position, 1.0));

    light_pos[1] = vec3(view_mat * vec4(light_position2, 1.0));

}

Addendum #4 Seem like the issue has to do with how the array light_pos is being passed between the shaders then the program freaks out when light_pos.length is called. Clarification on this would be appreciated.

Addendum #5 Graphics Adapters tested:
Intel:
HD 4600,
HD 5600,
HD 615
,,NVidia:
GTX 750 ti,
GTX 1080,
GTX 970m

As clearly specified in GLSL specification version 1.30; 5.7 Structure and Array Operations; page 46, length is a method and not a member and the correct syntax for to use is:

vec3 light_pos[2];



int l = light_pos.length();

Change light_pos.length by light_pos.length() to solve your issue.

Of course it is still surprising that the compiler doesn't generate an error message in this case.

In my case the NVIDIA driver accepted light_pos.length as if it were light_pos.length().

Of course the Intel HD driver accepted light_pos.length(). Using light_pos.length didn't give any error message, but it causes an access violation at glLinkProgram.