Merge 36733b0 into ccf4f61

pymech/meshplot.py

@@ -0,0 +1,305 @@
+import wx
+from wx import glcanvas
+from OpenGL.GL import (
+    glViewport,
+    glMatrixMode,
+    glClearColor,
+    glClear,
+    glLoadIdentity,
+    glOrtho,
+    glEnable,
+    glLineWidth,
+    glBegin,
+    glEnd,
+    glColor,
+    glVertex3fv,
+    GL_PROJECTION,
+    GL_COLOR_BUFFER_BIT,
+    GL_LINE_SMOOTH,
+    GL_MODELVIEW,
+    GL_LINES,
+)
+from math import sqrt, atan2, asin, cos, sin
+
+
+class MeshFrame(wx.Frame):
+    """
+    A frame to display meshes
+    """
+
+    def __init__(
+        self,
+        mesh,
+        parent,
+        id,
+        title,
+        pos=wx.DefaultPosition,
+        size=wx.DefaultSize,
+        style=wx.DEFAULT_FRAME_STYLE,
+        name="frame",
+    ):
+        super(MeshFrame, self).__init__(parent, id, title, pos, size, style, name)
+        self.GLinitialized = False
+        attribList = (
+            glcanvas.WX_GL_RGBA,  # RGBA
+            glcanvas.WX_GL_DOUBLEBUFFER,  # Double Buffered
+            glcanvas.WX_GL_DEPTH_SIZE,
+            24,
+        )  # 24 bit
+
+        # Create the canvas
+        self.canvas = glcanvas.GLCanvas(self, attribList=attribList)
+        self.context = glcanvas.GLContext(self.canvas)
+
+        # Set the event handlers.
+        self.canvas.Bind(wx.EVT_ERASE_BACKGROUND, self.processEraseBackgroundEvent)
+        self.canvas.Bind(wx.EVT_SIZE, self.processSizeEvent)
+        self.canvas.Bind(wx.EVT_PAINT, self.processPaintEvent)
+
+        # create a menu bar
+        # self.makeMenuBar()
+
+        # mesh display properties
+        self.curve_points = 12
+
+        # data to be drawn
+        self.vertices = []
+        self.edges = []
+        self.buildMesh(mesh)
+
+        # view parameters
+        self.margins = 0.05
+        # sets self.mesh_limits
+        self.setLimits(mesh)
+        # current limits
+        self.limits = self.mesh_limits
+
+        # and a status bar
+        # self.CreateStatusBar()
+        # self.SetStatusText("initialised")
+
+    # Canvas Proxy Methods
+
+    def GetGLExtents(self):
+        """Get the extents of the OpenGL canvas."""
+        return self.canvas.GetClientSize()
+
+    def SwapBuffers(self):
+        """Swap the OpenGL buffers."""
+        self.canvas.SwapBuffers()
+
+    def OnExit(self, event):
+        """Close the frame, terminating the application."""
+        self.Close(True)
+
+    # wxPython Window Handlers
+
+    def processEraseBackgroundEvent(self, event):
+        """Process the erase background event."""
+        pass  # Do nothing, to avoid flashing on MSWin
+
+    def processSizeEvent(self, event):
+        """Process the resize event."""
+        if self.context:
+            # Make sure the frame is shown before calling SetCurrent.
+            self.Show()
+            self.canvas.SetCurrent(self.context)
+
+            size = self.GetGLExtents()
+            self.OnReshape(size.width, size.height)
+            self.canvas.Refresh(False)
+        event.Skip()
+
+    def processPaintEvent(self, event):
+        """Process the drawing event."""
+        self.canvas.SetCurrent(self.context)
+
+        # This is a 'perfect' time to initialize OpenGL ... only if we need to
+        if not self.GLinitialized:
+            self.OnInitGL()
+            self.GLinitialized = True
+
+        self.OnDraw()
+        event.Skip()
+
+    # GLFrame OpenGL Event Handlers
+
+    def OnInitGL(self):
+        """Initialize OpenGL for use in the window."""
+        glClearColor(1, 1, 1, 1)
+
+    def OnReshape(self, width, height):
+        """Reshape the OpenGL viewport based on the dimensions of the window."""
+
+        xmin = self.limits[0]
+        xmax = self.limits[1]
+        ymin = self.limits[2]
+        ymax = self.limits[3]
+        # check whether the view is limited by width or height, and scale accordingly
+        lx = xmax - xmin
+        ly = ymax - ymin
+        if lx / width > ly / height:
+            y0 = 0.5 * (ymin + ymax)
+            dy = height / width * lx / 2
+            ymin = y0 - dy
+            ymax = y0 + dy
+        else:
+            x0 = 0.5 * (xmin + xmax)
+            dx = width / height * ly / 2
+            xmin = x0 - dx
+            xmax = x0 + dx
+        glViewport(0, 0, width, height)
+        glMatrixMode(GL_PROJECTION)
+        glLoadIdentity()
+        glOrtho(xmin, xmax, ymin, ymax, -1, 1)
+
+        glMatrixMode(GL_MODELVIEW)
+        glLoadIdentity()
+
+    def OnDraw(self, *args, **kwargs):
+        "Draw the window."
+        glClear(GL_COLOR_BUFFER_BIT)
+        glEnable(
+            GL_LINE_SMOOTH
+        )  # this doesn't seem to be doing anything? It would be nice to have antialiasing
+        glLineWidth(1.0)
+        glBegin(GL_LINES)
+        glColor(0, 0, 0)
+        for edge in self.edges:
+            for vertex in edge:
+                glVertex3fv(self.vertices[vertex])
+        glEnd()
+
+        self.SwapBuffers()
+
+    def buildMesh(self, mesh):
+        """
+        Builds the edges to be drawn based on the mesh representation.
+        """
+
+        # gives the indices of the vertices of an element in a position array
+        def vertex_indices(iface):
+            if iface == 0:
+                return (0, 0)
+            elif iface == 1:
+                return (0, -1)
+            elif iface == 2:
+                return (-1, -1)
+            else:
+                return (-1, 0)
+
+        current_point = 0
+        first_point = 0
+        for el in mesh.elem:
+            first_point = current_point
+            for iface in range(4):
+                j0, i0 = vertex_indices(iface)
+                if el.ccurv[iface] == "":
+                    self.vertices.append(
+                        (
+                            el.pos[0, 0, j0, i0],
+                            el.pos[1, 0, j0, i0],
+                            0.0,
+                        )
+                    )
+                    if iface < 3:
+                        next_point = current_point + 1
+                    else:
+                        next_point = first_point
+                    self.edges.append((current_point, next_point))
+                    current_point += 1
+                elif el.ccurv[iface] == "m":
+                    # we should draw a parabola passing through the current vertex, the midpoint, and the next vertex.
+                    x0, y0 = el.pos[0:2, 0, j0, i0]
+                    xm, ym = el.curv[iface][0:2]
+                    j1, i1 = vertex_indices((iface + 1) % 4)
+                    x1, y1 = el.pos[0:2, 0, j1, i1]
+                    # quadratic Lagrange interpolation between points
+                    for ipt in range(self.curve_points):
+                        # tp varies between 0 and 1
+                        tp = ipt / self.curve_points
+                        xp = (
+                            x0 * 2 * (tp - 0.5) * (tp - 1)
+                            - xm * 4 * tp * (tp - 1)
+                            + x1 * 2 * tp * (tp - 0.5)
+                        )
+                        yp = (
+                            y0 * 2 * (tp - 0.5) * (tp - 1)
+                            - ym * 4 * tp * (tp - 1)
+                            + y1 * 2 * tp * (tp - 0.5)
+                        )
+                        self.vertices.append((xp, yp, 0))
+                        if iface == 3 and ipt == self.curve_points - 1:
+                            next_point = first_point
+                        else:
+                            next_point = current_point + 1
+                        self.edges.append((current_point, next_point))
+                        current_point += 1
+                elif el.ccurv[iface] == "C":
+                    # draw a circle of given radius passing through the next vertex and the current one
+                    # first, find the distance between the midpoint of the segment ((x0, y0), (x1, y1)) and the center (xc, yc) of the circle
+                    radius = el.curv[iface][
+                        0
+                    ]  # this can be positive or negative depending on direction
+                    x0, y0 = el.pos[0:2, 0, j0, i0]
+                    j1, i1 = vertex_indices((iface + 1) % 4)
+                    x1, y1 = el.pos[0:2, 0, j1, i1]
+                    # length of the segment
+                    ls2 = (x1 - x0) ** 2 + (y1 - y0) ** 2
+                    try:
+                        dist = radius * sqrt(1 - ls2 / (4 * radius**2))
+                    except ValueError:
+                        raise ValueError("the radius of the curved edge is too small")
+                    # midpoint of the edge
+                    xm = 0.5 * (x0 + x1)
+                    ym = 0.5 * (y0 + y1)
+                    # outward normal direction
+                    ls = sqrt(ls2)
+                    nx = (y1 - y0) / ls
+                    ny = -(x1 - x0) / ls
+                    # position of the centre
+                    xc = xm - nx * dist
+                    yc = ym - ny * dist
+                    # now find the range of arguments spanned by the circle arc
+                    # argument to the centre of the edge
+                    theta0 = atan2(ym - yc, xm - xc)
+                    dtheta = asin(ls / (2 * radius))
+                    theta_min = theta0 - dtheta
+                    # Now, add the points
+                    for itheta in range(self.curve_points):
+                        theta = theta_min + 2 * dtheta * itheta / self.curve_points
+                        xp = xc + abs(radius) * cos(theta)
+                        yp = yc + abs(radius) * sin(theta)
+                        self.vertices.append((xp, yp, 0))
+                        if iface == 3 and itheta == self.curve_points - 1:
+                            next_point = first_point
+                        else:
+                            next_point = current_point + 1
+                        self.edges.append((current_point, next_point))
+                        current_point += 1
+
+    def setLimits(self, mesh):
+        """
+        set view limits to the size of the mesh with some margin
+        """
+        xmin, xmax = mesh.lims.pos[0]
+        ymin, ymax = mesh.lims.pos[1]
+        lx = xmax - xmin
+        ly = ymax - ymin
+        self.mesh_limits = [
+            xmin - self.margins * lx,
+            xmax + self.margins * lx,
+            ymin - self.margins * ly,
+            ymax + self.margins * ly,
+        ]
+
+
+def plot2D(mesh):
+    # make a new app & frame
+    app = wx.App()
+    frame = MeshFrame(mesh, None, -1, title="pymech")
+
+    frame.Show()
+
+    # Start the event loop.
+    app.MainLoop()