Extend set of samples (#296)

+ 12_InitFrameBuffers, 13_InitVertexBuffer, 14_InitPipeline, 15_DrawCube;
+ extend utilities and add utilities on geometries, math, and shaders
+ slightly adjust some other samples

samples/utils/math.cpp

@@ -0,0 +1,31 @@
+// Copyright(c) 2019, NVIDIA CORPORATION. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "math.hpp"
+
+namespace vk
+{
+  namespace su
+  {
+    glm::mat4x4 createModelViewProjectionClipMatrix()
+    {
+      glm::mat4x4 model = glm::mat4x4(1.0f);
+      glm::mat4x4 view = glm::lookAt(glm::vec3(-5.0f, 3.0f, -10.0f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, -1.0f, 0.0f));
+      glm::mat4x4 projection = glm::perspective(glm::radians(45.0f), 1.0f, 0.1f, 100.0f);
+      glm::mat4x4 clip = glm::mat4x4(1.0f, 0.0f, 0.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.5f, 0.0f, 0.0f, 0.0f, 0.5f, 1.0f);   // vulkan clip space has inverted y and half z !
+      return clip * projection * view * model;
+    }
+  }
+}