Draw an arc, pie, or chord
int PgDrawArc( PhPoint_t const *center, PhPoint_t const *radii, unsigned int start, unsigned int end, int flags ); int PgDrawArcCx( void *dc, PhPoint_t const *center, PhPoint_t const *radii, unsigned int start, unsigned int end, int flags );
ph
These functions build a command in the draw buffer to draw an arc. PgDrawArc() works on the current draw context, while you can specify the draw context for PgDrawArcCx().
The arc is drawn counter-clockwise, from the start angle to the end angle. To draw a complete circle, make the two angles equal to each other. An angle of 0 bi-grads is on the horizon to the right of the center.
A circle is divided into 65536 gradations called binary gradations or bi-grads. Thus, 0x2000 is 45 degrees, 0x4000 is 90 degrees, 0x8000 is 180 degrees, and 0xC000 is 270 degrees. |
The flags argument controls what type of arc is drawn:
You can OR one of the following into any flags value:
The following example:
DrawFillArc() { PhPoint_t c = { 80, 60 }; PhPoint_t r = { 72, 52 }; PgSetFillColor( Pg_RED ); PgDrawArc( &c, &r, 0x0000, 0x4000, Pg_DRAW_FILL | Pg_ARC_CHORD); PgSetFillColor( Pg_YELLOW ); PgDrawArc( &c, &r, 0x5555, 0x9555, Pg_DRAW_FILL | Pg_ARC_PIE); PgSetStrokeColor( Pg_WHITE ); PgSetFillColor( Pg_PURPLE ); PgDrawArc( &c, &r, 0xAAAA, 0xEAAA, Pg_DRAW_FILL_STROKE | Pg_ARC_PIE); }
will draw:
The following example:
DrawStrokeArc() { PhPoint_t c = { 80, 60 }; PhPoint_t r = { 72, 52 }; PgSetStrokeColor( Pg_WHITE ); PgDrawArc( &c, &r, 0x0000, 0x4000, Pg_DRAW_STROKE | Pg_ARC_CHORD ); PgSetStrokeColor( Pg_YELLOW ); PgDrawArc( &c, &r, 0x5555, 0x9555, Pg_DRAW_STROKE | Pg_ARC_PIE ); PgSetStrokeColor( Pg_YELLOW ); PgDrawArc( &c, &r, 0xAAAA, 0xEAAA, Pg_DRAW_STROKE | Pg_ARC ); }
will draw:
Photon
Safety: | |
---|---|
Interrupt handler | No |
Signal handler | No |
Thread | No |
To draw stroked arcs, see also:
PgSetStrokeCap*(), PgSetStrokeColor*(), PgSetStrokeDash*(), PgSetStrokeDither*(), PgSetStrokeJoin*(), PgSetStrokeWidth*()
To draw filled arcs, see also:
PgSetFillColor*(), PgSetFillDither*(), PgSetFillTransPat*()
“Arcs, ellipses, polygons, and rectangles” in the Raw Drawing and Animation chapter of the Photon Programmer's Guide