Alternate to DrawPoly?

BlitzMax Forums/BlitzMax Programming/Alternate to DrawPoly?

Odds On (Posted 2007) [#1]

I'm having some problems with the built-in DrawPoly method.. as you can see from the code example below, there is a large ugly white triangle (caused by overlapping polygons) that shouldn't be there. Graphics 800, 600 SetBlend alphablend While Not KeyHit( KEY_ESCAPE ) = True Cls Local poly:Float[] = [0.0, 200.0, 0.0, 0.0, 200.0, 0.0, 200.0, 100.0, 100.0, 100.0, 100.0, 200.0] SetOrigin 400, 300 SetColor 255, 255, 255 SetAlpha 0.5 DrawPoly poly SetColor 255, 0, 0 SetAlpha 1.0 For i = 0 Until poly.length Step 2 DrawOval poly[i] - 2, poly[i+1] - 2, 4, 4 Next Flip Wend End Does anyone have any alternatives to DrawPoly that produce more reliable results? Thanks, Chris

H&K (Posted 2007) [#2]

'==================================================================================================== ' File Name: Type_TShapeBit.Bmx '---------------------------------------------------------------------------------------------------- ' Type Description: So that I can have concave shapes a bit of a shape '---------------------------------------------------------------------------------------------------- ' History ' 1.00 Created '==================================================================================================== Type TShapeBit 'Bit of a shape '---------------------------------------------- Field F_PointsArray :Float[] Field F_NumberOfPoints :Int '---------------------------------------------- Function RF_CreateFromArray:TShapeBit(P_Array:Float[]) Local Temp :TShapeBit = New TShapeBit.RM_SetFromArray(P_Array) Return Temp End Function '---------------------------------------------- Function RF_CreateFromFloats:TShapeBit(P_X:Float,P_Y:Float) Local Temp:TShapeBit = New TShapeBit.RM_SetFromFloats(P_X,P_Y) Return Temp End Function '---------------------------------------------- Method RM_SetFromArray:TShapeBit(P_Array:Float[]) F_PointsArray = P_Array F_NumberOfPoints = SizeOf(P_Array)/8 Return Self End Method '---------------------------------------------- Method RM_SetFromFloats:TShapeBit(P_X:Float,P_Y:Float) F_PointsArray = New Float[2] F_PointsArray[0] = P_X F_PointsArray[1] = P_Y F_NumberOfPoints = 1 Return Self End Method '---------------------------------------------- Method SM_AddFloats (P_X:Float,P_Y:Float) F_NumberOfPoints:+ 1 F_PointsArray = F_PointsArray[ ..(F_NumberOfPoints * 2)] F_PointsArray[(F_NumberOfPoints*2)-2] = P_X F_PointsArray[(F_NumberOfPoints*2)-1] = P_Y End Method '---------------------------------------------- Method DM_Draw () DrawPoly F_PointsArray End Method '---------------------------------------------- Method SM_ReSizeFloats(P_MultiX:Float,P_MultiY:Float) For Local Loop:Int = 0 To (F_NumberOfPoints-1)*2 Step 2 F_PointsArray[Loop]:* P_MultiX F_PointsArray[Loop+1]:* P_MultiY Next End Method '---------------------------------------------- Method SM_Scale(P_Scale:Float) SM_ReSizeFloats(P_Scale,P_Scale) End Method '---------------------------------------------- Method SM_FlipHoriz() For Local Loop:Int = 0 To (F_NumberOfPoints-1)*2 Step 2 F_PointsArray[Loop+1]:* -1 Next End Method '---------------------------------------------- Method SM_FlipVert() For Local Loop:Int = 0 To (F_NumberOfPoints-1)*2 Step 2 F_PointsArray[Loop]:*-1 Next End Method '---------------------------------------------- EndType '==================================================================================================== '==================================================================================================== ' File Name: Type_TShape.Bmx '---------------------------------------------------------------------------------------------------- ' Type Description: Concave filled shape '---------------------------------------------------------------------------------------------------- ' History ' 1.00 Created '==================================================================================================== Type TShape 'Concave filled shape '------------------------------------------------------- Field F_BitArray :TShapeBit[] Field F_NumberOfBits :Int ' Number of Points in shape '---------------------------------------------- Function RF_CreateFromArray:TShape (P_Array:Float[]) Local Temp:TShape = New TShape.RM_SetFromArray(P_Array) Return Temp End Function '---------------------------------------------- Function RF_CreateFromFloats:TShape(P_X:Float,P_Y:Float) Local Temp:TShape = New TShape.RM_SetFromFloats(P_X,P_Y) Return Temp End Function '---------------------------------------------- Method RM_SetFromArray:TShape (P_Array:Float[]) Self.F_BitArray = New TShapeBit[1] Self.F_BitArray[0] = TShapeBit.RF_CreateFromArray(P_Array) Self.F_NumberOfBits = 1 Return Self End Method '---------------------------------------------- Method RM_SetFromFloats:TShape(P_X:Int,P_Y:Int) Self.F_BitArray = New TShapeBit[1] Self.F_BitArray[0] = TShapeBit.RF_CreateFromFloats(P_X,P_Y) Self.F_NumberOfBits = 1 End Method '---------------------------------------------- Method SM_NextPolyFloats(P_X:Int,P_Y:Int) Self.F_NumberOfBits:+1 Self.F_BitArray = Self.F_BitArray[.. Self.F_NumberOfBits] Self.F_BitArray[Self.F_NumberOfBits-1] = TShapeBit.RF_CreateFromFloats(P_X,P_Y) End Method '---------------------------------------------- Method SM_AddFloats (P_X:Int,P_Y:Int) Self.F_BitArray[Self.F_NumberOfBits-1].SM_AddFloats(P_X,P_Y) End Method '---------------------------------------------- Method DM_Draw () For Local Loop:Int = 0 To Self.F_NumberOfBits-1 Self.F_BitArray[Loop].DM_Draw() Next End Method '---------------------------------------------- Method SM_ReSizeFloats(P_X:Float,P_Y:Float) For Local Loop:Int = 0 To Self.F_NumberOfBits-1 Self.F_BitArray[Loop].SM_ReSizeFloats(P_X,P_Y) Next End Method '---------------------------------------------- Method SM_Scale(P_Multi:Float) For Local Loop:Int = 0 To Self.F_NumberOfBits-1 Self.F_BitArray[Loop].SM_Scale(P_Multi) Next End Method '---------------------------------------------- EndType '====================================================================================================

Odds On (Posted 2007) [#3]

Thanks for that H&K, I threw together a quick test to see if it works, but it seems to produce exactly the same results as DrawPoly(). In my main program, the points are plotted by clicking the mouse onto a grid, so any kind of wierd and wonderful shape could be created.. From looking at the code, it looks like the shape is split into smaller pieces, but it doesn't appear to be an automatic process. Any more information regarding the code above would be appreciated. Thanks, Chris

H&K (Posted 2007) [#4]

You have to split the poly into only convex parts. That is each shapebit should be convex. Its totly useless for your auto thingy, as the bits need to be pre calculated