Code: Select all
Structure VECTOR3
x.f
y.f
z.f
EndStructure
OpenWindow(0, 0, 0, 520, 520, "OpenGL Bezier Drawing", #PB_Window_SystemMenu | #PB_Window_ScreenCentered)
If OpenGLGadget(0, 10, 10, 500, 500)
w=GadgetWidth(0) : h=GadgetHeight(0)
glMatrixMode_(#GL_PROJECTION)
glLoadIdentity_()
If (w<=h)
glOrtho_(-5.0, 5.0, -5.0*h / w, 5.0*h / w, -5.0, 5.0)
Else
glOrtho_(-5.0*w / h, 5.0*w / h, -5.0, 5.0, -5.0, 5.0)
EndIf
glMatrixMode_(#GL_MODELVIEW)
glLoadIdentity_()
;// prepare bezier curve data and settings
i=0
Dim bezierPoints.VECTOR3(3)
bezierPoints(i)\x=-4 : bezierPoints(i)\y=-4 : bezierPoints(i)\z=0 : i + 1
bezierPoints(i)\x=-2 : bezierPoints(i)\y=4 : bezierPoints(i)\z=0 : i + 1
bezierPoints(i)\x=2 : bezierPoints(i)\y=-4 : bezierPoints(i)\z=0 : i + 1
bezierPoints(i)\x=4 : bezierPoints(i)\y=4 : bezierPoints(i)\z=0 : i + 1
glClearColor_(0.0, 0.0, 0.0, 0.0)
glShadeModel_(#GL_FLAT)
glMap1f_(#GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4, bezierPoints())
glEnable_(#GL_MAP1_VERTEX_3)
glEnable_(#GL_LINE_STIPPLE) ; it will draw lines with pattern
glEnable_(#GL_LINE_SMOOTH)
glEnable_(#GL_BLEND)
glLineWidth_(3) ; specify line thickness
glLineStipple_(1, $FF00) ; specify dashed pattern
glHint_(#GL_LINE_SMOOTH_HINT, #GL_NICEST)
glBlendFunc_(#GL_SRC_ALPHA, #GL_ONE_MINUS_SRC_ALPHA)
;// The following code displays bezier curve
i=0 : linePrecision=1000
glClear_(#GL_COLOR_BUFFER_BIT)
glColor3f_(1.0, 1.0, 1.0)
glBegin_(#GL_LINE_STRIP)
For i=0 To linePrecision
glEvalCoord1f_(i / linePrecision)
Next
glEnd_()
;// The following code displays the control points As dots.
glPointSize_(5.0);
glColor3f_(1.0, 1.0, 0.0)
glBegin_(#GL_POINTS)
For i=0 To 3
glVertex3fv_(bezierPoints(i))
Next
glEnd_()
glFlush_()
SetGadgetAttribute(0, #PB_OpenGL_FlipBuffers, #True)
EndIf
Repeat: Until WaitWindowEvent()=#PB_Event_CloseWindow
