I think MeshLab may be able to make winding order consistent.

These libs will give you access to uncompressed pixels if you need to modify the image. You really don't want to write your own jpeg decoder...

Insert a plane textured with your image in your favorite modeling program. Start laying down triangles on top.

You could encode a palette in a 1 dimensional texture and use the gray value to look up a color. Or you could procedurally define a palette using math functions like smoothstep or something.

Now try g++ -o tst test.c -lGL -lglut

Are bots posting these? What is the point?

This will only work if the mesh is convex.

Is there an .mtl file? It is possible that there is a scale applied to the texture which is specified in the material.

You are running inside a VMware virtual machine.

Cubic Hermite spline. Set the end points to the vertices of the base, and the slopes parallel with the triangle edges.

glut.h includes gl.h and glu.h