Each Vector Grid is made up of a rectangular grid of points, with each point connected by springs to its vertical and horizontal neighbors. When a point is moved from its starting position, it will drag its neightbours with it, thereby causing a cascading effect that causes the entire grid to dynamically deform.
In addition to this, certain
points are also attached by springs to their starting position, causing them to
naturally return to their default position provided no other forces are acting
on them, which helps to maintain the overall shape of the grid.
Creating
a Vector Grid
To create a Vector Grid, simply go
to the main Unity menu bar and choose GameObject->Create Other->Vector
Grid->Vector Grid. Alternatively, you can attach a Vector Grid component to
an existing GameObject using the Component->Vector Grid menu.
Applying
Forces
Forces can be applied using the
VectorGrid.AddGridForce() functions. These functions requires a force position,
force strength, and force radius - the force is applied to every grid point
that falls within the sphere defined by the position and radius (with the force
amount reducing linearly towards the edges of the sphere).
You can choose to provide either a
float force value (in which case the force is treated as an omin-directional
force emanating from the force centre) or as a vector (in which case each grid
point is pushed in the direction defined by the vector). Forces can also
(optionally) provide colour values, which will alter the color of all points
that are within the force radius.
Forces can also be applied by
attaching a VectorGridForce component to any GameObject, which will cause a
force to be constantly applied to the associated VectorGrid from the
GameObject's position.
Forces can produce different
visual effects depending on whether they are applied on a 2D plane or not (ie.
the Z position of the force is the same as that of the grid points). 2D forces
cause grid points to 'bunch up' around the edge of the force radius, whereas 3D
forces generally cause smoother waves as the points are also able to extend
along the Z axis.
Scrolling
The Grid
Vector Grids can also be scrolled,
allowing you to effectively create the illusion of an infinitely size Vector
Grid. The code achieves this by recycling grid points from the opposite side of
the grid to the direction in which it is being scrolled (ie. scrolling left
will destroy grid points on the far right hand side, and vice versa). The
advantage of this is that the code generates no garbage since no additional
allocations are required once the initial grid has been configured. However,
since there is no guarantee made that a grid point is not still on-screen when
it is re-used, it is recommended to configure the grid to be larger than the
visible screen space so that the user cannot see points being added or removed.
To scroll the grid, simply use the
Scroll() function to scroll by a given distance. Alternatively, you can make
use of the 'Tracked Camera' field in the inspector to automatically scroll the
Grid as your game camera moves.
Freshly generated rows/columns
will have their colors reset, so you can dynamically modify the grid's Thick
Line Spawn Color/Thin Line Spawn Color variables to create a grid that appears
to change color as it scrolls.
Performance
The Vector Grid code has been
written with performance in mind, but ultimately the CPU cost will primarily be
determined by the configuration of the grid that you are using. Bigger grids
mean that the code needs to simulate more points and springs, and also that
applied forces need to check over a larger array of points in order to
determine which ones to affect. Reducing the grid dimensions should be your
first port of call if you wish to improve performance. Also, be careful when
using the Grid Smoothing Factor value, as this can drastically increase the
number of triangles and vertices that the grid needs to render.
Inspector
Settings
Grid Width/Grid Height
The dimensions of the grid
Grid Scale
The horizontal/vertical spacing
between grid points
Max Fog Distance/Max Fog Alpha
Scale
When grid points move along the
Z-axis they can optionally be faded out,
which causes 'holes' to appear in the grid around areas of high force.
Max Fog Distance controls the distance at which this effect is the strongest,
and Max Fog Alpha Scale controls how much the alpha value is altered at this
distance (1 meaning no change, 0 meaning totally transparent).
Two Way Fog
By default, fog is only applied
when grid points move downwards on the Z-axis, but you can optionally also fade
them out when they move forwards along the axis.
Render Mode
You can choose to render any
Vector Grid as a plane rather than as a grid mesh, meaning that the applied
material will be stretched to cover the entire mesh rather than being applied
to each individual vertical/horizontal connector. This may prove useful if you
wish to use a Vector Grid to simulate eg. a pool of water.
Vector Grid Point Mass
Controls how heavy each grid point
is. Adjusting this will alter the behaviour of the springs.
Velocity Damping
This controls how much velocity
each grid point loses every frame - ie. it controls the rate of deceleration.
Lower values will cause grid points to continue moving for longer after a point
is applied.
Thick Line Spawn Color/Thin Line
Spawn Color/Thick
Line Width /Thin Line Width/Thick Line Spacing/Thick Line Spacing
The grid can be set to spawn
alternating thin and thick lines, with different colors and widths. These
values control the starting color of the lines, their width, and how frequently
thick lines appear vs. thin ones.
Spring Stiffness/Spring Damping
Used to control the strength and
oscillation damping of the springs that connect each grid point to its
neighbors.
Edge Spring Stiffness/Edge
Spring Damping
Points around the edge of the grid
are anchored to their starting position in order to preseve the outline of the
grid. These values control the strength and oscillation damping of these
springs.
Clamp Edges
Optionally, you can set the points
around the edge of the grid to be completely static, and unaffected by any
force.
Loose Spring Stiffness/Loose
Spring Damping
Loose springs are placed on
certain grid points in order to anchor them to their starting positions. This
means that they will naturally return to their starting position over time, and
therefore maintain the overall shape of the grid. These values control the
strength and oscillation damping of these springs.
Loose Spring Interval
Controls how often loose springs
are generated. eg. A value of 3 means that a loose spring will be placed at the
intersection of every 3rd row and 3rd column. Altering this value can make the
overall grid more or less stable.
Rest Distance Scalar
Each spring tries to the two grid
points attached to it at a certain distance from one another. By default, this
is just the distance that they were before any forces were applied, but the
Rest Distance Scalar value allows you to scale this down, effectively creating
a more taut grid.
Grid Smoothing Factor
Controls how many subdivisions are
generated on the line connecting a grid point and its neighbor. The mesh
rendering uses Catmull-Rom interpolation to generate curved lines connecting
the points, resulting in smoother deformations at the expense of more
vertices/triangles and CPU cost.
Debug Draw
Turns on debug drawing - renders
the mesh using basic debug lines.
Calculate Normals
Turn this on if you need normals
to be calculated for the mesh
Tracked Camera
Assign a camera to this field and
the mesh will automatically scroll to match the movement of the camera.
Parallax Scroll
When using a tracked camera, this
value controls whether the grid will scroll faster or slower than the camera's
movement, providing a parallax effect.
Allow Horizontal Scroll/Allow
Vertical Scroll
Allows you to disable horizontal
or vertical scrolling if eg. you are using a tracked camera and only wish the
grid to be able to scroll in a single direction.
Enable Diagnostics
Enable update time diagnostics -
displays some debug info about CPU usage in the scene view.
