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RTC_GEOMETRY_TYPE_GRID.3embree3 - Man Page


RTC_GEOMETRY_TYPE_GRID - grid geometry type


#include <embree3/rtcore.h>

RTCGeometry geometry =
  rtcNewGeometry(device, RTC_GEOMETRY_TYPE_GRID);


Grid meshes are created by passing RTC_GEOMETRY_TYPE_GRID to the rtcNewGeometry function call, and contain an array of grid primitives. This array of grids can be specified by setting up a grid buffer (with RTC_BUFFER_TYPE_GRID type and RTC_FORMAT_GRID format) and the grid mesh vertices by setting a vertex buffer (RTC_BUFFER_TYPE_VERTEX type). See rtcSetGeometryBuffer and rtcSetSharedGeometryBuffer for more details on how to set buffers. The number of grid primitives in the grid mesh is inferred from the size of the grid buffer.

The vertex buffer contains an array of single precision x, y, z floating point coordinates (RTC_FORMAT_FLOAT3 format), and the number of vertices is inferred from the size of that buffer.

Each grid in the grid buffer is of the type RTCGrid:

struct RTCGrid
  unsigned int startVertexID;
  unsigned int stride;
  unsigned short width,height; 

The RTCGrid structure describes a 2D grid of vertices (with respect to the vertex buffer of the grid mesh). The width and height members specify the number of vertices in u and v direction, e.g. setting both width and height to 3 sets up a 3×3 vertex grid. The maximum allowed width and height is 32767. The startVertexID specifies the ID of the top-left vertex in the vertex grid, while the stride parameter specifies a stride (in number of vertices) used to step to the next row.

A vertex grid of dimensions width and height is treated as a (width-1) x (height-1) grid of quads (triangle-pairs), with the same shared edge handling as for regular quad meshes. However, the u/v coordinates have the uniform range [0..1] for an entire vertex grid. The u direction follows the width of the grid while the v direction the height.

For multi-segment motion blur, the number of time steps must be first specified using the rtcSetGeometryTimeStepCount call. Then a vertex buffer for each time step can be set using different buffer slots, and all these buffers must have the same stride and size.


On failure NULL is returned and an error code is set that can be queried using rtcGetDeviceError.




Embree Ray Tracing Kernels 3