The '''_MAPTRIANGLE''' statement maps a triangular portion of an image to a destination image or screen page.


{{PageSyntax}}
:_MAPTRIANGLE [_SEAMLESS] (''sx1'', ''sy1'')-(''sx2'', ''sy2'')-(''sx3'', ''sy3''), ''source&'', TO (''dx1'', ''dy1'')-(''dx2'', ''dy2'')-(''dx3'', ''dy3'')[, ''destination&'']


* The _SEAMLESS option makes the triangle skip the rightmost and bottommost pixels of the triangle. When you make larger objects using several triangles, there can be a "seam" where they overlap when using alpha transparency and the seam would be twice as bright!
* Graphic triangular coordinates are listed for the ''source'' TO the ''destination'' by column(x) and row(y). 
* Coordinate positions are '''limited to -16383 to 16383!'''  
* If the ''destination'' handle is the [[SCREEN]] page then it can be omitted or 0 can be used.
* The statement is used similar to [[_PUTIMAGE]] to place triangular sections of an image.



''Example 1:'' Rotating an image using a rotation and zoom SUB with _MAPTRIANGLE.
{{CodeStart}} '' ''
{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(800, 600, 32)

Image& = {{Cl|_LOADIMAGE}}("Qb64.png")   '<<< [http://www.qb64.net/forum/index.php Image from top of QB64 Forum]

{{Cl|DO}}
  {{Cl|CLS}}
  RotoZoom 400, 300, Image&, 1.5 + {{Cl|SIN}}(zoom), angle
  {{Cl|LOCATE}} 1, 1: {{Cl|PRINT}} "Angle:"; {{Cl|CINT}}(angle)
  {{Cl|PRINT USING|PRINT}} "Zoom"; {{Cl|PRINT USING|USING}} "##.###"; 1.5 + {{Cl|SIN}}(zoom)
  {{Cl|_DISPLAY}}
  angle = angle + .5: {{Cl|IF...THEN|IF}} angle >= 360 {{Cl|THEN}} angle = angle - 360
  zoom = zoom + .01
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} <> ""
{{Cl|END}}

{{Cl|SUB}} RotoZoom (X {{Cl|AS}} {{Cl|LONG}}, Y {{Cl|AS}} {{Cl|LONG}}, Image {{Cl|AS}} {{Cl|LONG}}, Scale {{Cl|AS}} {{Cl|SINGLE}}, Rotation {{Cl|AS}} {{Cl|SINGLE}})
{{Cl|DIM}} px(3) {{Cl|AS}} {{Cl|SINGLE}}: {{Cl|DIM}} py(3) {{Cl|AS}} {{Cl|SINGLE}}
W& = {{Cl|_WIDTH (function)|_WIDTH}}(Image&): H& = {{Cl|_HEIGHT}}(Image&)
px(0) = -W& / 2: py(0) = -H& / 2: px(1) = -W& / 2:py(1) = H& / 2 
px(2) = W& / 2: py(2) = H& / 2: px(3) = W& / 2: py(3) = -H& / 2
sinr! = {{Cl|SIN}}(-Rotation / 57.2957795131): cosr! = {{Cl|COS}}(-Rotation / 57.2957795131)
{{Cl|FOR...NEXT|FOR}} i& = 0 {{Cl|TO}} 3
  x2& = (px(i&) * cosr! + sinr! * py(i&)) * Scale + X: y2& = (py(i&) * cosr! - px(i&) * sinr!) * Scale + Y
  px(i&) = x2&: py(i&) = y2&
{{Cl|NEXT}}
{{Cl|_MAPTRIANGLE}} (0, 0)-(0, H& - 1)-(W& - 1, H& - 1), Image& TO(px(0), py(0))-(px(1), py(1))-(px(2), py(2))
{{Cl|_MAPTRIANGLE}} (0, 0)-(W& - 1, 0)-(W& - 1, H& - 1), Image& TO(px(0), py(0))-(px(3), py(3))-(px(2), py(2))
{{Cl|END SUB}} '' ''
{{CodeEnd}}
{{small|Code by Galleon}}


''Example 2:'' A 3D Spinning Cube demo using [[_MAPTRIANGLE]]:
{{CodeStart}} '' ''
'
' Copyright (C) 2011 by Andrew L. Ayers
'

{{Cl|DECLARE}} {{Cl|SUB}} DrawHline (fromx%, tox%, yy%, col%)
{{Cl|DECLARE}} {{Cl|SUB}} DrawTriangle (x1%, y1%, x2%, y2%, x3%, y3%, col%)
'
{{Cl|DIM}} OBJECT(9, 9, 4, 2) {{Cl|AS}} {{Cl|LONG}}
'
' OBJECTS DEFINED {{Cl|AS}} FOLLOWS:
'   (#OBJECTS,#PLANES PER OBJECT,#{{Cl|POINT}}S PER PLANE, XYZ TRIPLE)
'
{{Cl|DIM}} DPLANE2D(4, 1) {{Cl|AS}} {{Cl|LONG}} ' {{Cl|SCREEN}} PLANE COORDINATES
'
' DPLANE2D DEFINED {{Cl|AS}} FOLLOWS:
'   (#{{Cl|POINT}}S PER PLANE, XY {{Cl|DOUBLE}})
'
{{Cl|DIM}} DPLANE3D(4, 2) {{Cl|AS}} {{Cl|LONG}} ' 3D PLANE COORDINATES
'
' DPLANE3D DEFINED {{Cl|AS}} FOLLOWS:
'   (#{{Cl|POINT}}S PER PLANE, XYZ TRIPLE)
'
{{Cl|DIM}} PLANECOL(9) {{Cl|AS}} {{Cl|INTEGER}}
'
{{Cl|DIM}} STAB(359), CTAB(359) ' SINE/COSINE TABLES
'
D& = 400: MX& = 0: MY& = 0: MZ& = -100
'
' COMPUTE SINE/COSINE TABLES
'
{{Cl|FOR...NEXT|FOR}} t& = 0 {{Cl|TO}} 359
  STAB(t&) = {{Cl|SIN}}((6.282 / 360) * t&)
  CTAB(t&) = {{Cl|COS}}((6.282 / 360) * t&)
{{Cl|NEXT}}
'
' BUILD CUBE IN OBJECT ARRAY
'
' PLANE 0
OBJECT(0, 0, 0, 0) = -30: OBJECT(0, 0, 0, 1) = 30: OBJECT(0, 0, 0, 2) = -30
OBJECT(0, 0, 1, 0) = -30: OBJECT(0, 0, 1, 1) = -30: OBJECT(0, 0, 1, 2) = -30
OBJECT(0, 0, 2, 0) = 30: OBJECT(0, 0, 2, 1) = -30: OBJECT(0, 0, 2, 2) = -30
OBJECT(0, 0, 3, 0) = 30: OBJECT(0, 0, 3, 1) = 30: OBJECT(0, 0, 3, 2) = -30
OBJECT(0, 0, 4, 0) = 0: OBJECT(0, 0, 4, 1) = 0: OBJECT(0, 0, 4, 2) = -30
'
' PLANE 1
OBJECT(0, 1, 0, 0) = 30: OBJECT(0, 1, 0, 1) = 30: OBJECT(0, 1, 0, 2) = -30
OBJECT(0, 1, 1, 0) = 30: OBJECT(0, 1, 1, 1) = -30: OBJECT(0, 1, 1, 2) = -30
OBJECT(0, 1, 2, 0) = 30: OBJECT(0, 1, 2, 1) = -30: OBJECT(0, 1, 2, 2) = 30
OBJECT(0, 1, 3, 0) = 30: OBJECT(0, 1, 3, 1) = 30: OBJECT(0, 1, 3, 2) = 30
OBJECT(0, 1, 4, 0) = 30: OBJECT(0, 1, 4, 1) = 0: OBJECT(0, 1, 4, 2) = 0
'
' PLANE 2
OBJECT(0, 2, 0, 0) = 30: OBJECT(0, 2, 0, 1) = 30: OBJECT(0, 2, 0, 2) = 30
OBJECT(0, 2, 1, 0) = 30: OBJECT(0, 2, 1, 1) = -30: OBJECT(0, 2, 1, 2) = 30
OBJECT(0, 2, 2, 0) = -30: OBJECT(0, 2, 2, 1) = -30: OBJECT(0, 2, 2, 2) = 30
OBJECT(0, 2, 3, 0) = -30: OBJECT(0, 2, 3, 1) = 30: OBJECT(0, 2, 3, 2) = 30
OBJECT(0, 2, 4, 0) = 0: OBJECT(0, 2, 4, 1) = 0: OBJECT(0, 2, 4, 2) = 30
'
' PLANE 3
OBJECT(0, 3, 0, 0) = -30: OBJECT(0, 3, 0, 1) = 30: OBJECT(0, 3, 0, 2) = 30
OBJECT(0, 3, 1, 0) = -30: OBJECT(0, 3, 1, 1) = -30: OBJECT(0, 3, 1, 2) = 30
OBJECT(0, 3, 2, 0) = -30: OBJECT(0, 3, 2, 1) = -30: OBJECT(0, 3, 2, 2) = -30
OBJECT(0, 3, 3, 0) = -30: OBJECT(0, 3, 3, 1) = 30: OBJECT(0, 3, 3, 2) = -30
OBJECT(0, 3, 4, 0) = -30: OBJECT(0, 3, 4, 1) = 0: OBJECT(0, 3, 4, 2) = 0
'
' PLANE 4
OBJECT(0, 4, 0, 0) = -30: OBJECT(0, 4, 0, 1) = -30: OBJECT(0, 4, 0, 2) = -30
OBJECT(0, 4, 1, 0) = -30: OBJECT(0, 4, 1, 1) = -30: OBJECT(0, 4, 1, 2) = 30
OBJECT(0, 4, 2, 0) = 30: OBJECT(0, 4, 2, 1) = -30: OBJECT(0, 4, 2, 2) = 30
OBJECT(0, 4, 3, 0) = 30: OBJECT(0, 4, 3, 1) = -30: OBJECT(0, 4, 3, 2) = -30
OBJECT(0, 4, 4, 0) = 0: OBJECT(0, 4, 4, 1) = -30: OBJECT(0, 4, 4, 2) = 0
'
' PLANE 5
OBJECT(0, 5, 0, 0) = -30: OBJECT(0, 5, 0, 1) = 30: OBJECT(0, 5, 0, 2) = -30
OBJECT(0, 5, 1, 0) = 30: OBJECT(0, 5, 1, 1) = 30: OBJECT(0, 5, 1, 2) = -30
OBJECT(0, 5, 2, 0) = 30: OBJECT(0, 5, 2, 1) = 30: OBJECT(0, 5, 2, 2) = 30
OBJECT(0, 5, 3, 0) = -30: OBJECT(0, 5, 3, 1) = 30: OBJECT(0, 5, 3, 2) = 30
OBJECT(0, 5, 4, 0) = 0: OBJECT(0, 5, 4, 1) = 30: OBJECT(0, 5, 4, 2) = 0
'
' SET UP PLANE {{Cl|COLOR}}S ON CUBE
'
PLANECOL(0) = 3
PLANECOL(1) = 4
PLANECOL(2) = 5
PLANECOL(3) = 6
PLANECOL(4) = 7
PLANECOL(5) = 8
'
{{Cl|_TITLE}} "QB64 _MAPTRIANGLE CUBE DEMO"
'
{{Cl|SCREEN}} {{Cl|_NEWIMAGE}}(800, 600, 32)
'
TextureImage& = {{Cl|_LOADIMAGE}}("qb64.png") '<<<< [http://www.qb64.net/forum/index.php Image from top of QB64 Forum]
'{{Cl|_PUTIMAGE}} , Image&
'
DO
  '
  ' LIMIT {{Cl|TO}} 25 FPS
  '
  {{Cl|_LIMIT}} 25
  '
  ' {{Cl|ERASE}} LAST IMAGE
  '
  {{Cl|CLS}}
  '
  ' CALCULATE POSITION OF NEW IMAGE
  '
  {{Cl|FOR...NEXT|FOR}} OB& = 0 {{Cl|TO}} 0 ' UP {{Cl|TO}} 9 OBJECTS
    SP = STAB(PIT(OB&)): CP = CTAB(PIT(OB&))
    SY = STAB(YAW(OB&)): CY = CTAB(YAW(OB&))
    SR = STAB(ROL(OB&)): CR = CTAB(ROL(OB&))
    {{Cl|FOR...NEXT|FOR}} PL& = 0 {{Cl|TO}} 5 ' CONSISTING OF UP {{Cl|TO}} 9 PLANES
      '
      {{Cl|FOR...NEXT|FOR}} PN& = 0 {{Cl|TO}} 3 ' EACH PLANE WITH UP {{Cl|TO}} 4 {{Cl|POINT}}S (#5 {{Cl|TO}} {{Cl|PAINT}})
        '
        ' TRANSLATE, {{Cl|THEN}} ROTATE
        '
        TX& = OBJECT(OB&, PL&, PN&, 0)
        TY& = OBJECT(OB&, PL&, PN&, 1)
        TZ& = OBJECT(OB&, PL&, PN&, 2)
        '
        RX& = (TZ& * CP - TY& * SP) * SY - ((TZ& * SP + TY& * CP) * SR + TX& * CR) * CY
        RY& = (TZ& * SP + TY& * CP) * CR - TX& * SR
        RZ& = (TZ& * CP - TY& * SP) * CY + ((TZ& * SP + TY& * CP) * SR + TX& * CR) * SY
        '
        ' ROTATE, {{Cl|THEN}} TRANSLATE
        '
        RX& = RX& + MX&
        RY& = RY& + MY&
        RZ& = RZ& + MZ&
        '
        DPLANE3D(PN&, 0) = RX&: DPLANE3D(PN&, 1) = RY&: DPLANE3D(PN&, 2) = RZ&
        '
        DPLANE2D(PN&, 0) = 399 + (D& * RX& / RZ&)
        DPLANE2D(PN&, 1) = 299 + (D& * RY& / RZ&)
        '
      {{Cl|NEXT}}
      '
      ' CHECK {{Cl|TO}} SEE {{Cl|IF...THEN|IF}} PLANE IS VISIBLE
      '
      x1& = DPLANE3D(0, 0): y1& = DPLANE3D(0, 1): Z1& = DPLANE3D(0, 2)
      x2& = DPLANE3D(1, 0): y2& = DPLANE3D(1, 1): Z2& = DPLANE3D(1, 2)
      x3& = DPLANE3D(2, 0): y3& = DPLANE3D(2, 1): Z3& = DPLANE3D(2, 2)
      '
      T1& = -x1& * (y2& * Z3& - y3& * Z2&)
      T2& = x2& * (y3& * Z1& - y1& * Z3&)
      T3& = x3& * (y1& * Z2& - y2& * Z1&)
      '
      VISIBLE& = T1& - T2& - T3&
      '
      {{Cl|IF...THEN|IF}} VISIBLE& > 0 {{Cl|THEN}}
        '
        ' {{Cl|DRAW}} PLANE
        '
        xx1% = DPLANE2D(0, 0): yy1% = DPLANE2D(0, 1)
        xx2% = DPLANE2D(1, 0): yy2% = DPLANE2D(1, 1)
        xx3% = DPLANE2D(2, 0): yy3% = DPLANE2D(2, 1)
        col% = PLANECOL(PL&)

        {{Cl|_MAPTRIANGLE}} (0, 0)-(0, 255)-(255, 255), TextureImage& TO(xx3%, yy3%)-(xx2%, yy2%)-(xx1%, yy1%)
        '{{Cl|CALL}} DrawTriangle(xx1%, yy1%, xx2%, yy2%, xx3%, yy3%, col%)
        '
        xx1% = DPLANE2D(0, 0): yy1% = DPLANE2D(0, 1)
        xx3% = DPLANE2D(2, 0): yy3% = DPLANE2D(2, 1)
        xx4% = DPLANE2D(3, 0): yy4% = DPLANE2D(3, 1)

        {{Cl|_MAPTRIANGLE}} (0, 0)-(255, 255)-(255, 0), TextureImage& TO(xx3%, yy3%)-(xx1%, yy1%)-(xx4%, yy4%)
        '{{Cl|CALL}} DrawTriangle(xx1%, yy1%, xx3%, yy3%, xx4%, yy4%, col%)
        '
      {{Cl|END IF}}
      '
    {{Cl|NEXT}}
    '
    ' ROTATE OBJECT
    '
    PIT(OB&) = PIT(OB&) + 5
    {{Cl|IF...THEN|IF}} PIT(OB&) > 359 {{Cl|THEN}} PIT(OB&) = 0
    '
    YAW(OB&) = YAW(OB&) + 7
    {{Cl|IF...THEN|IF}} YAW(OB&) > 359 {{Cl|THEN}} YAW(OB&) = 0
    '
    ROL(OB&) = ROL(OB&) + 9
    {{Cl|IF...THEN|IF}} ROL(OB&) > 359 {{Cl|THEN}} ROL(OB&) = 0
    '
  {{Cl|NEXT}}
  '
  ' Calculate Frames per Second
  '
  frames% = frames% + 1
  '
  {{Cl|IF...THEN|IF}} oldtime$ <> {{Cl|TIME$}} {{Cl|THEN}}
    fps% = frames%
    frames% = 1
    oldtime$ = {{Cl|TIME$}}
  {{Cl|END IF}}
  '
  {{Cl|COLOR}} {{Cl|_RGB}}(255, 255, 255): {{Cl|LOCATE}} 1, 1: {{Cl|PRINT}} "FPS :"; fps%
  '
  ' Show Image on Screen
  '
  {{Cl|_DISPLAY}}
  '
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} <> ""
'
{{Cl|WIDTH}} 80: {{Cl|SCREEN}} 0: {{Cl|CLS}}

{{Cl|SUB}} DrawHline (fromx%, tox%, yy%, col%)
  '
  '{{Cl|DEF SEG}} = {{Cl|&H}}A000
  '
  '{{Cl|IF...THEN|IF}} fromx% > tox% {{Cl|THEN}} {{Cl|SWAP}} fromx%, tox%
  '
  'yyy& = yy%
  'sloc& = yyy& * 320 + fromx%
  'eloc& = sloc& + (tox% - fromx%)
  '
  '{{Cl|FOR...NEXT|FOR}} t& = sloc& {{Cl|TO}} eloc&
  '  {{Cl|POKE}} t&, col%
  '{{Cl|NEXT}}
  '
  '{{Cl|DEF SEG}}
  {{Cl|LINE}} (fromx%, yy%)-(tox%, yy%), {{Cl|_RGB}}(255, 255, 255) 'col%
  '
{{Cl|END SUB}}

{{Cl|SUB}} DrawTriangle (x1%, y1%, x2%, y2%, x3%, y3%, col%)
  '
  DO
    sflag% = 0
    {{Cl|IF...THEN|IF}} y1% > y2% {{Cl|THEN}}
      sflag% = 1
      {{Cl|SWAP}} y1%, y2%
      {{Cl|SWAP}} x1%, x2%
    {{Cl|END IF}}
    {{Cl|IF...THEN|IF}} y2% > y3% {{Cl|THEN}}
      sflag% = 1
      {{Cl|SWAP}} y2%, y3%
      {{Cl|SWAP}} x2%, x3%
    {{Cl|END IF}}
  {{Cl|LOOP}} {{Cl|UNTIL}} sflag% = 0
  '
  {{Cl|IF...THEN|IF}} y2% = y3% {{Cl|THEN}}
    '
    ' Draw a flat bottomed triangle
    '
    ydiff1% = y2% - y1%
    ydiff2% = y3% - y1%
    '
    {{Cl|IF...THEN|IF}} ydiff1% <> 0 {{Cl|THEN}}
      slope1! = (x2% - x1%) / ydiff1%
    {{Cl|ELSE}}
      slope1! = 0
    {{Cl|END IF}}
    '
    {{Cl|IF...THEN|IF}} ydiff2% <> 0 {{Cl|THEN}}
      slope2! = (x3% - x1%) / ydiff2%
    {{Cl|ELSE}}
      slope2! = 0
    {{Cl|END IF}}
    '
    sx! = x1%: ex! = x1%
    '
    {{Cl|FOR...NEXT|FOR}} y% = y1% {{Cl|TO}} y2%
      {{Cl|CALL}} DrawHline({{Cl|CINT}}(sx!), {{Cl|CINT}}(ex!), y%, col%)
      sx! = sx! + slope1!
      ex! = ex! + slope2!
    {{Cl|NEXT}}
    '
    {{Cl|EXIT SUB}}
    '
  {{Cl|ELSE}}
    {{Cl|IF...THEN|IF}} y1% = y2% {{Cl|THEN}}
      '
      ' Draw a flat topped triangle
      '
      ydiff1% = y3% - y1%
      ydiff2% = y3% - y2%
      '
      {{Cl|IF...THEN|IF}} ydiff1% <> 0 {{Cl|THEN}}
        slope1! = (x3% - x1%) / ydiff1%
      {{Cl|ELSE}}
        slope1! = 0
      {{Cl|END IF}}
      '
      {{Cl|IF...THEN|IF}} ydiff2% <> 0 {{Cl|THEN}}
        slope2! = (x3% - x2%) / ydiff2%
      {{Cl|ELSE}}
        slope2! = 0
      {{Cl|END IF}}
      '
      sx! = x1%: ex! = x2%
      '
      {{Cl|FOR...NEXT|FOR}} y% = y1% {{Cl|TO}} y3%
        {{Cl|CALL}} DrawHline({{Cl|CINT}}(sx!), {{Cl|CINT}}(ex!), y%, col%)
        sx! = sx! + slope1!
        ex! = ex! + slope2!
      {{Cl|NEXT}}
      '
      x1% = sx!: x2% = ex!
      '
      {{Cl|EXIT SUB}}
      '
    {{Cl|ELSE}}
      '
      ' Draw a general purpose triangle
      '
      '
      ' First draw the flat bottom portion (top half)
      '
      ydiff1% = y2% - y1%
      ydiff2% = y3% - y1%
      '
      {{Cl|IF...THEN|IF}} ydiff1% <> 0 {{Cl|THEN}}
        slope1! = (x2% - x1%) / ydiff1%
      {{Cl|ELSE}}
        slope1! = 0
      {{Cl|END IF}}
      '
      {{Cl|IF...THEN|IF}} ydiff2% <> 0 {{Cl|THEN}}
        slope2! = (x3% - x1%) / ydiff2%
      {{Cl|ELSE}}
        slope2! = 0
      {{Cl|END IF}}
      '
      sx! = x1%: ex! = x1%
      '
      {{Cl|FOR...NEXT|FOR}} y% = y1% {{Cl|TO}} y2%
        {{Cl|CALL}} DrawHline({{Cl|CINT}}(sx!), {{Cl|CINT}}(ex!), y%, col%)
        sx! = sx! + slope1!
        ex! = ex! + slope2!
      {{Cl|NEXT}}
      '
      ' Then draw the flat topped portion (bottom half)
      '
      x1% = x2%
      x2% = ex!
      y1% = y2%
      '
      ydiff1% = y3% - y1%
      ydiff2% = y3% - y2%
      '
      {{Cl|IF...THEN|IF}} ydiff1% <> 0 {{Cl|THEN}}
        slope1! = (x3% - x1%) / ydiff1%
      {{Cl|ELSE}}
        slope1! = 0
      {{Cl|END IF}}
      '
      {{Cl|IF...THEN|IF}} ydiff2% <> 0 {{Cl|THEN}}
        slope2! = (x3% - x2%) / ydiff2%
      {{Cl|ELSE}}
        slope2! = 0
      {{Cl|END IF}}
      '
      sx! = x1%: ex! = x2%
      '
      {{Cl|FOR...NEXT|FOR}} y% = y1% {{Cl|TO}} y3%
        {{Cl|CALL}} DrawHline({{Cl|CINT}}(sx!), {{Cl|CINT}}(ex!), y%, col%)
        sx! = sx! + slope1!
        ex! = ex! + slope2!
      {{Cl|NEXT}}
      '
      x1% = sx!: x2% = ex!
      '
    {{Cl|END IF}}
  {{Cl|END IF}}
  '
{{Cl|END SUB}} '' ''
{{CodeEnd}}{{small|Demo by Andrew L. Ayers}}


''See also:''
* [[_PUTIMAGE]]
* [[SIN]], [[COS]]


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