CODEWITHSUNDEEP
openglc++11
user3064869
user3064869

Reputation: 530

glClear sometimes works and sometimes doesn't

I have very simple openGL code:

screen.cpp

#include <GL/glew.h>
#include <GL/freeglut.h>
#include <GL/gl.h>

#include <iostream>

#define WIDTH 683
#define HEIGHT 384

void init() {
    glClearColor(1.0f, 1.0f, 1.0f, 0.0f);
}

void display() {
    glClear(GL_COLOR_BUFFER_BIT);
    glutSwapBuffers();
}

int main(int argc, char* argv[]) {
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
    glutInitWindowSize(WIDTH, HEIGHT);
    glutCreateWindow("test");
    glutDisplayFunc(display);

    GLenum res = glewInit();
    if (res != GLEW_OK) {
        std::cout<<"Error: "<<glewGetErrorString(res)<<std::endl;
        return 1;
    }

    init();
    glutMainLoop();

    return 0;
}

The wierd thing is this code sometimes works and sometimes doesn't. I expect to get a white blank screen, and when I run this program, randomly and more frequently, I would just get transparent screen showing what was there before the program was run. Sometimes the program works correctly and shows me a blank white screen. What is the problem?

compiled with: g++ -o screen screen.cpp -g -Wall -std=c++11 -lGLEW -lglut -lGL

Upvotes: 1

Views: 501

Answers (1)

ratchet freak
ratchet freak

Reputation: 48186

it's the alpha you specify in clearColor, 0 means transparent, change it to 1 and it will be a proper blank screen.

Upvotes: 1

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