Camera: Implement default camera computation

src/ViewerApplication.cpp

@@ -37,9 +37,16 @@ int ViewerApplication::run()
   const auto normalMatrixLocation =
       glGetUniformLocation(glslProgram.glId(), "uNormalMatrix");
 
+  tinygltf::Model model;
+  if (!loadGltfFile(model)) {
+    return -1;
+  }
+  glm::vec3 bboxMin, bboxMax;
+  computeSceneBounds(model, bboxMin, bboxMax);
+
   // Build projection matrix
-  auto maxDistance = 500.f; // TODO use scene bounds instead to compute this
-  maxDistance = maxDistance > 0.f ? maxDistance : 100.f;
+  const auto diag = bboxMax - bboxMin;
+  auto maxDistance = glm::length(diag);
   const auto projMatrix =
       glm::perspective(70.f, float(m_nWindowWidth) / m_nWindowHeight,
           0.001f * maxDistance, 1.5f * maxDistance);
@@ -51,14 +58,11 @@ int ViewerApplication::run()
   if (m_hasUserCamera) {
     cameraController.setCamera(m_userCamera);
   } else {
-    // TODO Use scene bounds to compute a better default camera
-    cameraController.setCamera(
-        Camera{glm::vec3(0, 0, 0), glm::vec3(0, 0, -1), glm::vec3(0, 1, 0)});
-  }
-
-  tinygltf::Model model;
-  if (!loadGltfFile(model)) {
-    return -1;
+    const auto center = 0.5f * (bboxMax + bboxMin);
+    const auto up = glm::vec3(0, 1, 0);
+    const auto eye =
+        diag.z > 0 ? center + diag : center + 2.f * glm::cross(diag, up);
+    cameraController.setCamera(Camera{eye, center, up});
   }
 
   const auto bufferObjects = createBufferObjects(model);