eruta/engine/tile/pane.go

package tile

import "fmt"

import "gitlab.com/beoran/al5go/al"
// import "gitlab.com/beoran/ebsgo/engine/geometry/point"
import "gitlab.com/beoran/ebsgo/engine/physics"
import "gitlab.com/beoran/ebsgo/engine/fifi"



/* Tile blending direction constants. */

const (
    BLEND_NORTHWEST            = 0 
    BLEND_NORTH                = 1
    BLEND_NORTHEAST            = 2
    BLEND_WEST                 = 3
    BLEND_EAST                 = 4
    BLEND_SOUTHWEST            = 5
    BLEND_SOUTH                = 6
    BLEND_SOUTHEAST            = 7
    BLEND_DIRECTION_MAX        = 8
)

/* Tile blending shapes */
const (
    BLEND_CORNER               = 0
    BLEND_SIDE                 = 1
    BLEND_SHAPE_MAX            = 2
)

/* Tile blending types. */
const (
    BLEND_SHARP                = 0
    BLEND_GRADUAL              = 1
    BLEND_FUZZY                = 2
    BLEND_FUZZY_GRADUAL        = 3
    BLEND_TYPE_MAX             = 4
)

const BLEND_BITMAPS_MAX = 255 

/* A cache of generated generic blending masks. */
var BlendMasks [BLEND_TYPE_MAX][BLEND_SHAPE_MAX]*al.Bitmap 


/* Lookup array with info on how the mask should be applied, i. e. flipped. */
var BlendFlags [BLEND_DIRECTION_MAX]int = [BLEND_DIRECTION_MAX] int{
  0,
  0,
  al.FLIP_HORIZONTAL,
  0,
  al.FLIP_HORIZONTAL,
  al.FLIP_VERTICAL,
  al.FLIP_VERTICAL,
  al.FLIP_HORIZONTAL | al.FLIP_VERTICAL,
}

/* Lookup array with info on which "side" mask should be used. */
var BlendSides [BLEND_DIRECTION_MAX]int = [BLEND_DIRECTION_MAX]int {
  BLEND_CORNER,
  BLEND_SIDE  ,
  BLEND_CORNER,
  BLEND_SIDE  ,
  BLEND_SIDE  ,
  BLEND_CORNER,
  BLEND_SIDE  ,
  BLEND_CORNER,
}

/* Lookup array with info on how the mask should be turned, i. e. rotated. */
var BlendAngles [BLEND_DIRECTION_MAX]float32 = [BLEND_DIRECTION_MAX]float32 {
  0.0,
  0.0,
  0.0,
  3 * al.PI / 2.0,
  al.PI / 2.0,
  0.0,
  0.0,
  0.0,
}

/* 
 
 ## Implementation of automatic overlapping ##
 
 In the simple case where there are only 2 different kinds of tiles, 
 then for a tile somewhere in the map, that tile has 8 neighbours, and thus 
 there are 8**2 or 256 different possible layouts of these neighbours around that 
 single tile, and 256 different blends would be needed.
 
 Of course, this is a staggering amount for hand drawn graphics, and even for 
 automatically generated mask images, this takes up a hefty chunk of memory,
 so some kind of simplification is needed. 
 
 The first simplification is the use of the tile's blend value as a blend *priority*
 value. The tile with the lower blend priority will be blended with the 
 tile with the higher blend priority blending over it. Tiles with equal blend 
 priority will simply not blend. This reduces the possibilities because in 
 cases where 3 or more tyle types must blend, without priorities, 
 the number of possible blends would become even larger. 
 
 Let's consider the possibilities takng symmetry in account. If only 2 tiles 
 that will blend are adjacent, there are 8 possibilities. However there are 4 
 symmetric rotations of the 2 cases of the 2 tiles being either side-to-side 
 or corner to corner. In case of side-to side, the blend should go rougmly like 
 this: (scaled down to 8x8
 
 ..........OOOOOOOO     ................OO
 ..........OOOOOOOO     ..............OOOO
 ..........OOOOOOOO     ............OOOOOO
 ..........OOOOOOOO     ............OOOOOO
 ..........OOOOOOOO =>  ............OOOOOO
 ..........OOOOOOOO     ............OOOOOO
 ..........OOOOOOOO     ...........OOOOOOO
 ..........OOOOOOOO     ..........OOOOOOOO
 
 And corner to corner:
 
           OOOOOOOO               OOOOOOOO
           OOOOOOOO               OOOOOOOO
           OOOOOOOO               OOOOOOOO
           OOOOOOOO               OOOOOOOO
           OOOOOOOO =>            OOOOOOOO
           OOOOOOOO               OOOOOOOO
           OOOOOOOO               .OOOOOOO
           OOOOOOOO               ..OOOOOO
 ..........             ..........        
 ..........             ..........        
 ..........             ..........        
 ..........             ..........        
 ..........         =>  ..........        
 ..........             ..........        
 ..........             ..........        
 ..........             ..........        
 
 If the masks are judiciouly chosen, and all align correctly, 
 then it will suffice to have just 2 mask images which get rotated as needed,
 one mask for the side to side, and one for corner to corner. 
 Each of the masks follows a strict pattern, that is, the side by side 
 has a \__/ - like shape were the depth of the overlap is at most 1/4th of the 
 tile height. (Or is it 1/3, let's check it out). 
 
 Then, for every overlapping tile, an overlap bitmap can be generated 
 when loading the tile layer it is in, and that bitmap can then be used to 
 draw the tile in stead of the original bitmap. 


## Implementation of automatic shadows ##

Every cell in the tile pane contains a slice of shadow polygons,
that is set up before rendering. This should in the future be used in stead of 
the current live polygons generated at draw time but this will require 
an approach where a camera transform is applied whilst drawing in stead of
the current situation where we use the camera info directly to calculate
the draw positions. 

*/

func PrepareBlend(blend * al.Bitmap, tile * Tile, blentile * Tile, direction int ) * al.Bitmap {
    side  := BlendSides[direction]
    angle := BlendAngles[direction]
    flags := BlendFlags[direction]
    maskid:= tile.BlendMask
    mask  := BlendMasks[maskid][side]
    if mask == nil {
        return nil
    } else {
        tile.DrawMaskedTo(blend, mask, angle, flags)
        return blend
    }
}

/** 
 * A Cell is an individual part of a pane. It contains a tile,
 * a blend bitmap, two shadow polygons, and rendering flags.
 */
type Cell struct {
    * Tile
    Blend * al.Bitmap
    Flags   int
    Rotate  float32
    Shadows [][8]float32 // Slice of shadow polygons.
}


/**
* A Pane is a layer of tiles for use in a tile map or tiled
* background. A pane consists of individual tiles from the same
* tile set. Different panes may have different tile sets.
*/
type Pane struct  {
  Tileset   *    Set
  Cells      [][]Cell
  GridW          int
  GridH          int
  PixelW         int
  PixelH         int
  // This bitmap is the atlas used for blends. XXX: Not implemented yet.
  Blends         * al.Bitmap
  Name           string
};

/* First group id of the tile set of the plane. */
func (pane * Pane) FirstGID() int {
    if pane.Tileset == nil {
        return 0
    } else {
        return pane.Tileset.FirstGID
    }
}


/** Initializes a tile pane.
* The pane will not clean up the tile set itself!
*/
func (pane * Pane) Init(set * Set, gridw, gridh int, name string) (* Pane) {
    pane.Tileset = set
    pane.GridW   = gridw
    pane.GridH   = gridh
    pane.PixelW  = pane.GridW * set.TileW
    pane.PixelH  = pane.GridW * set.TileH
    pane.Name    = name
    pane.Cells   = make([][]Cell, pane.GridH)
    for i := range (pane.Cells) {
        pane.Cells[i]  = make([]Cell, pane.GridW)
    }
    return pane
}

func NewPane(set * Set, gridw, gridh int, name string) (pane * Pane) {
    pane = &Pane{}
    return pane.Init(set, gridw, gridh, name)
}
 

func (pane * Pane) Outside(gridx, gridy int) bool {
    return ((gridx < 0) || (gridy < 0)) || 
    ((gridx >= pane.GridW) || (gridy >= pane.GridH))
}

func (pane * Pane) Cell(gridx, gridy int) * Cell {
    if pane.Outside(gridx, gridy) {
        return nil
    }
    return & pane.Cells[gridy][gridx]
}

func (pane * Pane) Tile(gridx, gridy int) * Tile {
    if pane.Outside(gridx, gridy) {
        return nil
    }
    return pane.Cells[gridy][gridx].Tile
}

func (pane * Pane) Blend(gridx, gridy int) * al.Bitmap {
    if pane.Outside(gridx, gridy) {
        return nil
    }
    return pane.Cells[gridy][gridx].Blend
}


func (pane * Pane) SetTile(gridx, gridy int, tile * Tile) * Tile {
    if pane.Outside(gridx, gridy) {
        return nil
    }
    pane.Cells[gridy][gridx].Tile = tile
    return tile
}

func (pane * Pane) SetTileIndex(gridx, gridy, index int) * Tile {
    return pane.SetTile(gridx, gridy, pane.Tileset.Tile(index))
}


func (pane * Pane) SetBlend(gridx, gridy int, blend * al.Bitmap) * al.Bitmap {
    if pane.Outside(gridx, gridy) {
        return nil
    }
    if nil != pane.Cells[gridy][gridx].Blend {
        pane.Cells[gridy][gridx].Blend.Destroy()
    }
    pane.Cells[gridy][gridx].Blend = blend
    return blend
}


func (pane * Pane) SetFlags(gridx, gridy int, flags int) int {
    if pane.Outside(gridx, gridy) {
        return -1
    }
    pane.Cells[gridy][gridx].Flags = flags
    return flags
}


func (pane * Pane) SetTileRect(gridx, gridy, gridw, gridh int, tile * Tile) * Tile {
    for jj := gridy ; jj < (gridy + gridh) ; jj++ {
        for ii := gridx ; ii < (gridx + gridh) ; ii++ {
            pane.SetTile(ii, jj, tile)
        }
    }
    return tile
}

func (pane * Pane) Fill(tile * Tile) * Tile {
    return pane.SetTileRect(0, 0, pane.GridW, pane.GridH, nil)
}


func (cell * Cell) AddShadowPolygon(polygon [8]float32) {
    cell.Shadows = append(cell.Shadows, polygon)
}

func (cell * Cell) DeleteShadowPolygons() {
    cell.Shadows = nil
}

type DrawIterator func (cell * Cell, x, y float32, tx, ty int)  

/* Draws the tiles of the pane using an iterator function. 
 * This must be done in one call because changing the source bitmap is less optimal. 
 * You must hold bitmap drawing yourself if applicable.
 */
func (pane * Pane) DrawIterate(camera * physics.Camera, iter DrawIterator) { 
    gridwide := pane.GridW
    gridhigh := pane.GridH
    tilewide := pane.Tileset.TileW
    tilehigh := pane.Tileset.TileH
    x        := int(camera.X)
    y        := int(camera.Y)
    tx_start := x / tilewide
    ty_start := y / tilehigh
    tx_delta := 1 + (int(camera.W) / tilewide)
    ty_delta := 1 + (int(camera.H) / tilehigh)
    tx_stop  := tx_start + tx_delta
    ty_stop  := ty_start + ty_delta
    tx_index := 0
    ty_index := 0
    // realwide := pane.PixelW
    // realhigh := pane.PixelH
    // drawflag := 0
    if tx_start < 0 { tx_start = 0; }
    if ty_start < 0 { ty_start = 0; }
    if tx_stop  > gridwide { tx_stop = gridwide; }
    if ty_stop  > gridhigh { ty_stop = gridhigh; }
    y_draw    :=  float32(-y + (ty_start * tilehigh))
    for ty_index = ty_start; ty_index < ty_stop; ty_index++ { 
        y_draw   += float32(tilehigh)
        x_draw   := float32(-x + (tx_start * tilewide))
        row      := pane.Cells[ty_index]
        for tx_index = tx_start ; tx_index < tx_stop; tx_index++ {
            x_draw += float32(tilewide)
            cell := &row[tx_index]
            iter(cell, x_draw, y_draw, tx_index, ty_index)
        }
    }
}



/* Draws the tiles of the pane. This must be done in one call because
 * changing the source bitmap is less optimal. */
func (pane * Pane) DrawTiles(camera * physics.Camera) { 
    gridwide := pane.GridW
    gridhigh := pane.GridH
    tilewide := pane.Tileset.TileW
    tilehigh := pane.Tileset.TileH
    x        := int(camera.X)
    y        := int(camera.Y)
    tx_start := x / tilewide
    ty_start := y / tilehigh
    tx_delta := 1 + (int(camera.W) / tilewide)
    ty_delta := 1 + (int(camera.H) / tilehigh)
    tx_stop  := tx_start + tx_delta
    ty_stop  := ty_start + ty_delta
    tx_index := 0
    ty_index := 0
    // realwide := pane.PixelW
    // realhigh := pane.PixelH
    // drawflag := 0
    al.HoldBitmapDrawing(true)
    if tx_start < 0 { tx_start = 0; }
    if ty_start < 0 { ty_start = 0; }
    if tx_stop  > gridwide { tx_stop = gridwide; }
    if ty_stop  > gridhigh { ty_stop = gridhigh; }
    y_draw    :=  float32(-y + (ty_start * tilehigh))
    for ty_index = ty_start; ty_index < ty_stop; ty_index++ { 
        y_draw   += float32(tilehigh)
        x_draw   := float32(-x + (tx_start * tilewide))
        row      := pane.Cells[ty_index]
        for tx_index = tx_start ; tx_index < tx_stop; tx_index++ {
            x_draw += float32(tilewide)
            cell := row[tx_index]
            if (cell.Tile != nil) {
                cell.Tile.Draw(x_draw, y_draw, cell.Flags)
            }
        }
    }
    // Let go of hold 
    al.HoldBitmapDrawing(false)  
}


/* Draws the blends of the pane. This must be done in one call because
 * changing the source bitmap is less optimal. */
func (pane * Pane) DrawBlends(camera * physics.Camera) { 
    gridwide := pane.GridW
    gridhigh := pane.GridH
    tilewide := pane.Tileset.TileW
    tilehigh := pane.Tileset.TileH
    x        := int(camera.X)
    y        := int(camera.Y)
    tx_start := x / tilewide
    ty_start := y / tilehigh
    tx_delta := 1 + (int(camera.W) / tilewide)
    ty_delta := 1 + (int(camera.H) / tilehigh)
    tx_stop  := tx_start + tx_delta
    ty_stop  := ty_start + ty_delta
    tx_index := 0
    ty_index := 0
    // realwide := pane.PixelW
    // realhigh := pane.PixelH
    // drawflag := 0
    // al.HoldBitmapDrawing(true)
    if tx_start < 0 { tx_start = 0; }
    if ty_start < 0 { ty_start = 0; }
    if tx_stop  > gridwide { tx_stop = gridwide; }
    if ty_stop  > gridhigh { ty_stop = gridhigh; }
    y_draw    :=  float32(-y + (ty_start * tilehigh))
    for ty_index = ty_start; ty_index < ty_stop; ty_index++ { 
        y_draw   += float32(tilehigh)
        x_draw   := float32(-x + (tx_start * tilewide))
        row      := pane.Cells[ty_index]
        for tx_index = tx_start ; tx_index < tx_stop; tx_index++ {
            x_draw += float32(tilewide)
            cell := row[tx_index]
            if (cell.Blend != nil) {
                cell.Blend.Draw(x_draw, y_draw, cell.Flags)
            }
        }
    }
    // Let go of hold 
    // al.HoldBitmapDrawing(false)  
}


func (pane * Pane) DrawOneShadowOn(cell * Cell, pane_below * Pane, 
                                   tx, ty int, x, y float32) {

    tile      :=  cell.Tile
    if (tile == nil) { return; }
    if (tile.Shadow == 0) { return; }
    shadow_color := al.MapRGBA(0, 0, 0, 128)

    edge_tile :=  pane.Tile(tx + 1, ty - 1)
    aid_tile  :=  pane.Tile(tx + 1, ty)
    shadow_trapezium := false
    if (edge_tile != nil) && edge_tile.IsWall() {
        shadow_trapezium = true
        // here the shadow is at trapezium, not a parallelogram.
    }
    
    /* Tile sizes... */
    tw := float32(pane.Tileset.TileW)
    th := float32(pane.Tileset.TileH)
    
      
    /* Only cast a shadow to the east if no solid tile next to self.
     * Shadow is a parallelogram to simplify overlaps.
     */
     if (aid_tile == nil) || !aid_tile.IsWall() { 
        low_tile  := pane_below.Tile(tx + 1, ty)
        if (low_tile != nil) && (low_tile.ShadowMask != 1) {
            polygon := [8]float32 {
                x + tw          , y             , 
                x + tw          , y + th        ,
                x + tw * 1.5    , y + th * 0.5  ,
                x + tw * 1.5    , y - th * 0.5  ,
            }
            
            if (shadow_trapezium) {
                polygon[7] = y
            }
            al.DrawFilledPolygon(polygon[0:8], 0, shadow_color)
        }
      }
      
      aid_tile = pane.Tile(tx, ty-1)

      /* Only cast a shadow to the north if no solid tile above to self.
       * Shadow is a parallelogram to simplify overlaps.
       */
       
      if (aid_tile == nil) || !aid_tile.IsWall() { 
        low_tile  := pane_below.Tile(tx, ty - 1)
        if (low_tile != nil) && (low_tile.ShadowMask != 1) {
            polygon := [8]float32 {
                x + tw          , y             , 
                x + tw          , y             ,
                x + tw * 1.5    , y - th * 0.5  ,
                x + tw * 0.5    , y - th * 0.5  ,
            }
            
            if (shadow_trapezium) {
                polygon[4] = x + tw
            }
            al.DrawFilledPolygon(polygon[0:8], 0, shadow_color)
        }
      }
}

/** Draws the shadows that tile pane pane casts onto the pane pane_below 
 * with the camera delimiting the view.
 * On a classic tile map the bottom is to the south, so this function draws
 * "classic" shadows cast as if the sun were in the south-west,
 * with the shadows pointing north-east.
*/
func (pane * Pane) DrawShadowsOn(pane_below * Pane, camera * physics.Camera) { 
    gridwide := pane.GridW
    gridhigh := pane.GridH
    tilewide := pane.Tileset.TileW
    tilehigh := pane.Tileset.TileH
    x        := int(camera.X)
    y        := int(camera.Y)
    tx_start := x / tilewide
    ty_start := y / tilehigh
    tx_delta := 1 + (int(camera.W) / tilewide)
    ty_delta := 1 + (int(camera.H) / tilehigh)
    tx_stop  := tx_start + tx_delta
    ty_stop  := ty_start + ty_delta
    tx_index := 0
    ty_index := 0
    // realwide := pane.PixelW
    // realhigh := pane.PixelH
    // drawflag := 0
    // al.HoldBitmapDrawing(true)
    if tx_start < 0 { tx_start = 0; }
    if ty_start < 0 { ty_start = 0; }
    if tx_stop  > gridwide { tx_stop = gridwide; }
    if ty_stop  > gridhigh { ty_stop = gridhigh; }
    y_draw    :=  float32(-y + (ty_start * tilehigh))
    for ty_index = ty_start; ty_index < ty_stop; ty_index++ { 
        y_draw   += float32(tilehigh)
        x_draw   := float32(-x + (tx_start * tilewide))
        row      := pane.Cells[ty_index]
        for tx_index = tx_start ; tx_index < tx_stop; tx_index++ {
            x_draw += float32(tilewide)
            cell := &row[tx_index]
            pane.DrawOneShadowOn(cell, pane_below, tx_index, ty_index, x_draw, y_draw) 
        }
    }
    // Let go of hold 
    // al.HoldBitmapDrawing(false)  
}



/** Updates the tile pane. Curently does nothing, but this may change. */
func (pane * Pane) Update(dt float64) {
    if pane.Tileset != nil { 
        pane.Tileset.Update(dt)
    }
}

/** Gets a tile from a the tilepane's tile set by it's tile id. **/
func (pane * Pane)  TileFromSet(index int) * Tile {
    set := pane.Tileset 
    if nil == set { 
        return nil;
    }
    return set.Tile(index)
}


type BlendOffset struct {
  tx int
  ty int
}

var BlendOffsets [8]BlendOffset = [8]BlendOffset{
  {-1, -1}, /* TILE_BLEND_NORTHWEST 0 */ 
  { 0, -1}, /* TILE_BLEND_NORTH     1 */
  { 1, -1}, /* TILE_BLEND_NORTHEAST 2 */
  {-1,  0}, /* TILE_BLEND_WEST      3 */
  { 1,  0}, /* TILE_BLEND_EAST      4 */
  {-1,  1}, /* TILE_BLEND_SOUTHWEST 5 */
  { 0,  1}, /* TILE_BLEND_SOUTH     6 */
  { 1,  1}, /* TILE_BLEND_SOUTHEAST 7 */
}

func (pane * Pane) InitBlendTile(index, tx, ty int, tile * Tile) bool {
    blend := pane.Blend(tx, ty)
    if blend != nil {
        blend.Destroy()
        pane.SetBlend(tx, ty, nil)
    }
    
    target          := al.TargetBitmap()
    tile_prio       := tile.Blend
    for i:= 0; i < len(BlendOffsets) ; i++ {
        offset      := BlendOffsets[i]
        txn         := tx + offset.tx
        tyn         := ty + offset.ty
        aid_tile    := pane.Tile(txn, tyn)
        if aid_tile == nil { continue; }
        aid_prio    := aid_tile.Blend
        if aid_prio <= tile_prio { continue; }
        blend_bmp   := al.CreateBitmap(pane.Tileset.TileW, pane.Tileset.TileH /* , al.CONVERT_BITMAP */)
        if blend_bmp == nil { return false; }
        al.SetTargetBitmap(blend_bmp)
        al.ClearToColor(al.MapRGBA(0,0,0,0))
        PrepareBlend(blend_bmp, tile, aid_tile, i);
    }
    
    al.SetTargetBitmap(target)
    return true
}




const (
    MASK_SIDE_W     = 16
    MASK_SIDE_H     = 16
    MASK_CORNER_W   = 16
    MASK_CORNER_H   = 16
    MASK_W          = 8
    MASK_H          = 8
)

func (pane * Pane) InitMasks() {
    // load the masks into the pane
    for blend_type := 0; blend_type < BLEND_TYPE_MAX ; blend_type++ {
        fin1 := fmt.Sprintf("/image/masks/corner_mask_%d.png", blend_type)
        fin2 := fmt.Sprintf("/image/masks/side_mask_%d.png", blend_type)
 
        bmp1 := fifi.LoadBitmap(fin1)
        bmp2 := fifi.LoadBitmap(fin2)
        BlendMasks[blend_type][BLEND_CORNER]    = bmp1
        BlendMasks[blend_type][BLEND_SIDE]      = bmp2
    }
}

func (pane * Pane) InitBlend(index int) bool {
    if pane == nil        { return false }
    if pane.Blends == nil { return false }
    if index > 4          { return false }
    tx := 0
    ty := 0
    w  := pane.GridW
    h  := pane.GridH
    for ty = 0 ; ty < h; ty++ { 
        for tx = 0; tx < w; tx++ {
            tile := pane.Tile(tx, ty)
            if tile == nil { continue; }
            if tile.Blend < 1 { continue; }
            pane.InitBlendTile(index, tx, ty, tile)
        }
    }
    return true
}