A concave mirror

[buddhasystem]

Dear All,

Is there an easy way to add a concave mirror to a scene? If there is no easy way, what would be the optimal way to construct an OBJ file?

Thank you,
Maxim

[buddhasystem]

I've also tried to follow the recipe for the "wavy disk", except coding a rectangular coordinate grid and calculating a spherical surface truncated on the sides. For some reason, the mesh doesn't come out right, although there are no errors. The Python code seems simple enough:

N = 100

x_ = dr.linspace(mi.Float, -0.5, 0.5, N)
y_ = dr.linspace(mi.Float, -0.9, 0.9, N)

x=[]
y=[]
z=[]
for n in range(N):
    for m in range(N):
        z_ = 0.
        v = x_[n]**2+y_[m]**2
        if (v)<1.0:
            z_ = dr.sqrt(1-v)
        x.append(x_[n])
        y.append(y_[m])
        z.append(z_)

vertex_pos = mi.Point3f(x, y, z)

N1 = len(z)
M = N*N
# Move the last vertex to the center
#vertex_pos[dr.eq(dr.arange(mi.UInt32, M), M - 1)] = 0.0

# Generate the face indices
idx = dr.arange(mi.UInt32, M - 1)
face_indices = mi.Vector3u(M - 1, (idx + 1) % (M - 2), idx % (M - 2))

# Create an empty mesh (allocates buffers of the correct size)
mesh = mi.Mesh(
    "concave",
    vertex_count=M,
    face_count=M - 1,
    has_vertex_normals=False,
    has_vertex_texcoords=False,

[merlinND]

Hello @buddhasystem,

The simplest way to create meshes for use in Mitsuba is typically through Blender. You can then either export a single shape as OBJ or PLY, or alternatively use the mitsuba-blender add-on to export the whole scene at once.

[buddhasystem]

@merlinND Thank you. I've made a valiant effort to code this in FreeCAD but there are some bugs and inconsistencies, for example I couldn't just set a thickness to a segment of a sphere. I'll see if I have time to learn Blender...