Tutorials › dbc Classic › 6

Matrix terrain

A matrix is a grid of tiles whose corners you raise and lower: the classic way to build ground in DarkBASIC.

What you need

terrain.jpgexamples/dbc/tutorials/3d/

terrain.jpg is an atlas: four ground textures in a 2 × 2 grid.

Make the grid

MAKE MATRIX takes a number, the width and depth in world units, then the number of tiles across and deep. A matrix starts at its corner, so move it to centre it:

matrix_grid.dba excerptDownload

make matrix 1, 1000, 1000, 25, 25
position matrix 1, -500, 0, -500

Texture the tiles

PREPARE MATRIX TEXTURE cuts an image into tiles (here 2 × 2, numbered 1 to 4). FILL MATRIX gives every tile the same one; SET MATRIX TILE changes a single tile.

matrix_texture.dba excerptDownload

load image "terrain.jpg", 1
prepare matrix texture 1, 1, 2, 2
fill matrix 1, 0, 1

Shape the ground

RANDOMIZE MATRIX makes random bumps. SET MATRIX HEIGHT raises one corner. Nothing shows until you call UPDATE MATRIX, so make all your changes first.

matrix_shape.dba excerptDownload

randomize matrix 1, 30
set matrix height 1, 12, 12, 120
update matrix 1

Walk on it

GET GROUND HEIGHT returns the height at any point, in the matrix's own coordinates (from 0 to its size). Subtract the matrix's X and Z position from world coordinates before querying it. Here the matrix starts at −500, so use worldX + 500 and worldZ + 500. Add the matrix's Y position to the returned height if you have moved it vertically:

matrix.dbaDownload

rem Matrix terrain - OpenDBC tutorial (DarkBASIC Classic)
rem Media: terrain.jpg from examples/dbc/tutorials/3d
sync on : sync rate 60
autocam off
color backdrop rgb(170, 200, 230)
fog on : fog color rgb(170, 200, 230) : fog distance 1200

rem A 1000 x 1000 grid of 25 x 25 tiles
make matrix 1, 1000, 1000, 25, 25
position matrix 1, -500, 0, -500

rem Cut the texture into 2 x 2 tiles and use tile 1 everywhere
load image "terrain.jpg", 1
prepare matrix texture 1, 1, 2, 2
fill matrix 1, 0, 1

rem Hills: random heights, then a rocky mountain (tile 4) in the middle
randomize matrix 1, 30
for x = 10 to 15
   for z = 10 to 15
      set matrix height 1, x, z, 120
      set matrix tile 1, x, z, 4
   next z
next x
update matrix 1

rem A ball that rolls over the ground
make object sphere 1, 24
color object 1, rgb(255, 120, 40)

do
   a = wrapvalue(a + 1)
   bx# = sin(a) * 300 : bz# = cos(a) * 300
   rem get ground height works in matrix coordinates (0 to 1000)
   by# = get ground height(1, bx# + 500, bz# + 500)
   position object 1, bx#, by# + 6, bz#
   position camera sin(a - 15) * 400, by# + 60, cos(a - 15) * 400
   point camera bx#, by#, bz#
   sync
loop

Try this

See the grid with SET MATRIX WIREFRAME ON.
Make an endless landscape with SHIFT MATRIX UP.
Add a lake: a second, flat matrix with GHOST MATRIX ON.

The repository's landscape.dba does all three.