OpenGl not rendering .obj files correctly - c++

Question

I have been given the task of importing an obj file and loading it up in C++.
Its loading the file correctly but displainy it incorrectly. Can anybody see anything wrong with my setup of opengl stuff? :)
Here is a picture of what the render looks like atm
#define _USE_MATH_DEFINES
#include<stdio.h>
#include <GL/glew.h>
#include <GL/glut.h>
#include "InitShader.h"
#include <math.h>
#include "MatrixStack.h"
#include "Object.h"
#include <time.h>
#define BUFFER_OFFSET( offset ) ((GLvoid*) (offset))
float x = 1.0;
const int NumVertices = 144;
const int NumIndicies = 104;
GLfloat vertices[NumVertices];
// RGBA olors
GLfloat vertexColours[NumVertices];
// each entry is an index into the vertices matrix
GLint vertexIndicies[NumIndicies];
//GLfloat vertices2[NumVertices];
// RGBA olors
//GLfloat vertexColours2[NumVertices];
// each entry is an index into the vertices matrix
//GLint vertexIndicies2[NumIndicies];
GLuint vao;
GLuint program;
GLuint buffers[2];
GLfloat radius = 1.0;
GLfloat theta = 0.0;
GLfloat phi = 0.0;
const GLfloat dr = 5.0 * M_PI/180.0;
// Projection transformation parameters
GLfloat left2 = -1.0, right2 = 1.0;
GLfloat bottom = -1.0, top = 1.0;
GLfloat zNear = 0.5, zFar = 3.0;
GLuint modelView; // model-view matrix uniform shader variable location
GLuint projection; // projection matrix uniform shader variable location
MatrixStack modelViewStack(5);
MatrixStack projectionStack(5);
// OpenGL initialization
void
init()
{
srand ( time(NULL) );
Object myst("assignment1.obj");
float *tempFloat = myst.verts();
float *tempFloat2 = myst.indis();
for (unsigned int i=0; i<NumVertices; vertices[i]=tempFloat[i],i++);
for (unsigned int i=0; i<NumIndicies; vertexIndicies[i]=tempFloat2[i],i++);
for (unsigned int i=0; i<NumVertices;i++){
float a = (float)(rand()%10);
a = a/10;
cout << a;
vertexColours[i]=a;
}
for (unsigned int i=0; i<NumVertices; cout << vertices[i] << endl ,i++);
for (unsigned int i=0; i<NumIndicies; cout << vertexIndicies[i] << endl ,i++);
glEnable( GL_DEPTH_TEST );
//make background yerpul in colour
glClearColor( 0.235, 0.194, 0.314, 1.0 );
// Load shaders and use the resulting shader program
program = InitShader( "vshader41.glsl", "fshader41.glsl" );
glUseProgram( program );
// Create a vertex array object
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
// Create and initialize two buffer objects
glGenBuffers( 2, buffers);
//one buffer for the vertices and colours
glBindBuffer( GL_ARRAY_BUFFER, buffers[0]);
glBufferData( GL_ARRAY_BUFFER, sizeof(vertices) + sizeof(vertexColours),NULL, GL_STATIC_DRAW );
glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(vertices), vertices );
glBufferSubData( GL_ARRAY_BUFFER, sizeof(vertices), sizeof(vertexColours), vertexColours);
//one buffer for the indices
glBindBuffer( GL_ELEMENT_ARRAY_BUFFER, buffers[1]);
glBufferData( GL_ELEMENT_ARRAY_BUFFER, sizeof(vertexIndicies),vertexIndicies, GL_STATIC_DRAW );
// set up vertex arrays
GLuint vPosition = glGetAttribLocation( program, "vPosition" );
glEnableVertexAttribArray( vPosition );
glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0) );
GLuint vColor = glGetAttribLocation( program, "vColor" );
glEnableVertexAttribArray( vColor );
glVertexAttribPointer( vColor, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(sizeof(vertices)) );
modelView = glGetUniformLocation( program, "model_view" );
projection = glGetUniformLocation( program, "projection" );
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glBindVertexArray(0);
}
//----------------------------------------------------------------------------
void
display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
modelViewStack.loadIdentity();
modelViewStack.lookAt(radius*sin(theta)*cos(phi),
radius*sin(theta)*sin(phi),
radius*cos(theta),
0.0,0.0,0.0,
0.0,1.0,0.0);
glUniformMatrix4fv(modelView, 1, GL_FALSE, modelViewStack.getMatrixf());
projectionStack.loadIdentity();
projectionStack.ortho(left2,right2,bottom,top,zNear,zFar);
glUniformMatrix4fv(projection, 1, GL_FALSE, projectionStack.getMatrixf());
glBindVertexArray(vao);
glBindBuffer(GL_ARRAY_BUFFER, buffers[0]);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, buffers[1]);
//Indexing into vertices we need to use glDrawElements
glDrawElements (GL_TRIANGLES, NumIndicies, GL_UNSIGNED_INT, 0);
glutSwapBuffers();
}
//----------------------------------------------------------------------------
void keyboard( unsigned char key, int x, int y )
{
switch( key ) {
case 033: // Escape Key
case 'q': case 'Q':
exit( EXIT_SUCCESS );
break;
case 'x': left2 *= 1.1; right2 *= 1.1; break;
case 'X': left2 *= 0.9; right2 *= 0.9; break;
case 'y': bottom *= 1.1; top *= 1.1; break;
case 'Y': bottom *= 0.9; top *= 0.9; break;
case 'z': zNear *= 0.9; zFar *= 1.1; break;
case 'Z': if (zNear<zFar){zNear *= 1.1; zFar *= 0.9;} break;
case 'r': radius *= 2.0; break;
case 'R': radius *= 0.5; break;
case 'o': theta += dr; break;
case 'O': theta -= dr; break;
case 'p': phi += dr; break;
case 'P': phi -= dr; break;
case ' ': // reset values to their defaults
left2 = -1.0;
right2 = 1.0;
bottom = -1.0;
top = 1.0;
zNear = -1.0;
zFar = 1.0;
radius = 1.0;
theta = 0.0;
phi = 0.0;
break;
}
glutPostRedisplay();
}
//----------------------------------------------------------------------------
void idle(){
theta += .001;
left2 += .0001;
glutPostRedisplay();
}
//----------------------------------------------------------------------------
void
reshape( int width, int height )
{
glViewport( 0, 0, width, height );
}
//----------------------------------------------------------------------------
int
main( int argc, char **argv )
{
glutInit( &argc, argv );
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
glutInitWindowSize( 512, 512 );
glutCreateWindow( "Orbit the Color Cube - Orthographic" );
glewInit();
init();
glutIdleFunc(idle);
glutDisplayFunc( display );
glutKeyboardFunc( keyboard );
glutReshapeFunc( reshape );
glutMainLoop();
return 0;
}

Answer 1

The vertex indexes of the faces in the .obj file starts at 1, not 0 as might be expected. Try to decrease each index with 1 when you load the file. If I read your code correctly, this line:
for (unsigned int i=0; i<NumIndicies; vertexIndicies[i]=tempFloat2[i],i++);
should be
for (unsigned int i=0; i<NumIndicies; vertexIndicies[i]=tempFloat2[i] - 1,i++);