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Code archives/Graphics/FAST - Scan Line Filled Polygon Function

This code has been declared by its author to be Public Domain code.

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FAST - Scan Line Filled Polygon Function by Andy_A2011
Scan line filling function that works with ANY polygon.

Now included is a more graphical demo on how it might be used. (see second listing) 
;Scan Line Filled Polygon
;public-domain code by Darel Rex Finley, 2007
;http://alienryderflex.com/polygon_fill/
;
;Ported to BlitzPlus
;by Andres Amaya Jr.
;2011.02.27

;polyFill() Demo
;by Andres Amaya Jr.
;2011.03.18

AppTitle "polyFill Demo"
Global sw%, sh%, scrn%
sw = 800: sh = 600
Graphics sw,sh,32,2
SeedRnd MilliSecs()

scrn = CreateImage(sw,sh)
Dim polyX#(500), polyY#(500), nodeX%(500)


Repeat
	intro()
	WaitMouse()
	
	flipper()
	WaitMouse()
	
	tree()
	WaitMouse()
	
	bird()
	WaitKey()

Until KeyHit(1)

FreeImage scrn
End

Function intro()
	Local st%, et%, r%, g%, b%, angle%

	ClsColor 0,65,85
	Cls
	drawGrid()
	st = MilliSecs()	
	LockBuffer BackBuffer()
	starBackground()
	UnlockBuffer BackBuffer()
	et = MilliSecs()-st
	Color 255,255,255
	Text 5,15,"200 differently colored and rotated stars in "+et+"ms"
	Text 460,15,"The spinning star is drawn in real time."
	Text sw/2,sh-30,"Left-Click to continue",1
	GrabImage scrn,0,0
	st = MilliSecs()+1000
	r=255: g=255: b = 128
	While MouseHit(1) = 0
		If st < MilliSecs() Then
			st = MilliSecs()+500
			r = Rand(90,255)
			g = Rand(90,255)
			b = Rand(90,255)
		End If
		DrawBlock  scrn, 0, 0
		mouseStar(r,g,b, MouseX(), MouseY(), Float(angle))
		angle = (angle + 5) Mod 360
		Flip
	Wend
End Function

Function flipper()
	Local numVerts%, oX%, oY%, wide%, high%, x%, y%, st%, et%, et2%
	Local minX#, minY#, maxX#, maxY#

	ClsColor 32,32,160
	Cls
	Restore Dolph
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 128,128,128
	st = MilliSecs()
	LockBuffer BackBuffer()
	polyFill(numVerts, minX, minY, maxX, maxY)
	UnlockBuffer BackBuffer()
	et = MilliSecs()-st
	st = MilliSecs()
	drawPoly(0,0,0, numVerts, 2)
	Color 0,0,0
	Oval 615, 158, 16, 9, True
	et2 = MilliSecs()-st
	Color 255,255,255
	Text 10, 10, "The 143 vertice dolphin polygon, filled in "+et+"ms"
	Text 20, 30, "The thick outline took "+et2+"ms"
	Text sw/2,sh-50,"The next example takes a couple of seconds to render",1
	Text sw/2,sh-30,"Left-Click to continue",1
	Flip
End Function

Function tree()
	Local numVerts%, oX%, oY%, wide%, high%, x%, y%, st%, et%, et2%
	Local minX#, minY#, maxX#, maxY#
	Local r#, g#, b#, dr#, dg#, db#, h#
	
	h = Float(sh)
	r = 255. : g = 200. : b = 10.
	dr = -.99*r/h: dg = -.99*g/h: db = -.99*b/h
	For i = 0 To sh-1
		Color r,g,b
		Line(0,i,sw,i)
		r = r + dr: g = g + dg: b = b + db
	Next
	Restore Tree
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	r = 200: g = 255: b = 90
	dr = -89./90.: dg = -74./75.: db = -77./78
	st = MilliSecs()
	For i= 64 To 5 Step -1
		drawPoly(r, g, b, numVerts, i)
		r = r + dr: g = g + dg: b = b + db
	Next
	et = MilliSecs()-st
	Color 80,80,0
	st = MilliSecs()
	LockBuffer BackBuffer()
	polyFill(numVerts, minX, minY, maxX, maxY)
	UnlockBuffer BackBuffer()
	et2 = MilliSecs()-st

	Color 255, 255, 255
	Text 10,sh-220, "The 418 vertice tree trunk"
	Text 10,sh-205, "polygon was filled in "+et2+"ms"
	Text 5,sh-180, "The green outline took "+et+"ms"
	Text 5,sh-165, "and uses the same polygon definition."
	Text sw/2,sh-30,"Left-Click to continue",1
	Flip
End Function

Function bird()
	Local numVerts%, oX%, oY%, wide%, high%, x%, y%, st%, et%
	Local minX#, minY#, maxX#, maxY#

	ClsColor 80, 180, 255
	Cls
	Restore eagle1
	Read numVerts, oX, oY, wide, high
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x, y
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 68, 68, 0
	
	st = MilliSecs()
	LockBuffer BackBuffer()
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle2
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 83, 83, 0
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle3
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 160,160,120
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle4
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 240, 243, 230
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle5
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 180, 180, 170
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle6
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 240, 200, 65
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle7
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 160, 160, 140
	polyFill(numVerts, minX, minY, maxX, maxY)

	Restore eagle8
	Read numVerts%, oX%, oY%, wide%, high%
	minX = oX : maxX = oX+wide-1
	minY = oY : maxY = oY+high-1
	For i% = 0 To numVerts-1
		Read x%, y%
		polyX(i) = x + oX
		polyY(i) = y + oY
	Next
	Color 240, 230, 100
	polyFill(numVerts, minX, minY, maxX, maxY)
	UnlockBuffer BackBuffer()
	et = MilliSecs()-st
	Color 0,0,0
	Text sw/2,15,"This is a composite drawing of 8 separate polygons",1
	Text sw/2,30,"totaling 607 vertices.",1
	Text sw/2,60,"It took "+et+"ms to render this drawing.",1
	Text sw/2,sh-30,"Press [ESC] to exit",1
	Flip
End Function

Function polyFill(numSides%, minX#, minY#, maxX#, maxY#)
	Local pixelY%, i%, j%, nodes%, b1%, b2%, b3%, b4%, temp%
	Local fpixY#, f1#, f2#, f3#
	
	For pixelY = minY To maxY
		nodes = 0
		j = numSides-1
		fpixY = Float(pixelY)
		;build node list
		For i = 0 To numSides-1
			b1 = polyY(i) < fpixY
			b2 = polyY(j) >= fpixY
			b3 = polyY(j) < fpixY
			b4 = polyY(i) >= fpixY
			If (b1 And b2) Or (b3 And b4) Then
				f1 = fpixY - polyY(i)
				f2 = polyY(j)-polyY(i)
				f3 = polyX(j)-polyX(i)
				nodeX(nodes) = Floor(f1/f2*f3+polyX(i))
				nodes = nodes + 1
			End If
			j = i
		Next
		;sort nodes
		i = 0
		While i < nodes-1
			If nodeX(i)>nodeX(i+1) Then
				temp = nodeX(i)
				nodeX(i) = nodeX(i+1)
				nodeX(i+1) = temp
				If i > 0 Then i = i - 1
			Else
				i = i + 1
			End If
		Wend
		;draw scanline(s)
		For i = 0 To nodes-1 Step 2
			If nodeX(i) <= maxX Then
				If nodeX(i+1) > minX Then
					If nodeX(i) < minX Then nodeX(i) = minX
					If nodeX(i+1) > maxX Then nodeX(i+1) = maxX
					Line nodeX(i),pixelY,nodeX(i+1),pixelY
				End If
			End If
		Next
	Next
End Function
	

Function min#(flt1#, flt2#)
	If flt1 < flt2 Then Return flt1 Else Return flt2
End Function

Function max#(flt1#, flt2#)
	If flt2 > flt1 Then Return flt2 Else Return flt1
End Function

Function drawGrid()
	Local x%, y%
    Color 144,144,144
    For x = 20 To sw-20 Step 20
        Line x,40,x, sh-40
    Next
    For y = 40 To sh-40 Step 20
        Line 20,y,sw-20,y
    Next
End Function

;Draw an outline of the polygon to highlight edges
Function drawPoly(r,g,b, numPoints%, penSize%)
	Local j%, i%
	
	;allow variable line width and color
	If penSize < 1 Then penSize = 1
	Color r,g,b
	
	;draw it!
	j = numPoints-1
	For i = 0 To numPoints-1
		If penSize > 1 Then 
			fatLine(polyX(j), polyY(j), polyX(i), polyY(i), penSize )
		Else
			Line polyX(j), polyY(j), polyX(i), polyY(i)
		End If
		j=i
	Next
End Function

Function starBackground()
	Local i%, starPoints%, penSize%, bigRad%, lilRad%
	Local x%, y%, minX#, minY#, maxX#, maxY#

	For i = 0 To 199
		starPoints = Rand(4,6) 				 ;random number of star points
		penSize = Rand(2, 5) 				 ;random number between 2 and 5 for line width
		bigRad = Rand(15, 20) 				 ;random overall radius of a star between 20 and 40
		lilRad = bigRad * Float((Rand(15, 40))/100.0) ;20 - 50% of big radius
		x = Rand(bigRad+20, sw-bigRad-20) 	 ;keep all of star on screen along X-axis
		y = Rand(bigRad+40, sh-bigRad-40)	 ;...do the same along the Y-axis
		minX = Float(x-bigRad): minY = Float(y-bigRad)
		maxX = Float(x+bigRad): maxY = Float(y+bigRad)
		star(x, y, bigRad, lilRad, starPoints, Rand(0,72))
		Color Rand(0,255), Rand(0,255), Rand(0,255)
		polyFill(starPoints*2, minX, minY, maxX, maxY)
	Next
End Function

Function mouseStar(r%, g%, b%, x%, y%, angle#)
	Local minX#, minY#, maxX#, maxY#
	
	Color r, g, b
	minX = Float(x-20): maxX = Float(x+20)
	minY = Float(y-20): maxY = Float(y+20)
	star(x, y, 20, 8, 5, angle#)
	polyFill(10, minX, minY, maxX, maxY)
End Function
	

Function star(centX#, centY#, outerRad%, innerRad%, points%, startAngle#)
	Local toggle%, element%
	Local inc#, i#

	If (points > 2 And points < 181) And (innerRad <= outerRad) Then
		inc = 360.0/(2.0 * points)
		toggle = 0
		element = 0
		i = startAngle
		While i <= (startAngle + 360.0)
			If toggle Then
				polyX(element) = Cos(i)* innerRad+ centX
				polyY(element) = Sin(i)* innerRad+ centY
			Else
				polyX(element) = Cos(i)* outerRad+ centX
				polyY(element) = Sin(i)* outerRad+ centY
			End If
			toggle = 1 - toggle
			element = element + 1
			i = i + inc
		Wend
	End If
End Function

Function fatLine(x1%, y1%, x2%, y2%, penSize%) 
	Local offset%, deltax%, deltay%, numovals%, d%, x%, y%
	Local dinc1%, dinc2%, xinc1%, xinc2%, yinc1%, yinc2%
	

	If penSize < 1 Then Return False 
	If penSize = 1 Then Line(x1, y1, x2, y2): Return 
	;  penSize% is thickness to draw line 
	offset = penSize / 2          ;offset needed to place Oval correctly

	; Calculate deltax and deltay for initialization
	deltax = Abs(x2 - x1)
	deltay = Abs(y2 - y1)
 
	; Initialize all vars based on which is the independent variable
	If deltax >= deltay Then
	; x is the independent variable
		numovals = deltax + 1
		d = (2 * deltay) - deltax
		dinc1 = deltay Shl 1
		dinc2 = (deltay - deltax) Shl 1
		xinc1 = 1
		xinc2 = 1
		yinc1 = 0
		yinc2 = 1
	Else 
		; y is the independent variable
		numovals = deltay + 1
		d = (2 * deltax) - deltay
		dinc1 = deltax Shl 1
		dinc2 = (deltax - deltay) Shl 1
		xinc1 = 0
		xinc2 = 1
		yinc1 = 1
		yinc2 = 1
	End If
	; Make sure x and y move in the right directions
	If x1 > x2 Then
		xinc1 = - xinc1
		xinc2 = - xinc2
	End If
	If y1 > y2 Then 
		yinc1 = - yinc1
		yinc2 = - yinc2
	End If
	; Start drawing at x, y
	x = x1 - offset
	y = y1 - offset
	; Draw the filled ovals
	For i = 1 To numovals
		Rect x, y, penSize, penSize, True
		If d < 0 Then 
			d = d + dinc1
			x = x + xinc1
			y = y + yinc1
		Else
			d = d + dinc2
			x = x + xinc2
			y = y + yinc2
		End If
	Next
End Function


.Dolph
;==========================================================
;Number of points used to define this polygon
Data 143
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data 70, 50   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 651, 469
;==========================================================
;The 143 coordinate pairs are:
Data 650,161,641,162,629,160,621,157,609,152,594,143,580,134,567,127,535,124,535,126
Data 566,128,580,135,593,143,608,153,620,158,628,161,641,163,650,162,650,166
Data 646,171,640,173,633,170,619,167,606,164,586,161,566,159,510,160,493,160
Data 481,157,476,165,465,177,450,188,432,198,421,203,406,205,386,207,373,208
Data 366,209,360,203,364,200,373,196,382,192,392,183,406,168,414,157,419,153
Data 429,151,419,152,413,156,401,169,285,195,258,202,236,212,200,229,187,235
Data 176,246,164,257,146,282,136,297,126,315,116,330,104,346,98,359,103,364
Data 105,370,105,376,104,386,104,398,101,403,99,408,96,415,93,413,87,409
Data 81,409,78,413,75,418,72,423,67,419,66,410,63,387,64,410,65,423
Data 61,423,58,423,52,423,48,423,41,426,36,433,19,455,15,462,9,468
Data 3,465,4,459,10,443,15,426,26,401,53,367,55,361,56,319,60,289
Data 65,271,83,229,102,191,130,146,160,111,186,78,190,66,192,51,188,39
Data 180,31,173,25,164,19,159,16,158,7,163,2,173,1,192,1,214,4
Data 231,9,245,13,262,21,275,27,287,32,297,33,310,31,338,28,371,28
Data 396,28,435,29,466,32,501,42,526,50,552,62,573,75,588,88,599,100
Data 609,118,614,126,619,132,624,136,632,143,641,148,647,153

.Tree
;==========================================================
;Number of points used to define this polygon
Data 418
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data 170, 30   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 442, 498
;==========================================================
;The 418 coordinate pairs are:
Data 125,494,133,493,144,487,158,484,166,484,161,490,158,494,163,497,180,490,198,482
Data 208,481,206,492,218,488,246,484,264,485,301,487,320,490,339,490,315,474
Data 297,468,268,416,265,404,270,399,279,397,279,382,268,359,265,333,277,323
Data 283,313,291,307,302,302,316,299,326,305,324,317,315,326,301,340,304,352
Data 310,359,324,359,335,355,342,350,340,341,332,349,327,348,322,342,324,329
Data 332,319,337,292,345,290,362,293,381,299,385,306,382,311,359,317,386,315
Data 394,292,388,287,372,284,379,276,389,272,403,272,416,275,428,280,434,289
Data 429,293,419,296,424,301,432,301,441,296,441,285,435,274,424,267,411,263
Data 400,260,405,256,414,255,423,250,430,243,428,237,421,228,409,224,403,226
Data 403,233,405,239,410,233,418,234,418,243,415,248,405,248,400,248,392,249
Data 387,255,386,261,379,263,360,264,346,266,329,278,311,284,279,300,265,307
Data 252,303,255,294,253,283,245,276,244,265,249,256,254,254,263,259,264,267
Data 262,269,257,267,259,276,270,277,277,266,269,251,258,245,243,245,239,257
Data 238,271,240,282,231,275,225,265,233,252,245,233,248,215,257,191,265,173
Data 276,159,288,157,300,161,314,168,322,176,329,194,329,207,325,215,312,218
Data 300,221,322,222,326,227,319,233,342,223,342,205,336,187,336,177,342,178
Data 353,183,359,193,360,202,361,211,372,201,373,186,361,177,351,167,334,162
Data 315,153,308,148,312,131,320,118,331,113,345,113,356,125,355,137,347,141
Data 333,139,344,146,356,145,368,141,371,129,366,117,340,92,326,91,318,99
Data 312,103,307,104,292,99,286,95,280,85,282,77,291,75,299,77,299,81
Data 294,84,307,79,307,71,302,67,292,67,281,67,276,70,271,78,272,89
Data 276,100,285,104,293,110,291,120,286,123,276,126,270,136,268,149,260,154
Data 246,152,241,148,234,142,233,135,237,123,245,119,253,121,253,126,250,131
Data 244,135,248,141,257,139,262,128,269,116,262,104,250,102,239,109,230,118
Data 223,128,223,137,226,148,229,158,239,168,239,181,239,204,231,212,223,222
Data 217,233,214,244,209,250,201,247,194,234,194,203,200,189,207,170,208,152
Data 204,132,197,114,192,93,190,78,196,65,204,55,207,39,214,32,220,33
Data 233,42,243,48,248,58,247,67,245,75,237,76,231,72,229,62,226,52
Data 222,59,224,72,229,82,238,88,249,84,255,74,261,64,255,45,244,31
Data 228,19,207,15,198,27,186,28,170,24,162,18,151,7,143,7,128,6
Data 121,8,121,13,117,19,113,23,109,22,100,17,89,17,95,23,114,28
Data 124,32,131,24,139,20,148,27,163,39,173,39,183,46,183,55,181,63
Data 176,70,173,77,182,100,186,113,189,131,192,155,188,159,177,156,162,141
Data 160,120,159,97,149,86,138,80,116,77,104,68,87,48,71,46,66,49
Data 56,46,52,40,57,33,63,22,46,34,45,46,53,55,61,57,72,57
Data 79,63,91,69,94,76,95,84,91,89,86,92,80,97,79,105,80,117
Data 84,125,85,133,83,143,86,146,95,151,103,151,96,142,95,134,101,133
Data 95,124,91,116,92,101,102,97,120,95,133,97,143,102,147,111,148,123
Data 152,150,172,170,174,191,172,259,167,265,161,257,149,247,138,241,125,235
Data 117,221,110,218,104,209,99,194,88,195,80,189,71,181,56,179,41,179
Data 25,186,15,195,9,205,7,221,8,239,14,244,29,247,38,241,42,227
Data 28,235,22,234,15,224,17,214,19,203,30,195,41,193,55,194,66,197
Data 80,210,89,222,87,231,76,240,64,251,62,259,58,275,63,282,70,292
Data 81,299,95,304,107,302,112,294,110,284,100,293,90,295,83,289,75,282
Data 75,271,78,260,86,253,98,249,109,249,123,250,148,278,165,292,186,304
Data 202,317,215,333,219,351,219,381,217,400,211,417,203,430,185,449,174,455
Data 158,463,139,466,127,475

.eagle1
;==========================================================
;Number of points used to define this polygon
Data 350
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -5, 3   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 792, 530
;==========================================================
;The 350 coordinate pairs are:
Data 81,228,73,226,59,214,45,202,33,184,25,167,17,142,11,123,9,108,6,102
Data 11,96,17,100,19,93,14,76,13,67,13,62,18,55,27,63,33,75
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.eagle2
;==========================================================
;Number of points used to define this polygon
Data 86
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -2, 6   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 477, 441
;==========================================================
;The 86 coordinate pairs are:
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.eagle3
;==========================================================
;Number of points used to define this polygon
Data 45
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -9, -2   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 627, 559
;==========================================================
;The 45 coordinate pairs are:
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.eagle4
;==========================================================
;Number of points used to define this polygon
Data 49
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -12, 0   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 309, 440
;==========================================================
;The 49 coordinate pairs are:
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.eagle5
;==========================================================
;Number of points used to define this polygon
Data 27
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -12, 0   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 274, 442
;==========================================================
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.eagle6    ;beak
;==========================================================
;Number of points used to define this polygon
Data 25
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -21, -3   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 234, 396
;==========================================================
;The 25 coordinate pairs are:
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Data 215,390,204,388,217,385,210,383,202,384,199,389
.eagle7    ;shadow around eye
;==========================================================
;Number of points used to define this polygon
Data 18
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -6, -4   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 250, 392
;==========================================================
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Data 248,387,242,389,229,391,230,387,232,382,227,383,223,381,222,376
.eagle8    ;eye
;==========================================================
;Number of points used to define this polygon
Data 7
;==========================================================
;x & y offsets to place polygon anywhere on screen
Data -6, -4   ;change to appropriate on screen coords
;==========================================================
;width & height of the polygon;s bounding box
Data 233, 378
;==========================================================
;The 7 coordinate pairs are:
Data 232,373,232,376,227,377,224,375,226,373,227,374,230,374

Comments

Andy_A2011
Here's a simple demo that may help others to find a use for this function in their own programs.




BlitzSupport2011
Weird, the demo crashes for me on the intro () function's GrabImage call, saying the image doesn't exist (in debug mode), even if I check for 'scrn = 0' just before that line. Everything looks right to me.


Andy_A2011
Thanks for looking into this.

I've copied and pasted the code from the forum to BlitzPlus a couple of times and had no issues, whether in debug mode or not.

The only other thing is to copy the code in the codebox by right-clicking on the code and choosing [Select All], then press Ctrl-C to copy to clipboard. I'm not trying to be snide or condescending in any way. I'm simply describing the method I'm using to get the code from the forum into BlitzPlus.

As mentioned I did this a couple of times and have had no problems.

Looking at the code some more.... Maybe because you are using Blitz3D instead of B+, you may want to move the "LockBuffer BackBuffer()" in the intro() function one line down. This will draw the "starBackground()" function before the buffer is locked. The only reason that I mention this is that I've notice that "Oval()" doesn't work in B+ when the buffer is locked. Notice in this demo "Oval() is always drawn before or after locking/unlocking the buffer. Perhaps Blitz3D has a similar 'feature' when drawing graphic primitives when the buffer is locked, or in this instance "GrabImage()".

If neither of the above suggestions work, let me know and I'll dig deeper.


Andy_A2011
Ok, you're most definitely using Blitz3D.

I DL'd the Blitz3D demo and got the same error you're getting.

The demo seems to run if you make the following changes for Blitz3D.

(although very slowly - In B+ I get a rendering time of 10ms for the stars background, 5ms for the dolphin polygon, and 13ms for the dolphin outline)


1) The line: scrn = CreateImage sw, sh needs changing to: scrn = CreateImage 800, 600. It's located just above the DIM statement near the top of the listing.

2) Cut that line and Paste directly into the intro() function (just below 'Local' declarations should be fine).

I also changed the 'Flip' statement to the 2 line version: VWait : Flip False

I only tested on the first two screens because the demo version (Blitz3D v1.83) only allows 16K of code. Which means I had to delete all references to the other two demo screens.

If you get this to work for you, could you post a version for B3D?


Floyd2011
The "Image does not exist" problem happens because of the Graphics command AFTER CreateImage.

Simply move the CreateImage command so it follows Graphics.


Andy_A2011
Thanks Floyd, that did the trick.

Just one more change to allow the timing text to display.

Change this:


to this:



BlitzSupport2011
Well done, sorted now. Very quick polyfiller!


Andy_A2011
Thanks!

Hopefully someone finds a use for this fast poly fill. I think it is probably a quick triangle filler as well. Maybe somebody like Devil's Child could test it in his software only renderer.


Jur2012
Here is the function in BlitzMax. It returns an array of x intervals for every y line ( [y][xInterval1Start,xInterval1End, ...])




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