CODEWITHSUNDEEP
copengl
tambalolo
tambalolo

Reputation: 1065

OpenGL triangle not showing

I'm currently following a tutorial on modern OpenGL. I copied a code from the said tutorial and tried it. The code below should display a triangle but only a blank window appears. I tried the tutorial before this one in which a point appears on the screen and it worked but this one does not work. What could be the problem?

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

GLuint VBO;

static void RenderSceneCB()
{
    glClear(GL_COLOR_BUFFER_BIT);
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);

    glDrawArrays(GL_TRIANGLES, 0, 3);

    glDisableVertexAttribArray(0);

    glutSwapBuffers();
}

static void InitializeGlutCallbacks()
{
    glutDisplayFunc(RenderSceneCB);
}

static void CreateVertexBuffer()
{
    static const GLfloat Vertices[] = {
        -1.0f, -1.0f, 0.0f,
        1.0f, -1.0f, 0.0f,
        0.0f,  1.0f, 0.0f,
    };

    glGenBuffers(1, &VBO);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
}

int main(int argc, char** argv)
{
    glutInit(&argc, argv);
    glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA);
    glutInitWindowSize(1024, 768);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Tutorial 03");

    InitializeGlutCallbacks();

    // Must be done after glut is initialized!
    GLenum res = glewInit();
    if (res != GLEW_OK) {
        fprintf(stderr, "Error: '%s'\n", glewGetErrorString(res));
        return 1;
    }

    glClearColor(0.0f, 0.0f, 0.0f, 0.0f);

    CreateVertexBuffer();

    glutMainLoop();

    return 0;
}

Upvotes: 0

Views: 1053

Answers (2)

Sean Reichel
Sean Reichel

Reputation: 1

I ran into this problem myself on Ubuntu 12.04. This problem can also occur if you do not have a current graphics driver installed, as it will try to use OpenGL 1.x. Update your video driver so that your system uses modern OpenGL and try it again.

As far as I know, the lack of shaders isn't a problem because it "should" utilize default shaders automatically. Though that might just be me.

Upvotes: 0

Nicol Bolas
Nicol Bolas

Reputation: 473407

I see no evidence of any shaders. And you can't use glVertexAttribPointer without shaders.

The tutorial you copy-and-pasted this code from probably had shaders in it somewhere. You should use them.

Upvotes: 1

Related Questions