Start adding grid

src/mesh/MeshPrimitives.cpp

@@ -0,0 +1,90 @@
+#include "MeshPrimitives.h"
+
+#include <iostream>
+
+std::unique_ptr<TriMesh> MeshPrimitives::build(const Rectangle& rectangle)
+{
+    const auto bottom_left = rectangle.getLocation();
+    const auto width = rectangle.getWidth();
+    const auto height = rectangle.getHeight();
+
+    VecPoints locations = {
+            bottom_left,
+            Point(bottom_left, width, 0),
+            Point(bottom_left, width, height),
+            Point(bottom_left, 0, height)
+    };
+
+    EdgeIds edge_ids = {
+            {0, 1},
+            {1, 2},
+            {2, 0},
+            {2, 3},
+            {3, 0}
+    };
+
+    FaceIds face_ids = {
+            {0, 1, 2},
+            {2, 3, 4}
+    };
+
+    return MeshBuilder::buildTriMesh(locations, edge_ids, face_ids);
+}
+
+std::unique_ptr<TriMesh> MeshPrimitives::buildExplodedGrid(unsigned numX, unsigned numY)
+{
+    double delta_x = 1.0/double(numX);
+    double delta_y = 1.0/double(numY);
+
+    VecPoints locations (4 * numX * numY);
+    double offset_x = delta_x;
+    double offset_y = delta_y;
+    for (unsigned idx=0; idx<numY; idx++)
+    {
+        for(unsigned jdx=0; jdx<numX; jdx++)
+        {
+            auto locX0 = offset_x - delta_x/2.0;
+            auto locX1 = offset_x + delta_x/2.0;
+            auto locY0 = offset_y - delta_y/2.0;
+            auto locY1 = offset_y + delta_y/2.0;
+
+            auto id_offset = 4* (jdx + numX*idx);
+            locations[id_offset] = Point(locX0, locY0);
+            locations[id_offset + 1] = Point(locX1, locY0);
+            locations[id_offset + 2] = Point(locX1, locY1);
+            locations[id_offset + 3] = Point(locX0, locY1);
+            offset_x += delta_x;
+        }
+        offset_x = delta_x;
+        offset_y += delta_y;
+    }
+
+    EdgeIds edge_ids(5 * numX * numY);
+    for (unsigned idx=0; idx<numY; idx++)
+    {
+        for(unsigned jdx=0; jdx<numX; jdx++)
+        {
+            unsigned node_offset = 4 * (jdx + numX * idx);
+            auto id_offset = 5* (jdx + numX*idx);
+            edge_ids[id_offset] = {node_offset, node_offset + 1};
+            edge_ids[id_offset + 1] = {node_offset + 1, node_offset + 2};
+            edge_ids[id_offset + 2] = {node_offset + 2, node_offset + 3};
+            edge_ids[id_offset + 3] = {node_offset + 3, node_offset};
+            edge_ids[id_offset + 4] = {node_offset + 2, node_offset};
+        }
+    }
+
+    FaceIds face_ids(2 *numX * numY);
+    for (unsigned idx=0; idx<numY; idx++)
+    {
+        for(unsigned jdx=0; jdx<numX; jdx++)
+        {
+            unsigned edge_offset = 5 * (jdx + numX * idx);
+            unsigned face_offset = 2 * (jdx + numX * idx);
+            face_ids[face_offset] = {edge_offset, edge_offset + 1, edge_offset + 4};
+            face_ids[face_offset + 1] = {edge_offset + 4, edge_offset + 2, edge_offset + 3};
+        }
+    }
+
+    return MeshBuilder::buildTriMesh(locations, edge_ids, face_ids);
+}