Visual Studios 2012 RGB cube displaying black cube - c++

Question

I'm just starting out using visual studios and C++ and I've been following along the examples in Ed Angel's Interactive Computer Graphics book. I've seem to come into a snag with the rotating RGB cube example. I followed along exactly and I have got it to run and display a cube but the cube is all black instead of colored. To my understanding everything is correct and I have haven't been able to find any suggestions or hints as to what went wrong from google searches. I was wondering if anyone here with much more experience than I have could help me figure out what happened or point me in the direction.
// Display a rotating color cube
#include "Angel.h"
typedef Angel::vec4 color4;
typedef Angel::vec4 point4;
const int NumVertices = 36;
point4 points[NumVertices];
color4 colors[NumVertices];
//Vertices of a unit cube centered at origin, sides aligned with axes
point4 vertices[8] = {
point4( -0.5, -0.5, 0.5, 1.0),
point4( -0.5, 0.5, 0.5, 1.0),
point4( 0.5, 0.5, 0.5, 1.0),
point4( 0.5, -0.5, 0.5, 1.0),
point4( -0.5, -0.5, -0.5, 1.0),
point4( -0.5, 0.5, -0.5, 1.0),
point4( 0.5, 0.5, -0.5, 1.0),
point4( 0.5, -0.5, -0.5, 1.0)
};
//RGBA colors
color4 vertex_colors[8] = {
color4( 0.0, 0.0, 0.0, 1.0), //black
color4( 1.0, 0.0, 0.0, 1.0), //red
color4( 1.0, 1.0, 0.0, 1.0), //yellow
color4( 0.0, 1.0, 0.0, 1.0), //blue
color4( 0.0, 0.0, 1.0, 1.0), //green
color4( 1.0, 0.0, 1.0, 1.0), //magenta
color4( 1.0, 1.0, 1.0, 1.0), //white
color4( 0.0, 1.0, 1.0, 1.0) //cyan
};
//Array of rotation angles (in degrees) for each coordinate axis
enum { Xaxis = 0, Yaxis = 1, Zaxis = 2, NumAxes = 3 };
int Axis = Xaxis;
GLfloat Theta[NumAxes] = { 0.0, 0.0, 0.0};
GLuint theta; //The location of the "theta" shader uniform variable
//----------------------------------------------------------------------------
//quad generates two triangles for each face and assigns colors to the vertices
int Index = 0;
void
quad( int a, int b, int c, int d)
{
colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
colors[Index] = vertex_colors[b]; points[Index] = vertices[b]; Index++;
colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
colors[Index] = vertex_colors[d]; points[Index] = vertices[d]; Index++;
}
//----------------------------------------------------------------------------
//generate 12 triangles: 36 vertices and 36 colors
void
colorcube( void )
{
quad( 1, 0, 3, 2);
quad( 2, 3, 7, 6);
quad( 3, 0, 4, 7);
quad( 6, 5, 1, 2);
quad( 4, 5, 6, 7);
quad( 5, 4, 0, 1);
}
//----------------------------------------------------------------------------
//OpenGL initialization
void
init( void )
{
colorcube();
//Create a vertex array object
GLuint vao;
glGenVertexArrays( 1, &vao );
glBindVertexArray( vao );
//Create and initialize a buffer object
GLuint buffer;
glGenBuffers( 1, &buffer );
glBindBuffer( GL_ARRAY_BUFFER, buffer );
glBufferData( GL_ARRAY_BUFFER, sizeof(points) + sizeof(colors), NULL, GL_STATIC_DRAW );
glBufferSubData( GL_ARRAY_BUFFER, 0, sizeof(points), points );
glBufferSubData( GL_ARRAY_BUFFER, sizeof(points), sizeof(colors), colors );
//Load shaders and use the resulting shader program
GLuint program = InitShader( "vshader36.glsl", "fshader36.glsl" );
std::cout << "Program ID:" <<program;
glUseProgram ( program );
//set up vertex arrays
GLuint vPosition = glGetAttribLocation( program, "vPosition" );
glEnableVertexAttribArray( vPosition );
glVertexAttribPointer( vPosition, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(sizeof(points)) );
theta = glGetUniformLocation( program, "theta" );
glEnable( GL_DEPTH_TEST );
glClearColor( 1.0, 1.0, 1.0, 1.0 );
}
//----------------------------------------------------------------------------
void
display( void )
{
glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
glUniform3fv( theta, 1, Theta );
glDrawArrays( GL_TRIANGLES, 0, NumVertices );
glutSwapBuffers();
}
//----------------------------------------------------------------------------
void
keyboard( unsigned char key, int x, int y )
{
switch ( key ) {
case 033:
case 'q': case 'Q':
exit( EXIT_SUCCESS );
break;
}
}
//----------------------------------------------------------------------------
void
mouse( int button, int state, int x, int y )
{
if ( state == GLUT_DOWN ) {
switch( button ) {
case GLUT_LEFT_BUTTON: Axis = Xaxis; break;
case GLUT_MIDDLE_BUTTON: Axis = Yaxis; break;
case GLUT_RIGHT_BUTTON: Axis = Zaxis; break;
}
}
}
//----------------------------------------------------------------------------
void
idle( void )
{
Theta[Axis] += 0.01;
if ( Theta[Axis] > 360.0 ) {
Theta[Axis] -= 360.0;
}
glutPostRedisplay();
}
//----------------------------------------------------------------------------
int
main( int argc, char **argv )
{
glutInit(&argc, argv);
glutInitDisplayMode( GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH );
glutInitWindowSize( 512, 512 );
glutCreateWindow( "Color Cube" );
glewInit();
init();
glutDisplayFunc( display );
glutKeyboardFunc( keyboard );
glutMouseFunc( mouse );
glutIdleFunc( idle );
glutMainLoop();
return 0;
}
fshader36.glsl
#version 150
in vec4 color;
out vec4 fColor;
void main()
{
fColor = color;
}
vshader36.glsl
#version 150
in vec4 vPosition;
in vec4 vColor;
out vec4 color;
uniform vec3 theta;
void main()
{
vec3 angles = radians( theta );
vec3 c = cos( angles );
vec3 s = sin( angles );
mat4 rx = mat4( 1.0, 0.0, 0.0, 0.0,
0.0, c.x, -s.x, 0.0,
0.0, s.x, c.x, 0.0,
0.0, 0.0, 0.0, 1.0 );
mat4 ry = mat4( c.y, 0.0, s.y, 0.0,
0.0, 1.0, 0.0, 0.0,
-s.y, 0.0, c.y, 0.0,
0.0, 0.0, 0.0, 1.0 );
mat4 rz = mat4( c.z, -s.z, 0.0, 0.0,
s.z, c.z, 0.0, 0.0,
0.0, 0.0, 1.0, 0.0,
0.0, 0.0, 0.0, 1.0 );
color = vColor;
gl_Position = rz * ry * rx * vPosition;
}

Answer 1

You have to actually set vColor for it to have a valid value. Do the same thing that you did to set vPosition:
GLuint vColor= glGetAttribLocation( program, "vColor" );
glEnableVertexAttribArray( vColor);
glVertexAttribPointer( vColor, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(sizeof(colors)) );

Answer 2

You don't actually pass any colour information to your shader.