127 lines
4.1 KiB
C++
127 lines
4.1 KiB
C++
/* -*-c++-*- */
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/* osgEarth - Geospatial SDK for OpenSceneGraph
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* Copyright 2020 Pelican Mapping
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* http://osgearth.org
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*
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* osgEarth is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>
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*/
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#ifndef OSGEARTH_OVERLAY_CLAMPING_TECHNIQUE
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#define OSGEARTH_OVERLAY_CLAMPING_TECHNIQUE
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#include <osgEarth/Common>
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#include <osgEarth/OverlayDecorator>
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#include <osgEarth/Clamping>
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#define OSGEARTH_CLAMPING_BIN "osgEarth::ClampingBin"
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namespace osgEarth
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{
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class TerrainEngineNode;
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}
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namespace osgEarth { namespace Util
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{
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/**
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* Clamps geometry to the terrain using the GPU.
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*
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* This overlay technique installs a shader that samples the depth
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* of the underlying terrain and then adjusts the vertex position to
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* the height of the terrain. It then applies a depth offset in order
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* to mitigate Z-fighting.
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*
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* Approach
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*
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* This technique works by first setting up a nadir-view RTT camera that
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* captures the depth component of the terrain within the view frustum of
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* the main camera. Then the GPU uses this "depth texture" to move each
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* vertex so it coindices with the terrain.
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*
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* Limitations
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*
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* Since this is an orthographic view, the effective resolution of depth
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* data close to the camera may not be quite sufficient, especially when
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* the camera is pitched up looking out over the horizon. As a reuslt, you
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* may see the verts "jitter" slightly in the Z direciton as you camera moves.
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*
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* Performance takes a hit since we need to RTT the terrain in a pre-render
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* pass.
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*/
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class OSGEARTH_EXPORT ClampingTechnique : public OverlayTechnique
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{
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public:
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//typedef osg::Group* (*TechniqueProvider)(class MapNode*);
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//static TechniqueProvider Provider;
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public:
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ClampingTechnique();
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/**
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* The size (resolution in both directions) of the depth map texture. By
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* default, this defaults to 4096 or your hardware's maximum supported
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* texture size, whichever is less.
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*/
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void setTextureSize( int texSize );
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int getTextureSize() const { return *_textureSize; }
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public: // OverlayTechnique
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bool constrainOrthoZ() const override {
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return true;
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}
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bool hasData(
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OverlayDecorator::TechRTTParams& params) const;
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void reestablish(
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TerrainEngineNode* engine );
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void preCullTerrain(
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OverlayDecorator::TechRTTParams& params,
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osgUtil::CullVisitor* cv );
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void cullOverlayGroup(
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OverlayDecorator::TechRTTParams& params,
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osgUtil::CullVisitor* cv );
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void onInstall( TerrainEngineNode* engine );
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void onUninstall( TerrainEngineNode* engine );
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const osg::BoundingSphere& getBound(
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OverlayDecorator::TechRTTParams& params) const;
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protected:
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virtual ~ClampingTechnique() { }
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private:
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int _textureUnit;
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optional<int> _textureSize;
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TerrainEngineNode* _engine;
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mutable ClampingManager _clampingManager;
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ClampingManager& getClampingManager() { return _clampingManager; }
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friend class osgEarth::MapNode;
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private:
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void setUpCamera(OverlayDecorator::TechRTTParams& params);
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};
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} }
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#endif //OSGEARTH_OVERLAY_CLAMPING_TECHNIQUE
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