Object Representation Flashcards
What are the advantages of triangle meshes?
-Triangle intersection for ray-tracing is easy
- GPU is very efficient for rendering triangles
- Cam easily subdivide triangular meshes (for more levels of detail)
How many vertices are require to represent n triangles using triangular strips?
Triangular strips require n+2 vertices to represent n triangles.
What are the advantages for triangular strips?
- Compact storage, good for GPU transmissions
- Very efficient when drawing
- Reusable edge information during rendering
What is the disadvantage of triangular strips?
It’s not suited for all objects.
What does D3D_POINTLIST draw?
A list of isolated points (n vertices = n points)
What does D3D_LINELIST draw?
A list of isolated lines (2n vertices = n lines)
What does D3D_LINESTRIP draw?
Vertices that make a continuous line (n+1 vertices = n lines)
What does D3D_TRIANGELIST draw?
Group of 3 points defining an isolated triangle (3n vertices = n triangles)
What does a D3D_TRIANGLESTRIP draw?
Triangular strips (n+2 vertices = n triangles)
How are triangles made in triangle strips?
First three vertices 1 2 3 make and triangle, then 2 3 4 make the next and 3 4 5 and so on.
What is pointers to vertex list representation?
Each triangle vertex is a pointer to a 3D point.
What are the advantages of triangle list?
- Simple modelling
- Good for laser scanned objects not needing meshes
What are the disadvantages of triangle list?
- Occupies a lot of space
- Repeated vertices causing wasted calculations
What are the advantages of pointers to vertex list?
- Good compromise on space since vertices are not repeated
- Good for transformations
What are the disadvantages of pointers to vertex list?
- Requires extra memory
- Extra processing during modelling
