Add HandmadeMath.

Add simple morphing code.

examples/skinning/morph-targets.cc

@@ -0,0 +1,22 @@
+#include <vector>
+#include <cstdlib>
+#include <cassert>
+
+void MorthTargets(std::vector<float> &weights,
+  std::vector<std::vector<float>> &targets,
+  std::vector<float> *output)
+{
+  assert(weights.size() > 0);
+  assert(targets.size() > 0);
+  assert(weights.size() == targets.size());
+
+  // Assume all position has same number of vertices;
+
+  // TODO(parallelize)
+  for (size_t v = 0; v < targets[0].size(); v++) { // for each vertex
+    (*output)[v] = 0.0f;  
+    for (size_t i = 0; i < weights.size(); i++) {
+      (*output)[v] += weights[i] * targets[i][v];
+    }
+  }
+}

examples/skinning/premake5.lua

@@ -18,7 +18,7 @@ solution "skinning"
       kind "ConsoleApp"
       language "C++"
 	  cppdialect "C++11"
-      files { "main.cc", "skinning.cc", "../common/trackball.cc", "../common/matrix.cc" }
+      files { "main.cc", "skinning.cc", "morph-targets.cc", "../common/trackball.cc", "../common/matrix.cc" }
       includedirs { "./" }
       includedirs { "../../" }