TheGameCreators - CodeBase - Ye olde water algorithm Mk. 2

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Category: 3D Effects

Version: 1.1

Information

Uploaded: 10th May 2005 23:48

Modified: 15th May 2005 19:53

Author: Tinkerer

Summary

An old and well-known water effect, plus quick and dirty normals calculation.

Full Description

Quick and dirty normals calculation used to illuminate the matrix from three light sources. Spacebar selects matrix behaviour, mouse2 selects interference type, and mouse1 affects interference amount. The basic principle of the algorithm is surprisingly simple, with the main part being only four lines long. Two two-dimensional arrays are set up with zero values. The algorithm runs over every element in the first array and does this: For each element in the first array... Get the value of the four horizontal and vertical elements adjoining the current element in the second two-dimensional array space, divided by two. Remove from this value, the value of the current element in the first array. Apply the result to the current element in the first array. Multiply the value of the current element in the first array by a damping value of less than one. Repeat for all elements. The data in the two arrays is then swapped, and the cycle repeats. If a non-zero value is placed into an array, waves of non-zero values will propagate outwards from the point of interference, reflecting from the edge elements of the arrays. If an array is then used as the height information for a matrix object, that matrix will display the patterns as water-like waves. Because of the damping value, the interference will gradually appear to dissipate, eventually leaving a flat landscape of zero values. <update 1.1> Code generally tidied up and optimised. The memory foam effect is no longer a broken water effect. Even more remarks added. That's about it for this script until I embed it in a function and use it in something bigger. Known bugs: This algorithm only approximates a wave-like effect on a 2D map. It isn't precise, but it's precise enough for computer games. If excessive interference is introduced into the arrays, the result can be chaotic at best. High-frequency waves will also not be rendered well. In this particular script's case, flicking rapidly between water and memory foam matrix behaviours can generate increasingly large values in the arrays. The workaraound is to be patient and let the values decrease.

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

rem Set sync up.

sync on : sync rate 30

rem Hide the mouse pointer.

hide mouse

rem Declare the two arrays that will be used to hold height information.

dim imgbuffer1(1024, 1024) AS FLOAT

dim imgbuffer2(1024, 1024) AS FLOAT

rem Make this as big as your system can handle!

gridsize = 128

rem This value determines how large the matrix will be rendered.

gridmultiplier = 8

rem Fill the arrays with zeros.

for z = 0 to gridsize + 1

for x = 0 to gridsize + 1

imgbuffer1(x, z) = 0.0

imgbuffer2(x, z) = 0.0

next x

next z

rem Create a set of vectors that will be used to calculate the normal of

rem each matrix tile.

for vc = 1 to 6

rtmp = make vector3(vc)

set vector3 vc, 0.0, 0.0, 0.0

next vc

rem Determine where the middle of the matrix will be

middle = gridsize / 2

rem Set this to a value BELOW ZERO. Or don't and enjoy the fireworks.

rem 0.90 to 0.99 are "sensible" values.

damping AS FLOAT

damping = 0.96

rem Making this higher will slow the wave frequency of the mouse+sine effect.

wavefreq AS FLOAT

wavefreq = 2

rem Adjusting these two variables will determine how much mouse button 1 affects

rem the interference generators.

lowheight = 10

highheight = 100

rem You can customize your own water behaviour using the above three variables together

rem The current pattern value is stored here

pattern AS INTEGER

pattern = 0

rem The current algorithm (water or mousepad foam)

mtype = 0

rem The next two variables are used together to stop the pattern changing in a loop when

rem mouse 2 is held down.

clik AS INTEGER

clik = 0

lastclik AS INTEGER

lastclik = 0

rem The next two variables are used together to stop the matrix behaviour changing in a

rem loop when the spacebar is held down.

lastspace = 0

space = 0

rem A temporary variable. Used later on.

tmp AS FLOAT

rem Current mouse position and mouse+sine wave generator height go here.

mouseposx AS INTEGER

mouseposz AS INTEGER

waveheight AS INTEGER

waveheight = lowheight

rem Load matrix texture here.

MImg = 1 : load image "wtex2.jpg", MImg

rem Calculate matrix size and place in these two variables.

matrixsize AS FLOAT

matrixsize = gridsize * gridmultiplier

matrixmiddle AS FLOAT

matrixmiddle = matrixsize / 2.0

rem Declare and set the matrix here.

MObj = 1 : make matrix MObj, matrixsize, matrixsize, gridsize, gridsize

prepare matrix texture MObj, MImg, 1,1

rem Set the initial position of the camera here.

position camera 0,(sin(timer() / 100.0) * 100.0) + matrixsize,300.0,(cos(timer() / 110.0) * 100.0) + matrixsize

rem Define a light to follow the camera.

CLight = 1 : make light CLight

set point light CLight, 0, 0, 0

color light CLight, 0, 255, 0

set light range CLight, 1500

rem Define two lights to roam around.

RLighta = 2 : make light RLighta

set point light RLighta, 0, 0, 0

color light RLighta, 255, 0, 0

set light range RLighta, 1500

RLightb = 3 : make light RLightb

set point light RLightb, 0, 0, 0

color light RLightb, 0, 0, 255

set light range RLightb, 1500

rem Hide the default light.

hide light 0

rem Main loop.

rem Get the new mouse position.

mouseposx = mouseposx + (mousemovex() / 5)

mouseposz = mouseposz + -(mousemovey() / 5)

rem Limit the mouse position to valid array indices.

if mouseposx > gridsize then mouseposx = gridsize

if mouseposz > gridsize then mouseposz = gridsize

if mouseposx < 1 then mouseposx = 1

if mouseposz < 1 then mouseposz = 1

rem Move the camera around slowly.

position camera 0,matrixmiddle - (sin(timer() / 100.0) * 200.0),300.0,(cos(timer() / 110.0) * 100.0)

point camera matrixmiddle,-300,matrixmiddle

rem Reposition any moving lights here.

position light CLight, camera position x(), camera position y(), camera position z()

position light RLighta, matrixmiddle - (cos(timer() / 40.0) * 200.0),100.0, matrixmiddle + (sin(timer() / 110.0) * 100.0)

position light RLightb, matrixmiddle - (sin(timer() / 100.0) * 200.0),100.0, matrixmiddle + (cos(timer() / 40.0) * 100.0)

rem Calculate current wave generator values.

sinfreq = timer() / wavefreq

sincalc = sin(sinfreq) * waveheight

coscalc = cos(sinfreq) * waveheight

rem Capture mouse values and change pattern and waveheight values accordingly.

lastclik = clik

clik = mouseclick()

if clik <> lastclik

select clik

case 0

waveheight = lowheight

endcase

case 1

waveheight = highheight

endcase

case 2

waveheight = lowheight

inc pattern

endcase

case 3

waveheight = highheight

inc pattern

endcase

endselect

endif

if pattern > 2 then pattern = 0

select pattern

case 0

print "Interference type: mouse + sine"

imgbuffer1(mouseposx, mouseposz) = imgbuffer1(mouseposx, mouseposz) + sincalc

endcase

case 1

print "Inteference type: rain"

randomize timer()

tx = rnd(gridsize - 1) + 1

ty = rnd(gridsize - 1) + 1

imgbuffer1(tx, ty) = imgbuffer1(tx, ty) - waveheight

endcase

case 2

print "Interference type: none"

endcase

endselect

rem Get the spacebar state.

lastspace = space

space = spacekey()

rem Ignore if state is same as last state.

if space <> lastspace

if space = 1

inc mtype

if mtype > 1 then mtype = 0

endif

select mtype

case 0

print "Matrix behaviour: water"

endcase

case 1

print "Matrix behaviour: memory foam"

endcase

endselect

remstart

This is the place where algorithms are calculated and applied.

The first set of embedded loops are for water, the second for a low rebound

foam-like behaviour. The third set of loops is used by both behaviours to

swap the contents of the two buffers and calculate a simple tile normal

detection algorithm.

Accuracy of the normals map is traded for execution speed in this

script. With a few extra lines of code, an averaged normals map can be

created, however this strains an Athlon XP 2000 when rendering a map with a

grid size of 128.

Remarks left out for speed.

remend

select mtype

case 0

for z = 1 to gridsize

for x = 1 to gridsize

imgbuffer2(x, z) = (imgbuffer1(x - 1, z) + imgbuffer1(x + 1, z) + imgbuffer1(x, z + 1) + imgbuffer1(x, z - 1)) / 2 - imgbuffer2(x, z)

imgbuffer2(x, z) = imgbuffer2(x, z) * damping

next x

next z

endcase

case 1

for z = 1 to gridsize

for x = 1 to gridsize

imgbuffer2(x, z) = imgbuffer1(x, z) * damping

next x

next z

endcase

endselect

for z = 1 to gridsize

for x = 1 to gridsize

tmp = imgbuffer1(x, z)

imgbuffer1(x, z) = imgbuffer2(x, z)

imgbuffer2(x, z) = tmp

set matrix height MObj, x, z, imgbuffer2(x, z)

set vector3 1,0.0,imgbuffer2(x, z),0.0

set vector3 2,-1.0,imgbuffer2(x - 1, z),0.0

set vector3 3,0.0,imgbuffer2(x, z + 1),1.0

subtract vector3 4, 1, 2

subtract vector3 5, 2, 3

cross product vector3 6, 4, 5

normalize vector3 6, 6

set matrix normal MObj, x, z, x vector3(6), y vector3(6), z vector3(6)

next x

next z

rem done with algorithms. Update matrix with new values.

update matrix MObj

rem print out a status display.

sfps = screen fps()

rem mouse pointer values and frames per second.

set cursor 0,1 : print "mpx: "; mouseposx; " mpz: "; mouseposz; " fps: "; sfps

rem quick polygons per second calculation.

pps = statistic(1) * sfps

print pps;" polygons per second."

rem flip the buffers.

sync

rem end of main loop.

loop

rem That's it, folks!

end

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Author Name:	Tinkerer
CodeBase Entries:	2

CodeBase - Ye olde water algorithm Mk. 2

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DarkBASIC Professional Source Code

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