'///////////////////////////////////////////////////////////////////////////////////////////////////////////////

'// Unseen GDK_GL - Single Particle Jet \\

'///////////////////////////////////////////////////////////////////////////////////////////////////////////////



REM $INCLUDE:'UnseenGDK_DEV\GDK2_GL.bi'



Debug%% = GDK_TRUE



CONST nP = 50000



'//////////////////////// UDTs ///////////////////////////////////////



TYPE FTN_Particle

  Position AS GDK2_Vertex_F

  Velocity AS GDK2_Vertex_F

  Color AS _UNSIGNED LONG

  Alpha AS _BYTE

  BounceCount AS INTEGER

  Lifetime AS SINGLE

END TYPE



TYPE FTN_Fountain

  Origin AS GDK2_Vertex_F

  NumParticles AS LONG

END TYPE





'//////////////////////// Global Variables /////////////////////////////

DIM SHARED Fountain AS FTN_Fountain

DIM SHARED Particles(1 TO nP) AS FTN_Particle ' The shared particle array

DIM SHARED MaxBounce AS INTEGER: MaxBounce = 3

DIM SHARED ParticleMaxLifetime AS SINGLE: ParticleMaxLifetime = 350



'///////////////////////////////////// System Initialisation ////////////////////////////////////////////////

GDK2_System_New "UnseenGDK_Dev\", 800, 600, GDK_FALSE, ""

_DISPLAYORDER _GLRENDER , _SOFTWARE

_MOUSEHIDE

GDK_Init_GL = GDK_TRUE

GDK_Allow_GL = GDK_TRUE



Initialize_Fountain Fountain, Particles(), nP



'//////////////////////////////////////// Main Loop ////////////////////////////////////////////////////////////

DO

  GDK2_System_Update

  Update_Fountain_Physics Fountain, Particles()

LOOP UNTIL GDK_KB(0).ESC

SYSTEM



'///////////////////////////////////////////////////////////////////////////////////////////////////////////////

REM $INCLUDE:'UnseenGDK_DEV\GDK2_GL.bm'

'///////////////////////////////////////////////////////////////////////////////////////////////////////////////



SUB _GL

  IF GDK_Allow_GL = GDK_TRUE THEN

    _GLCLEARDEPTH 1

    _GLCLEARCOLOR 0, 0, 0, 1

    _GLENABLE _GL_DEPTH_TEST

    _GLENABLE _GL_BLEND

    _GLBLENDFUNC _GL_SRC_ALPHA, _GL_ONE_MINUS_SRC_ALPHA

    _GLENABLE _GL_TEXTURE_2D

    _GLMATRIXMODE _GL_PROJECTION

    _GLLOADIDENTITY

    _GLUPERSPECTIVE 65, GDK_System.WH.X / GDK_System.WH.Y, 1, 1000

    _GLMATRIXMODE _GL_MODELVIEW

    _GLLOADIDENTITY

    _GLVIEWPORT 0, 0, GDK_System.WH.X, GDK_System.WH.Y



    IF GDK_Init_GL = GDK_TRUE THEN

      GDK_Init_GL = GDK_FALSE

    ELSE

      GDK_GL_CLS

      _GLTRANSLATEF 0, 0, -500

      Draw_Particles Fountain, Particles()

      _DISPLAY

    END IF

  END IF

END SUB



SUB Initialize_Fountain (fountain AS FTN_Fountain, particles() AS FTN_Particle, maxParticles AS LONG)

  DIM i AS LONG

  fountain.NumParticles = 0

  fountain.Origin.X = GDK_System.WH.X / 2

  fountain.Origin.Y = GDK_System.WH.Y

  fountain.Origin.Z = 0

  FOR i = 1 TO maxParticles

    Reset_Particle particles(i), fountain

  NEXT i

END SUB



SUB Reset_Particle (particle AS FTN_Particle, fountain AS FTN_Fountain)

  DIM dynamicHeight AS SINGLE

  DIM minHeight AS SINGLE, maxHeight AS SINGLE

  DIM freq AS SINGLE



  minHeight = 15

  maxHeight = 40

  freq = 0.5 ' Frequency of the height change



  ' Calculate the current dynamic height using a sine wave and GDK_System.GT

  dynamicHeight = (SIN(GDK_System.GT * freq) * ((maxHeight - minHeight) / 2)) + (minHeight + (maxHeight - minHeight) / 2)



  particle.BounceCount = 0

  particle.Position.X = fountain.Origin.X + RND * 20 - 10

  particle.Position.Y = fountain.Origin.Y

  particle.Position.Z = fountain.Origin.Z + RND * 10 - 5

  particle.Lifetime = ParticleMaxLifetime * (RND * .5 + .75)



  ' Apply the dynamically changing velocity

  particle.Velocity.X = RND * 1 - .5

  particle.Velocity.Y = dynamicHeight + (RND * 2) - 2.5

  particle.Velocity.Z = RND * 1 - .5



  particle.Color = _RGBA32(5 * RND + 15, 50 * RND + 16, 255, 64)

  particle.Alpha = _ALPHA32(particle.Color)

END SUB



SUB Update_Fountain_Physics (fountain AS FTN_Fountain, particles() AS FTN_Particle)

  DIM i AS LONG



  IF fountain.NumParticles < nP THEN fountain.NumParticles = fountain.NumParticles + 100



  FOR i = 1 TO fountain.NumParticles

    DIM particle AS FTN_Particle: particle = particles(i)



    ' Gravity

    particle.Velocity.Y = particle.Velocity.Y + .1



    ' Update position

    particle.Position.X = particle.Position.X + particle.Velocity.X

    particle.Position.Y = particle.Position.Y + particle.Velocity.Y

    particle.Position.Z = particle.Position.Z + particle.Velocity.Z



    ' Update particle lifetime and alpha

    particle.Lifetime = particle.Lifetime - 1

    IF particle.Lifetime < 0 THEN particle.Lifetime = 0

    particle.Alpha = 64 * (particle.Lifetime / (ParticleMaxLifetime * 1.25))



    ' Check for reset conditions

    IF (particle.Position.Y > GDK_System.WH.Y + 20 AND particle.Velocity.Y > 0 AND particle.BounceCount >= MaxBounce) OR particle.Lifetime <= 0 THEN

      Reset_Particle particle, fountain

    END IF



    ' Boundary check for bouncing

    IF particle.Position.Y > GDK_System.WH.Y + 20 AND particle.Velocity.Y > 0 AND particle.BounceCount < MaxBounce THEN

      particle.Velocity.Y = -particle.Velocity.Y * (RND * .2 + .5)

      particle.Position.Y = GDK_System.WH.Y + 19

      particle.Velocity.X = (RND - .5) * 2

      particle.Velocity.Z = (RND - .5) * 2

      particle.BounceCount = particle.BounceCount + 1

    END IF



    particles(i) = particle

  NEXT i

END SUB



SUB Draw_Particles (fountain AS FTN_Fountain, particles() AS FTN_Particle)

  DIM i AS LONG

  _GLPOINTSIZE 2.0

  _GLBEGIN _GL_POINTS

  FOR i = 1 TO fountain.NumParticles

    _GLCOLOR4UB _RED32(particles(i).Color), _GREEN32(particles(i).Color), _BLUE32(particles(i).Color), particles(i).Alpha

    _GLVERTEX3F particles(i).Position.X - (GDK_System.WH.X / 2), GDK_System.WH.Y - particles(i).Position.Y - (GDK_System.WH.Y / 2), particles(i).Position.Z

  NEXT i

  _GLEND

END SUB