Geometry Query Options
When SteGetGeometry() is called, it takes an SSteGeometryOptions pointer to a structure that will control what will be exported as well as how. There are numerous parameters, most of which are detailed below.
It's a good practice to use SteInitGeometryOptions() to initialize SSteGeometryOptions objects since there are no constructors in C. Its first parameter is an SSteEngine pointer. If NULL, it will use arbitrary default values. If a valid pointer is used, it will use value stored in the model file for some parameters. See the chart below.
| Member Variable | Default | Purpose |
|---|---|---|
| m_eResolution | Value saved in STE/SPM or HIGH | Every SpeedTree model in version 8 or higher has four built-in resolutions: draft, low, medium, and high. The artist is in full control of the polygon counts for each. |
| m_eGroupType | STE_GROUP_BY_GEOMETRY_TYPE | Determines how the geometry will be organized: i) grouped by like geometry type, ii) grouped by like material, or iii) hierarchy. Grouping by geometry and material results in a flat hierarchy (all data is contained in nodes directly underneath the root noode). |
| m_nHierarchy | 0 | When m_eGroupType is set to STE_GROUP_BY_HIERARCHY, m_nHierarchy sets the level in the tree under which the tree will be split apart. For example, a level of 0 means the entire mesh in one group. A level of 1 means the trunks of the tree will each be in different groups with their children (in most cases of simple trees, this will be identical to level 0 since there is only one trunk). With a level of 2, the trunk will be in one group and then each major branch will be in a group with all of its children. More explanation here, including a useful illustration. |
| m_fTimeInSecs | 0.0 | Drives both wind and growth animations. |
| m_bUseUniquePositions | false | Export position values separately from compound vertex data; keeps position values from repeating on seams. |
| m_bExportBranchSpines m_bExport3dGeometry m_bExportBones m_bExportLeafRefs m_bBranchSeamBlending | false true false false true | Engine doesn't have to export everything at once. This is good way to streamline performance when only certain components are needed. |
| m_bComputeVelocities | false | Include velocity vectors in wind computations. Off by default because it doubles the wind computation time. |
| m_bTrianglesOnly | false | Convert all quads to triangles. |
| m_bCoordsSwapYZ m_bCoordsFlipX m_bCoordsFlipY m_bCoordsFlipZ m_fCoordsScalar m_bTextureFlipV | false false false false 1.0 false | Engine is right-handed / Z-up by default. Use these flags to automatically change the output coordinates as needed. Can also scale the model, modify UV coordinates. |
| m_fSeason | Value saved in STE/SPM or 0.0 | Ranges from 0.0 to 1.0 and corresponds to the season slider in the Cinema interface. |
| m_bSeasonShowDroppedLeaves | Value saved in STE/SPM or false | Generate geometry for leaves that fall from the tree as the season changes. |
| m_bWindActive | false | When false, all expensive wind computation is bypassed. |
| m_fWindPrerollInSecs | 10.0 | Used to bypass the start-up of the wind algorithm as it reaches steady-state. |
| m_fWindStrength | 0.5 | 0.0 to 1.0 scale. 0.0 is no wind, 1.0 is full wind. Corresponds to full range of wind speed indicator in the Cinema interface. |
| m_vWindDirection | (1.0, 0.0, 0.0) | Normalized wind vector. |
| m_vWindInstancePos | (0.0, 0.0, 0.0) | Used to offset the wind noise algorithm so that the same tree model placed in two separate positions animate with different wind. |
| m_pWindInternalState | NULL | Used to support random access of wind state, often for network rendering (advanced). |
| m_bGrowthActive | true | If the loaded tree model is configured for growth, this flag will ensure that the model grows over time, driven by m_fTimeInSecs above. |