OpenGL and VBO

[Angeljruiz]

Hey everyone,
I got this code:

#include <stdio.h>
#include <GL/glew.h>
#include <GLUT/glut.h>
#include "math_3d.h"
#include <stdlib.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, 0);

    glDrawArrays(GL_POINTS, 0, 1);

    glDisableVertexAttribArray(0);

    glutSwapBuffers();
}

void keypress(unsigned char key, int x, int y)
{
    switch (key) {
        case 27:
            exit(0);
            break;
            
        default:
            break;
    }
}


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

static void CreateVertexBuffer()
{
    Vector3f Vertices[1];
    Vertices[0] = Vector3f(0.0f, 0.0f, 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(640, 480);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Tutorial 02");

    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;
}

It just draws one dot in the middle of the screen as its suppose to using a vertex object. I was wondering how i could change the buffer after its already binded and stuff - I plan on making a function that adds boxes one at a time each time a key is pressed
Thanks in advance :)

EDIT:
Actually i think i mighta figured this out
Would this be acceptable?

#include <stdio.h>
#include <GL/glew.h>
#include <GLUT/glut.h>
#include "math_3d.h"
#include <stdlib.h>

GLuint VBO;
Vector3f Vertices[20];

int VBOSize = 4;




void AddBox()
{
    VBOSize += 4; //Will fix later
    Vertices[4] = Vector3f(-2.0f, -1.0f, -10.0f);
    Vertices[5] = Vector3f(-2.0f, 1.0f, -10.0f);
    Vertices[6] = Vector3f(0.0f, 1.0f, -10.0f);
    Vertices[7] = Vector3f(0.0f, -1.0f, -10.0f);
    
    
	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
}

void handleResize(int w, int h) {
	//Tell OpenGL how to convert from coordinates to pixel values
	glViewport(0, 0, w, h);
	
	glMatrixMode(GL_PROJECTION); //Switch to setting the camera perspective
	
	//Set the camera perspective
	glLoadIdentity(); //Reset the camera
	gluPerspective(45.0,                  //The camera angle
				   (double)w / (double)h, //The width-to-height ratio
				   1.0,                   //The near z clipping coordinate
				   200.0);  
}
void keypress(unsigned char key, int x, int y)
{
    switch (key) {
        case 27:
            exit(0);
            break;
            
        default:
            AddBox();
            glutPostRedisplay();
            break;
    }
}

static void RenderSceneCB()
{
    glClear(GL_COLOR_BUFFER_BIT);
    
    glEnableVertexAttribArray(0);
    glBindBuffer(GL_ARRAY_BUFFER, VBO);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
    
    glDrawArrays(GL_QUADS, 0, VBOSize);
    
    glDisableVertexAttribArray(0);
    
    glutSwapBuffers();
}


static void InitializeGlutCallbacks()
{
    glutDisplayFunc(RenderSceneCB);
    glutKeyboardFunc(keypress);
    glutReshapeFunc(handleResize);
}

static void CreateVertexBuffer()
{
    Vertices[0] = Vector3f(1.0f, -1.0f, -10.0f);
    Vertices[1] = Vector3f(1.0f, 1.0f, -10.0f);
    Vertices[2] = Vector3f(3.0f, 1.0f, -10.0f);
    Vertices[3] = Vector3f(3.0f, -1.0f, -10.0f);

    
 	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(640, 480);
    glutInitWindowPosition(100, 100);
    glutCreateWindow("Box test");
    
    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;
}

[Angeljruiz]

Bump