Procedure.f GradientCallback(x, y)
;
; Return a value between 0.0 and 1.0 to define the gradient for the x/y position.
;
ProcedureReturn 1.0
EndProcedure
The callback will be called for every pixel that is part of a drawing operation. The callback
has to return a value between 0.0 and 1.0 (not a color value) to define the gradient value at the given position.
By default the value 0.0 represents the current background color and the value 1.0 represents the current front color. Additional colors can be added to the gradient with the GradientColor() command.
This callback will be called many times (for every pixel to draw) so it should be very small and fast to not have a too big impact on the drawing performance.
Note: This command only has an effect with ImageOutput(). The gradient only affects the drawing commands when #PB_2DDrawing_Gradient is set with the DrawingMode() command.
Example:
Procedure.f GradientCallback(x, y)
ProcedureReturn Sin(x * 0.1) * Sin(y * 0.1) ; will be between 0 and 1
EndProcedure
If OpenWindow(0, 0, 0, 400, 200, "2DDrawing Example", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
If CreateImage(0, 400, 200) And StartDrawing(ImageOutput(0))
Box(0, 0, 400, 200, $FFFFFF)
DrawingMode(#PB_2DDrawing_Gradient)
BackColor($00FFFF)
FrontColor($FF0000)
CustomGradient(@GradientCallback())
Circle(100, 100, 100)
Circle(300, 100, 100)
StopDrawing()
ImageGadget(0, 0, 0, 400, 200, ImageID(0))
EndIf
Repeat
Event = WaitWindowEvent()
Until Event = #PB_Event_CloseWindow
EndIf
