Description

"Features" are things that are toggle-able, like "display snow flakes" or "display velocity" arrows. A feature should be toggleable via json (so it's starting state can be set) and (optionally) by a key.

Implementation

The test base should receive a json identifier on construction. Also, a "feature map" is given, mapping a feature name to feature data. This data includes:

• Name
• Optional key code
• Boolean value (state)

A key callback is registered to map the key codes to "toggle the boolean and issue a notification".

• Splatting should be done each frame, using an additive mode
• Left and right mouse should be splattable independently

Principle

We have to determine which voxels are "active" and ready to receive collisions. Those are voxels adjacent to a boundary.

More precisely, we now have two bits of information for boundaries (obstacles): Their snow density and their "activity". Initially, only obstacles have the active bit set. The snow density is zero everywhere. That way, the marching cubes algorithm doesn't produce any snow polygons, which is what we want.

At each time step, we update the grid's activity bits. A grid point counts as active if...

• it is either active itself
• or has a neighbor (Moore or Von Neumann, haven't decided) that is an obstacle (or has snow density above 1, see below)

We also update the obstacle bits at each time step. An obstacle is either already an obstacle or has a snow density above 1. This way, accumulated snow changes the wind velocity field. If we don't want that, we have to adapt the algorithm (see the above change).

Snow flakes fly around and change the snow density value by colliding with active cells. If that occurs, the snow density is increased by a constant amount.

Marching Cubes

Until I find a better way, the snow density is transferred to RAM at certain points in time and is triangulated using marching cubes.

Problems

• Transfer to RAM is slow (pinned memory, asynchronous transfers to the rescue?)
• Snow isn't avalancing (could be implemented though)

Sometimes, I involve the boundary where it doesn't make sense, for example:

(1 - boundary[this]) * velocity

Makes no sense because velocity is zero on the bounary, anyway.

The cursor should be set to exclusive while grabbing. Also, an indicator where the grabbing started whould be nice (maybe a dotted line connecting the starting point and the current position?).

Extract method?

They all have #ifndef FOO_HPP_INCLUDED instead of FOO_CL_INCLUDED

In 2D, the at, left_of, right_of etc. functions have to take two parameters: width and pitch.

List of typedefs

• cl::unique_kernel_ptr

Usage: Display current time modifier

Then, use this to calculate the absolute value of the vorticity, so that both vortex windings (cw and ccw) are visible.

-Ofast -flto -march=core2 seems to be broken, -O3 -march=core2 not.