Question

I'm trying to draw an Isocahedron in OpenGL with c++. I keep getting close but having some missing faces. I have found 3 different sets of vertex/index data on multiple sites, most often the data listed below

    float X = 0.525731112119133606f;
float Z = 0.850650808352039932f;
float temppts[12][3] = { { -X, 0.0f, Z }, { X, 0.0f, Z }, { -X, 0.0f, -Z }, { X, 0.0f, -Z },
{ 0.0f, Z, X }, { 0.0f, Z, -X }, { 0.0f, -Z, X }, { 0.0f, -Z, -X },
{ Z, X, 0.0f }, { -Z, X, 0.0f }, { Z, -X, 0.0f }, { -Z, -X, 0.0f } };  

GLushort tempindicies[60] = 
{ 1, 4, 0, 4, 9, 0, 4, 5, 9, 8, 5, 4, 1, 8, 4,
1, 10, 8, 10, 3, 8, 8, 3, 5, 3, 2, 5, 3, 7, 2,
3, 10, 7, 10, 6, 7, 6, 11, 7, 6, 0, 11, 6, 1, 0,
10, 1, 6, 11, 0, 9, 2, 11, 9, 5, 2, 9, 11, 2, 7};

This code is adapted from a book and multiple sites display it working, though they are drawing immediate and I'm using vbo/ibo. Can anyone point me to some working vertex/index data or tell me what is going wrong transferring this to buffer objects? The three different data all have differently incorrect icosahedrons, each with different faces missing.

I have checked over my bufferData calls many times and tried several drawing modes ( TRIANGLES, TRIANGLE_STRIP ... ) and am convinced the index data is wrong somehow

Was it helpful?

Solution

I used the mesh coordinates (vertices) and the triangle connectivity from Platonic Solids (scroll down to icosahedron). I've pasted a screen shot from that file below. When calling glDrawElements I used GL_TRIANGLES.

IcosahedronIcosahedron

Another thing to watch out for is back face culling. Initially switch off backface culling.

glDisable(GL_CULL_FACE);
Licensed under: CC-BY-SA with attribution
Not affiliated with StackOverflow
scroll top