Created
March 27, 2020 02:55
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bezier
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| static float getApproximationFactor(float angleStart, float angleEnd) { | |
| int arc = angleEnd - angleStart; | |
| if (abs(arc) > M_PI) { | |
| arc -= M_PI * 2; | |
| arc /= M_PI * 2; | |
| } | |
| return (4 / 3) * tan(arc / 4); | |
| } | |
| static void getRelativeControlPoints(float points[], float angleStart, float angleEnd, float radius) { | |
| float factor = getApproximationFactor(angleStart, angleEnd); | |
| float distToCtrPoint = sqrt(radius * radius * (1 + factor * factor)); | |
| float angle1 = angleStart + atan(factor); | |
| float angle2 = angleEnd - atan(factor); | |
| points[0] = cos(angle1) * distToCtrPoint; | |
| points[1] = sin(angle1) * distToCtrPoint; | |
| points[2] = cos(angle2) * distToCtrPoint; | |
| points[3] = sin(angle2) * distToCtrPoint; | |
| } | |
| static void getPointAtAngle(float points[], float angle, float x, float y, float radius) { | |
| points[0] = x + radius * cos(angle); | |
| points[1] = y + radius * sin(angle); | |
| } | |
| static int P5_Arc(lua_State *L) { | |
| float x = luaL_checknumber(L, 1); | |
| float y = luaL_checknumber(L, 2); | |
| float radius = luaL_checknumber(L, 3); | |
| float angleStartRadians = luaL_checknumber(L, 4); | |
| float angleEndRadians = luaL_checknumber(L, 5); | |
| float relControlPoints[4]; | |
| getRelativeControlPoints(relControlPoints, angleStartRadians, angleEndRadians, radius); | |
| float pointStart[2]; | |
| getPointAtAngle(pointStart, angleStartRadians, x, y, radius); | |
| float pointEnd[2]; | |
| getPointAtAngle(pointEnd, angleEndRadians, x, y, radius); | |
| float controlPoint1[] = {x+relControlPoints[0], y+relControlPoints[1]}; | |
| float controlPoint2[] = {x+relControlPoints[2], y+relControlPoints[3]}; | |
| const VGfloat coords[8] = { | |
| pointStart[0], pointStart[1], | |
| controlPoint1[0],controlPoint1[1], | |
| controlPoint2[0],controlPoint2[1], | |
| pointEnd[0],pointEnd[1] | |
| }; | |
| vgModifyPathCoords(arc_path, 0, 2, coords); | |
| if (strokeEnable) | |
| vgDrawPath(arc_path, VG_STROKE_PATH); | |
| return 0; | |
| }; |
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