Bitmap/Bézier curves/Quadratic: Difference between revisions

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Using the data storage type defined [[Basic_bitmap_storage|on this page]] for raster images, and the <tt>draw_line</tt> function defined in [[Bresenham's_line_algorithm|this one]], draw a ''quadratic bezier ~~curves~~''

Using the data storage type defined [[Basic_bitmap_storage|on this page]] for raster images, and the <tt>draw_line</tt> function defined in [[Bresenham's_line_algorithm|this one]], draw a ''quadratic bezier curve''

([[wp:Bezier_curves#Quadratic_B.C3.A9zier_curves|definition on Wikipedia]]).

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}

return</lang>

=={{header|XPL0}}==

[[File:QuadXPL0.png|right]]

<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations

proc Bezier(P0, P1, P2); \Draw quadratic Bezier curve

real P0, P1, P2;

def Segments = 8;

int I;

real T, A, B, C, X, Y;

[Move(fix(P0(0)), fix(P0(1)));

for I:= 1 to Segments do

[T:= float(I)/float(Segments);

A:= sq(1.-T);

B:= 2.*T*(1.-T);

C:= sq(T);

X:= A*P0(0) + B*P1(0) + C*P2(0);

Y:= A*P0(1) + B*P1(1) + C*P2(1);

Line(fix(X), fix(Y), $00FFFF); \cyan line segments

];

Point(fix(P0(0)), fix(P0(1)), $FF0000); \red control points

Point(fix(P1(0)), fix(P1(1)), $FF0000);

Point(fix(P2(0)), fix(P2(1)), $FF0000);

];

[SetVid($112); \set 640x480x24 video graphics

Bezier([0., 0.], [80., 100.], [160., 20.]);

if ChIn(1) then []; \wait for keystroke

SetVid(3); \restore normal text display

]</lang>