! Copyright (C) 2009 Joe Groff, Doug Coleman.
! See https://factorcode.org/license.txt for BSD license.
USING: accessors arrays combinators combinators.short-circuit
destructors game.input game.input.scancodes game.loop
game.worlds grid-meshes grouping kernel literals math
math.functions math.matrices.simd math.order
math.vectors math.vectors.simd noise opengl
opengl.capabilities opengl.gl opengl.shaders opengl.textures
sequences specialized-arrays terrain.generation terrain.shaders
typed ui ui.gadgets.worlds ui.gestures ui.pixel-formats ;
QUALIFIED-WITH: alien.c-types c
SPECIALIZED-ARRAY: c:float
IN: terrain

CONSTANT: FOV $[ 2.0 sqrt 1 + ]
CONSTANT: NEAR-PLANE 1/1024.
CONSTANT: FAR-PLANE 2.0
CONSTANT: PLAYER-START-LOCATION float-4{ 0.5 0.51 0.5 1.0 }
CONSTANT: VELOCITY-MODIFIER-NORMAL float-4{ 1.0 1.0 1.0 0.0 }
CONSTANT: VELOCITY-MODIFIER-FAST float-4{ 2.0 1.0 2.0 0.0 }
CONSTANT: BOUNCE float-4{ 1.0 -0.2 1.0 1.0 }
CONSTANT: PLAYER-HEIGHT 1/256.
CONSTANT: GRAVITY float-4{ 0.0 -1/8192. 0.0 0.0 }
CONSTANT: JUMP 1/2048.
CONSTANT: MOUSE-SCALE 1/20.
CONSTANT: MOVEMENT-SPEED 1/32768.
CONSTANT: FRICTION float-4{ 0.97 0.995 0.97 1.0 }
CONSTANT: COMPONENT-SCALE float-4{ 0.5 0.01 0.0005 0.0 }
CONSTANT: SKY-PERIOD 2400
CONSTANT: SKY-SPEED 0.00025

CONSTANT: terrain-vertex-size { 512 512 }

TUPLE: player
    { location float-4 }
    { yaw float }
    { pitch float }
    { velocity float-4 }
    { velocity-modifier float-4 }
    reverse-time ;

TUPLE: terrain-world < game-world
    { player player }
    sky-image sky-texture sky-program
    terrain terrain-segment terrain-texture terrain-program
    terrain-mesh
    history ;

: <player> ( -- player )
    player new
        PLAYER-START-LOCATION >>location
        0.0 >>yaw
        0.0 >>pitch
        float-4{ 0.0 0.0 0.0 1.0 } >>velocity
        VELOCITY-MODIFIER-NORMAL >>velocity-modifier ;

: frustum ( dim -- -x x -y y near far )
    dup first2 min v/n
    NEAR-PLANE FOV / v*n first2 [ [ neg ] keep ] bi@
    NEAR-PLANE FAR-PLANE ;

: set-modelview-matrix ( gadget -- )
    GL_DEPTH_BUFFER_BIT glClear
    GL_MODELVIEW glMatrixMode
    glLoadIdentity
    player>>
    [ pitch>> 1.0 0.0 0.0 glRotatef ]
    [ yaw>> 0.0 1.0 0.0 glRotatef ]
    [ location>> vneg first3 glTranslatef ] tri ;

TYPED: eye-rotate ( yaw: float pitch: float v: float-4 -- v': float-4 )
    [ float-4{  0.0 -1.0 0.0 0.0 } swap deg>rad rotation-matrix4 ]
    [ float-4{ -1.0  0.0 0.0 0.0 } swap deg>rad rotation-matrix4 m4. ]
    [ m4.v ] tri* float-4{ t t t f } vand ;

: forward-vector ( player -- v )
    yaw>> 0.0
    float-4{ 0.0 0.0 $ MOVEMENT-SPEED 1.0 } vneg eye-rotate ; inline
: rightward-vector ( player -- v )
    yaw>> 0.0
    float-4{ $ MOVEMENT-SPEED 0.0 0.0 1.0 } eye-rotate ; inline
: clamp-pitch ( pitch -- pitch' )
    -90.0 90.0 clamp ; inline

: walk-forward ( player -- )
    dup forward-vector [ v+ ] curry change-velocity drop ; inline
: walk-backward ( player -- )
    dup forward-vector [ v- ] curry change-velocity drop ; inline
: walk-leftward ( player -- )
    dup rightward-vector [ v- ] curry change-velocity drop ; inline
: walk-rightward ( player -- )
    dup rightward-vector [ v+ ] curry change-velocity drop ; inline
: jump ( player -- )
    [ float-4{ 0.0 $ JUMP 0.0 0.0 } v+ ] change-velocity drop ; inline
: rotate-leftward ( player x -- )
    [ - ] curry change-yaw drop ; inline
: rotate-rightward ( player x -- )
    [ + ] curry change-yaw drop ; inline
: look-horizontally ( player x -- )
    [ + ] curry change-yaw drop ; inline
: look-vertically ( player x -- )
    [ + clamp-pitch ] curry change-pitch drop ; inline


: rotate-with-mouse ( player mouse -- )
    [ dx>> MOUSE-SCALE * look-horizontally ]
    [ dy>> MOUSE-SCALE * look-vertically ] 2bi ;


terrain-world H{
    { T{ key-down { mods { A+ } } { sym "RET" } } [ toggle-fullscreen ] }
} set-gestures

:: handle-input ( world -- )
    world player>> :> player
    read-keyboard keys>> :> keys

    key-left-shift keys nth
    VELOCITY-MODIFIER-FAST VELOCITY-MODIFIER-NORMAL ? player velocity-modifier<<

    {
        [ key-1 keys nth 1  f ? ]
        [ key-2 keys nth 2  f ? ]
        [ key-3 keys nth 3  f ? ]
        [ key-4 keys nth 4  f ? ]
        [ key-5 keys nth 10000 f ? ]
    } 0|| player reverse-time<<

    key-w keys nth [ player walk-forward ] when
    key-s keys nth [ player walk-backward ] when
    key-a keys nth [ player walk-leftward ] when
    key-d keys nth [ player walk-rightward ] when
    key-q keys nth [ player -1 look-horizontally ] when
    key-e keys nth [ player 1 look-horizontally ] when
    key-left-arrow keys nth [ player -1 look-horizontally ] when
    key-right-arrow keys nth [ player 1 look-horizontally ] when
    key-down-arrow keys nth [ player 1 look-vertically ] when
    key-up-arrow keys nth [ player -1 look-vertically ] when
    key-space keys nth [ player jump ] when
    key-escape keys nth [ world close-window ] when
    player read-mouse rotate-with-mouse
    reset-mouse ;

: apply-friction ( velocity -- velocity' )
    FRICTION v* ;

: apply-gravity ( velocity -- velocity' )
    GRAVITY v+ ;

: clamp-coords ( coords dim -- coords' )
    { 0 0 } swap { 2 2 } v- vclamp ;

:: pixel-indices ( coords dim -- indices )
    coords vfloor v>integer dim clamp-coords :> floor-coords
    floor-coords first2 dim first * + :> base-index
    base-index dim first + :> next-row-index

    base-index
    base-index 1 +
    next-row-index
    next-row-index 1 + 4array ;

:: terrain-height-at ( segment point -- height )
    segment dim>> :> dim
    dim point v* :> pixel
    pixel dup vfloor v- :> pixel-mantissa
    segment bitmap>> 4 <groups> :> pixels
    pixel dim pixel-indices :> indices

    indices [ pixels nth COMPONENT-SCALE vdot 255.0 / ] map
    first4 pixel-mantissa bilerp ;

: (collide) ( segment location -- location' )
    [
        { 0 2 3 3 } vshuffle terrain-height-at PLAYER-HEIGHT +
        -1/0. swap -1/0. -1/0. float-4-boa
    ] keep vmax ; inline

TYPED:: collide ( world: terrain-world player: player -- )
    world terrain-segment>> :> segment
    player location>> :> location
    segment location (collide) :> location'

    location location' = not [
        player
            location' >>location
            [ BOUNCE v* ] change-velocity
            drop
    ] when ;

: scaled-velocity ( player -- velocity )
    [ velocity>> ] [ velocity-modifier>> ] bi v* ;

: save-history ( world player -- )
    clone swap history>> push ;

:: tick-player-reverse ( world player -- )
    player reverse-time>> :> reverse-time
    world history>> :> history
    history length 0 > [
        history length reverse-time 1 - - 1 max history set-length
        history pop world player<<
    ] when ;

: tick-player-forward ( world player -- )
    2dup save-history
    [ apply-friction apply-gravity ] change-velocity
    dup scaled-velocity [ v+ ] curry change-location
    collide ;

: tick-player ( world player -- )
    dup reverse-time>>
    [ tick-player-reverse ]
    [ tick-player-forward ] if ;

M: terrain-world tick-game-world
    [ dup focused?>> [ handle-input ] [ drop ] if ]
    [ dup player>> tick-player ] bi ;

: set-texture-parameters ( texture -- )
    GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit
    GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER GL_LINEAR glTexParameteri
    GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER GL_LINEAR glTexParameteri
    GL_TEXTURE_2D GL_TEXTURE_WRAP_S GL_CLAMP_TO_EDGE glTexParameteri
    GL_TEXTURE_2D GL_TEXTURE_WRAP_T GL_CLAMP_TO_EDGE glTexParameteri ;

: sky-gradient ( world -- t )
    game-loop>> tick#>> SKY-PERIOD mod SKY-PERIOD /f ;
: sky-theta ( world -- theta )
    game-loop>> tick#>> SKY-SPEED * ;

M: terrain-world begin-game-world
    "2.0" { "GL_ARB_vertex_buffer_object" "GL_ARB_shader_objects" }
    require-gl-version-or-extensions
    GL_DEPTH_TEST glEnable
    GL_TEXTURE_2D glEnable
    GL_VERTEX_ARRAY glEnableClientState
    <player> >>player
    V{ } clone >>history
    <perlin-noise-table> 0.01 float-4-with scale-matrix4 { 512 512 } perlin-noise-image
    [ >>sky-image ] keep
    make-texture [ set-texture-parameters ] keep >>sky-texture
    <terrain> [ >>terrain ] keep
    float-4{ 0.0 0.0 0.0 1.0 } terrain-segment [ >>terrain-segment ] keep
    make-texture [ set-texture-parameters ] keep >>terrain-texture
    sky-vertex-shader sky-pixel-shader <simple-gl-program>
    >>sky-program
    terrain-vertex-shader terrain-pixel-shader <simple-gl-program>
    >>terrain-program
    terrain-vertex-size <grid-mesh> >>terrain-mesh
    drop ;

M: terrain-world end-game-world
    {
        [ terrain-mesh>> dispose ]
        [ terrain-program>> delete-gl-program ]
        [ terrain-texture>> delete-texture ]
        [ sky-program>> delete-gl-program ]
        [ sky-texture>> delete-texture ]
    } cleave ;

M: terrain-world resize-world
    GL_PROJECTION glMatrixMode
    glLoadIdentity
    dim>> [ [ { 0 0 } ] dip gl-viewport ]
    [ frustum glFrustum ] bi ;

M: terrain-world draw-world*
    {
        [ set-modelview-matrix ]
        [ terrain-texture>> GL_TEXTURE_2D GL_TEXTURE0 bind-texture-unit ]
        [ sky-texture>> GL_TEXTURE_2D GL_TEXTURE1 bind-texture-unit ]
        [ GL_DEPTH_TEST glDisable dup sky-program>> [
            [ nip "sky" glGetUniformLocation 1 glUniform1i ]
            [ "sky_gradient" glGetUniformLocation swap sky-gradient glUniform1f ]
            [ "sky_theta" glGetUniformLocation swap sky-theta glUniform1f ] 2tri
            { -1.0 -1.0 } { 2.0 2.0 } gl-fill-rect
        ] with-gl-program ]
        [ GL_DEPTH_TEST glEnable dup terrain-program>> [
            [ "heightmap" glGetUniformLocation 0 glUniform1i ]
            [ "component_scale" glGetUniformLocation COMPONENT-SCALE first4 glUniform4f ] bi
            terrain-mesh>> draw-grid-mesh
        ] with-gl-program ]
    } cleave gl-error ;

GAME: terrain-game {
        { world-class terrain-world }
        { title "Terrain" }
        { pixel-format-attributes {
            windowed
            double-buffered
            T{ depth-bits { value 24 } }
        } }
        { use-game-input? t }
        { grab-input? t }
        { pref-dim { 1024 768 } }
        { tick-interval-nanos $[ 60 fps ] }
    } ;