Repo created

libs/drape/utils/projection.cpp

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+#include "drape/utils/projection.hpp"
+
+namespace dp
+{
+std::array<float, 16> MakeProjection(dp::ApiVersion apiVersion, float left, float right, float bottom, float top)
+{
+  std::array<float, 16> result = {};
+
+  // Projection matrix is calculated for [-1;1] depth-space, in some APIs (e.g. Metal)
+  // depth-space is [0;1], so we have to remap projection matrix.
+  float depthScale = 1.0f;
+  float depthOffset = 0.0f;
+  if (apiVersion == dp::ApiVersion::Metal)
+  {
+    depthScale = 0.5f;
+    depthOffset = 0.5f;
+  }
+
+  float const width = right - left;
+  float const height = top - bottom;
+  float const depth = kMaxDepth - kMinDepth;
+
+  result[0] = 2.0f / width;
+  result[3] = -(right + left) / width;
+  result[5] = 2.0f / height;
+  result[7] = -(top + bottom) / height;
+  result[10] = -2.0f * depthScale / depth;
+  result[11] = depthOffset - (kMaxDepth + kMinDepth) / depth;
+  result[15] = 1.0;
+
+  return result;
+}
+}  // namespace dp