add template diagrams to FormDiagram

Author: ricardoavelino

src/compas_tna/diagrams/diagram.py

@@ -1,5 +1,39 @@
 from compas.datastructures import Mesh
+from compas.geometry import angle_vectors
 
 
 class Diagram(Mesh):
     """Base diagram implementing attributes shared between the form and force diagram."""
+
+    def corner_vertices(self, tol=160):
+        """
+        Identify the corner vertices.
+
+        Parameters
+        ----------
+        mesh : Mesh
+            The mesh to analyze
+        tol : float, optional
+            The threshold value for the angle formed between two edges at a vertex
+            for it to be considered a corner.
+            Vertices with smaller angles are considered a corner.
+
+        Returns
+        -------
+        list[int]
+
+        """
+        vkeys = []
+        for key in self.vertices_on_boundary():
+            if self.vertex_degree(key) == 2:
+                vkeys.append(key)
+            else:
+                nbrs = []
+                for nkey in self.vertex_neighbors(key):
+                    if self.is_edge_on_boundary((key, nkey)):
+                        nbrs.append(nkey)
+                u = self.edge_vector((key, nbrs[0]))
+                v = self.edge_vector((key, nbrs[1]))
+                if angle_vectors(u, v, deg=True) < tol:
+                    vkeys.append(key)
+        return vkeys

src/compas_tna/diagrams/diagram_arch.py

@@ -0,0 +1,92 @@
+import math
+
+from numpy import linspace
+
+from compas.geometry import Point
+from compas.tolerance import TOL
+from compas.datastructures import Mesh
+
+
+def create_arch_form_diagram(
+    H: float = 1.0,
+    L: float = 2.0,
+    x0: float = 0.0,
+    discretisation: int = 100,
+) -> Mesh:
+    """Construct a FormDiagram based on an arch linear discretisation.
+    Note: The nodes of the form diagram are spaced following a projection in a semicircular arch.
+
+    Parameters
+    ----------
+    H : float, optional
+        Height of the arch, by default 1.00
+    L : float, optional
+        Span of the arch, by default 2.00
+    x0 : float, optional
+        Initial coordiante of the arch, by default 0.0
+    discretisation : int, optional
+        Numbers of nodes to be considered in the form diagram, by default 100
+
+    Returns
+    -------
+    :class:`~compas_tno.diagrams.FormDiagram`
+        The FormDiagram created.
+
+    """
+    # Add option for starting from Hi and Li for a given thk.
+    radius = H / 2 + (L**2 / (8 * H))
+    spr = math.atan2((L / 2), (radius - H))
+    tot_angle = 2 * spr
+    angle_init = (math.pi - tot_angle) / 2
+    an = tot_angle / (discretisation - 1)
+
+    lines = []
+
+    for i in range(discretisation - 1):
+        angle_i = angle_init + i * an
+        angle_f = angle_init + (i + 1) * an
+        xi = L / 2 - radius * math.cos(angle_i) + x0
+        xf = L / 2 - radius * math.cos(angle_f) + x0
+
+        lines.append([[xi, 0.0, 0.0], [xf, 0.0, 0.0]])
+        
+    form = Mesh.from_lines(lines)
+
+    return form
+
+
+def create_linear_form_diagram(
+    L: float = 2.0,
+    x0: float = 0.0,
+    discretisation: int = 100,
+) -> Mesh:
+    """Helper to create a arch linear form-diagram with equaly spaced (in 2D) nodes.
+
+    Parameters
+    ----------
+    L : float, optional
+        Span of the arch, by default 2.00
+    x0 : float, optional
+        Initial coordiante of the arch, by default 0.0
+    discretisation : int, optional
+        Numbers of nodes to be considered in the form diagram, by default 100
+
+    Returns
+    -------
+    :class:`~compas_tno.diagrams.FormDiagram`
+        FormDiagram generated according to the parameters.
+
+    """
+    x = linspace(x0, x0 + L, discretisation)  # Continue this remove need of numpy in the future
+    lines = []
+    
+    for i in range(discretisation - 1):
+        xi = x[i]
+        xf = x[i + 1]
+
+        lines.append([[xi, 0.0, 0.0], [xf, 0.0, 0.0]])
+
+    form = Mesh.from_lines(lines)
+
+    return form
+