CODEWITHSUNDEEP
c++openglglfw
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Reputation: 123

Why would the window created with this OpenGL context open as transparent?

Upon execution, the background should be rendered as a darker-blue, but I have clearly missed something. The window is instead rendered with a background that is identical to the image immediately behind it (e.g. other open windows or the desktop, etc.). I cannot identify the problem.

Currently I am not using any -std during compilation and I am utilizing the following linkages with the output executable:

-lGL -lGLU -lGLEW -lglfw3 -lX11 -lXxf86vm -lXrandr -lpthread -lXi -ldl -lXcursor -lXinerama

Here are the contents of my .cpp file:

#include <stdio.h>
#include <stdio.h>

#include <GL/glew.h>

#include <GLFW/glfw3.h>
GLFWwindow* window;

#include <glm/glm.hpp>
using namespace glm;

int main( void )
{

    //Initialize GLFW
    if( !glfwInit() )
    {
        fprintf( stderr, "Failes to intialize GLFW\n" );
        return -1;
    }

    glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing
    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);

    // Open a Window and create it's OpenGL context
    window = glfwCreateWindow( 1024, 768, "playground", NULL, NULL);
    if( window == NULL) {
        fprintf( stderr, "Failed to open GLFW window.\n" );
        glfwTerminate();
        return -1;
    }

    glfwMakeContextCurrent(window);
    glewExperimental = true;
    if (glewInit() != GLEW_OK) {
        fprintf(stderr, "Failed to initialize GLEW\n");
        return -1;
    }

    glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

    // Dark blue background
    glClearColor(0.0f, 0.0f, 0.4f, 0.0f);

    do{

        glfwSwapBuffers(window);
        glfwPollEvents();

    }

    while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
           glfwWindowShouldClose(window) == 0 );

    glfwTerminate();

    return 0;

}

I am an OpenGL newcomer. Feel free to remark on the over-all structure or if anything should/must be rewritten entirely. Thanks!

Upvotes: 1

Views: 417

Answers (1)

Aracthor
Aracthor

Reputation: 5917

You just forgot to clear your window in your render loop:

do{

    glClear(GL_COLOR_BUFFER_BIT); // Clear background with clear color.
    glfwSwapBuffers(window);
    glfwPollEvents();

}
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
       glfwWindowShouldClose(window) == 0 );

glClear is often one of the first call of every render loop using OpenGL, giving you a new fresh frame to work on.

Upvotes: 4

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