Interleaved Vertex Array Object doesn't show colors

Question

I am trying to render a bunch of vertices with an own color for each vertex. The number of vertices is around 1 mio, so I use a Vertex Array Object to render them. It's no problem for me to render the points, but when I add the colors to the data array the points are still rendered white. I tried different tutorials I found, but they all didn't work for me ( like: tut1, tut2 or this ).

I have the data in one array with VCVCVC... 3 floats for the vertex position and 4 floats for the color.

glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);

unsigned VAO_ID;
glGenVertexArrays(1, &VAO_ID);
glBindVertexArray(VAO_ID);

unsigned VBO_ID;
glGenBuffers(1, &VBO_ID);

glBindBuffer(GL_ARRAY_BUFFER, VBO_ID);
glBufferData(GL_ARRAY_BUFFER, vertex_count*7*4, vertices, GL_STATIC_DRAW);

glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 7*4, 0);
glEnableVertexAttribArray(0);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 7*4, (char*)NULL + 3);
glEnableVertexAttribArray(1);

glVertexPointer(3, GL_FLOAT, 7*4, &vertices[0]);
glColorPointer(4, GL_FLOAT, 7*4, &vertices[3]);

glDrawArrays(GL_POINTS, 0, vertex_count);

I am new to OpenGL, so it is possible that I made a stupid mistake that I can't see.

BTW: the vertex locations are still correct even with the colors in the array

Answer 1

Pick one and only one method of vertex submission:

1. Vertex arrays (VA):

   glEnableClientState(GL_VERTEX_ARRAY);
   glEnableClientState(GL_COLOR_ARRAY);
   
   glVertexPointer(3, GL_FLOAT, 7*4, &vertices[0]);
   glColorPointer(4, GL_FLOAT, 7*4, &vertices[3]);
   
   glDrawArrays(GL_POINTS, 0, vertex_count);
   

2. Vertex buffer object (VBO):

   unsigned VBO_ID;
   glGenBuffers(1, &VBO_ID);
   glBindBuffer(GL_ARRAY_BUFFER, VBO_ID);
   glBufferData(GL_ARRAY_BUFFER, vertex_count*7*4, vertices, GL_STATIC_DRAW);
   
   glEnableClientState(GL_VERTEX_ARRAY);
   glEnableClientState(GL_COLOR_ARRAY);
   
   glVertexPointer(3, GL_FLOAT, 7*4, 0);
   glColorPointer(4, GL_FLOAT, 7*4, (char*)NULL + 3);
   
   glDrawArrays(GL_POINTS, 0, vertex_count);
   

3. Vertex array object (VAO) + VBO (requires corresponding shaders):

   unsigned VAO_ID;
   glGenVertexArrays(1, &VAO_ID);
   glBindVertexArray(VAO_ID);
   
   unsigned VBO_ID;
   glGenBuffers(1, &VBO_ID);
   glBindBuffer(GL_ARRAY_BUFFER, VBO_ID);
   glBufferData(GL_ARRAY_BUFFER, vertex_count*7*4, vertices, GL_STATIC_DRAW);
   
   glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 7*4, 0);
   glEnableVertexAttribArray(0);
   glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 7*4, (char*)NULL + 3);
   glEnableVertexAttribArray(1);