How to output a ".tiff" image in 3d mesh in OpenGL.

OpenGL OpenGL: Basic Coding
1 

for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            glVertex3f(x_pos[j], y_pos[i], z);
            glColor3ub(image_p[k + 2], image_p[k + 1], image_p[k]);
            k++;
        }
    }

I randomly put the height value (z value).
However, it does not form a 3d mesh on the screen.
How do you convert an imported image to a 3d mesh?
please help me
Thank you

2

In this old, deprecated method of sending vertices to the GPU (called OpenGL immediate mode), for each vertex, you set all vertex attributes besides position first (e.g. glColor*()), and then register the vertex position (glVertex*()). That latches all of the registered vertex attributes for that vertex and gets ready for the next vertex.

In other words, swap your glVertex3f() and glColor3ub() lines.

3

Thank you very much
Should I use a triple for statement to form a mesh with z values?
ex)
for (int x = 0; x < height; x++)
{
for (int y = 0; y < width; y++)
{
for (int z = 0; z < width; z++)
{
}
}
}

4

No, you would just feed vertex z with your height data. Another a loop would be for volumetric data not a surface with height. Using your approach to draw an image is massively inefficient and is what you might call “micropolygons”, I used this technique before texture hardware was a thing, but for your needs you could draw one quad with a single texture applied to it instead of per vertex coloring and a vertex for each image sample.

5

To draw a mesh you must also input a series of points in an order suited to the primitive type you intend to draw. For GL_POINTS you would just touch every vertex once, for a surface you need to issue the points to create a triangle that fills the space between points. w*h is not enough, and for a GL_TRIANGLE_STRIP for example you need to issue 2 vertices for each triangle, spanning outer_loop increment to outer_loop+1. Then handle the switch back to inner loop reset either with degenerates or primitive input restart (a new glBegin).

This makes it usefully clear:

http://www.learnopengles.com/tag/triangle-strips/