GetArea
For perfomance reasons it is benefitial to call it with vertex and index array when
the arrays are calculated anyway or Volume and Area are needed.
There are two ways to call GetVolume:
vertices and indices are both zero: in this case the instance will be
recalculated when needed. It is expected the client does not
need the arrays itself or there is no performance issue.
vertices and indices are both given: the call is placed directly after
updateBuffer calls and no structural change to depending instances have
been done in between. The transformationMatrix array is not needed,
even if it is being used due to not giving any performance gain to this
operation.
Note: internally the call does not store its results, any optimization based on known
dependancies between instances need to be implemented on the client.
Note: in case precision is important and vertex array is 32 bit it is advised to
set vertices and indices to 0 even if arrays are existing.
Syntax
// Visual Studio for Windows public: double __declspec(dllexport) __stdcall GetArea( __int64 owlInstance, const void * vertices, const void * indices ); // Linux, OS-X and non-Visual Studio Windows solutions public: double GetArea( int64_t owlInstance, const void * vertices, const void * indices );
Property owlInstance
Size: 64 bit / 8 byte (value)Property vertices
Size: 32 bit / 4 byte (reference)Property indices
Size: 32 bit / 4 byte (reference)
Example
Here you can find code snippits that show how the API call GetArea can be used.
#include "engine/include/engine.h" #include <assert.h>void main() { int64_t model = CreateModel(); if (model) { // // Classes // int64_t classBox = GetClassByName(model, "Box"); // // Datatype Properties (attributes) // int64_t propertyLength = GetPropertyByName(model, "length"), propertyWidth = GetPropertyByName(model, "width"), propertyHeight = GetPropertyByName(model, "height"); // // Instances (creating) // int64_t instanceBox = CreateInstance(classBox, nullptr); double length = 2.8, width = 1.3, height = 1.4; SetDatatypeProperty(instanceBox, propertyLength, &length, 1); SetDatatypeProperty(instanceBox, propertyWidth, &width, 1); SetDatatypeProperty(instanceBox, propertyHeight, &height, 1); // // Simple use of the derived information functions // double volume = GetVolume(instanceBox, nullptr, nullptr), area = GetArea(instanceBox, nullptr, nullptr), perimeter = GetPerimeter(instanceBox); int64_t vertexBufferSize = 0, indexBufferSize = 0; CalculateInstance(instanceBox, &vertexBufferSize, &indexBufferSize, 0); if (vertexBufferSize && indexBufferSize) { float * vertexBuffer = new float[6 * vertexBufferSize]; UpdateInstanceVertexBuffer(instanceBox, vertexBuffer); int32_t * indexBuffer = new int32_t[indexBufferSize]; UpdateInstanceIndexBuffer(instanceBox, indexBuffer); // // Reuse knowledge to improve performance (in case of single precision, with less accuracy) // volume = GetVolume(instanceBox, vertexBuffer, indexBuffer); area = GetArea(instanceBox, vertexBuffer, indexBuffer); } // // The resulting model can be viewed in 3D-Editor.exe // SaveModel(model, "c:\\created\\myFile.bin"); CloseModel(model); } }