If the engine supports this, being able to draw 3D triangles would mean we could draw any 3D shape we want in the game dynamically! (with depth test support ofc, like drawLine3D, not drawIcon3D which has no depth test)

Sample syntax:

drawTriangle3D [p1, p2, p3, rgba, ...]

which draws a triangle with CCW vertex positions p1, p2, and p3. Thus the surface normal would be: (p2 - p1) x (p3 - p2) (or (p2 - p1) x (p3 - p1))

or a bit more advanced version:

drawTriangle3D [p1, p2, p3, ambientColor, diffuseColor, specularColor, specularIntensity]

which allows for basic phong shading as well :)

or an even more advanced version with texturing support:

drawTriangle3D [
   [p1, t1],
   [p2, t2],
   [p3, t3],
   "texture\path.paa",
   ambientColor, diffuseColor, specularColor, specularIntensity
]

where t1, t2, and t3 are normalized 2D texture coords.

Though I personally mostly need this for debugging purposes so even the first simple implementation will do! :)