设置纹理时，孩子结点与父亲结点关系

rubby

各位大哥：
当一个父节点（下挂多个孩子节点）的纹理设置为某张图片。
  每个孩子的纹理是这张图片的一部分还是 每个孩子的纹理就是一整张图片？

  编写了一个小程序测试，发现每个孩子的纹理就是一整张图片。
  如何使得每个孩子的纹理是这种图片的一部分。 是要设置每个孩子的纹理坐标吗？麻烦哪位大哥给点提示？ 多谢。


代码如下，运行结果见附件，图1

1. #include <osgViewer/Viewer>
   
2. #include <osgViewer/ViewerEventHandlers>
   
3. #include <osgViewer/api/win32/GraphicsWindowWin32>
   
4. #include <osgGA/TrackballManipulator>
   
5. #include <osgGA/KeySwitchMatrixManipulator>
   
6. #include <osgGA/StateSetManipulator>
   
7. #include <osgDB/DatabasePager>
   
8. #include <osgDB/Registry>
   
9. #include <osgDB/ReadFile>
   
10. #include <osgDB/WriteFile>
    
11. #include <osgUtil/Optimizer>
    
12. #include <osgUtil/SmoothingVisitor>
    
13. #include <osg/ShapeDrawable>
    
14. #include <osg/Shape>
    
15. #include <osg/MatrixTransform>
    
16. #include <osg/Transform>
    
17. #include <osg/PositionAttitudeTransform>
    
18. #include <osg/StateSet>
    
19. #include <osg/NodeVisitor>
    
20. #include <osg/ImageSequence>
    
21. #include <osg/ImageStream>
    
22. #include <osg/ClipPlane>
    
23. #include <osg/ClipNode>
    
24. #include <iostream>
    
25. #include<iomanip>
    
26. #include<fstream>
    
27. #include <vector>
    
28. #include <cstring>
    
29. #include <string>
    
30. 
    
31. 
    
32. int main(int argc, char**argv){
    
33.        
    
34.         osg::TessellationHints* hints = new osg::TessellationHints;
    
35.         hints->setDetailRatio(0.5f);
    
36.         hints->setCreateBody(true);
    
37.         //hints->setCreateBackFace(true); //必须去除这句话，否则贴图闪烁。
    
38.         hints->setCreateBottom(false);
    
39.         hints->setCreateTop(false);
    
40. 
    
41.         float radius = 5.f;
    
42.         float height = 8.f;
    
43. 
    
44.         osg::ref_ptr<osg::PositionAttitudeTransform> group = new osg::PositionAttitudeTransform;
    
45.         osg::ref_ptr<osg::Geode> genode = new osg::Geode;
    
46.         osg::ref_ptr<osg::Geode> genode2 = new osg::Geode;
    
47.         osg::ref_ptr<osg::ShapeDrawable> drawable = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,0.0f),radius,height),hints);
    
48.         osg::ref_ptr<osg::ShapeDrawable> drawable2 = new osg::ShapeDrawable(new osg::Cylinder(osg::Vec3(0.0f,0.0f,0.0f),radius,height),hints);
    
49.         genode->addDrawable(drawable.get());        // geom.get() or gemo. both are ok.
    
50.         genode2->addDrawable(drawable2.get());        // geom.get() or gemo. both are ok.
    
51. 
    
52.         osg::ref_ptr<osg::MatrixTransform> tans = new osg::MatrixTransform;
    
53.         tans->setMatrix(osg::Matrix::translate(0,0,height/2.0));
    
54.         tans->addChild(genode.get());
    
55.         osg::ref_ptr<osg::MatrixTransform> tans2 = new osg::MatrixTransform;
    
56.         tans2->setMatrix(osg::Matrix::translate(0,0,-height/2.0));
    
57.         tans2->addChild(genode2.get());
    
58.         group->addChild(tans2);
    
59.         group->addChild(tans);
    
60. 
    
61.         osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;
    
62.         osg::ref_ptr<osg::Image> image = osgDB::readImageFile("land_shallow_topo_2048.jpg");
    
63.        
    
64.         texture->setImage(image);
    
65.         texture->setFilter(osg::Texture::MIN_FILTER,osg::Texture::LINEAR);
    
66.         texture->setFilter(osg::Texture::MAG_FILTER,osg::Texture::LINEAR);       
    
67.         texture->setWrap(osg::Texture::WRAP_S,osg::Texture::CLAMP_TO_EDGE);
    
68.         texture->setWrap(osg::Texture::WRAP_T,osg::Texture::CLAMP_TO_EDGE);
    
69. 
    
70.         osg::StateSet* state = group->getOrCreateStateSet();
    
71.         state->setMode( GL_LIGHTING, osg::StateAttribute::OFF |
    
72.                 osg::StateAttribute::PROTECTED );
    
73.         state->setTextureAttributeAndModes(0,texture.get());
    
74.         osgViewer::Viewer viewer;
    
75.         viewer.setSceneData(group.get());
    
76.         viewer.addEventHandler(new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()));
    
77.         viewer.addEventHandler(new osgViewer::WindowSizeHandler);
    
78.         return viewer.run();
    
79. }

复制代码

xueyu200

我介绍一个笨办法，修改osg ShapeDrawable的代码：
1. osg::TessellationHints 中增加float _minu; float _maxu;        float _minv;float _maxv; 用于记录该Shape占用的纹理坐标
2. 修改DrawShapeVisitor中的所有gl.TexCoord2f的值 1.0修改成_max, 0.0修改成_min, 0.5修改成(_max-min)/2.0,
    const float texCoordDelta = (_maxu - _minu)/(float)numSegments;
3. 在使用时，设置osg::TessellationHints对应的uv坐标值，就ok啦
效果如下：

效果

gis_wudi

设置对应的纹理坐标比例

xueyu200

不修改osg代码的话，需要重载osg:ShapeDrawable,仅供参考

1. // Test.cpp : 定义控制台应用程序的入口点。
   
2. //
   
3. 
   
4. #include "stdafx.h"
   
5. #include <osgViewer/Viewer>
   
6. #include <osgViewer/ViewerEventHandlers>
   
7. #include <osgViewer/api/win32/GraphicsWindowWin32>
   
8. #include <osgGA/TrackballManipulator>
   
9. #include <osgGA/KeySwitchMatrixManipulator>
   
10. #include <osgGA/StateSetManipulator>
    
11. #include <osgDB/DatabasePager>
    
12. #include <osgDB/Registry>
    
13. #include <osgDB/ReadFile>
    
14. #include <osgDB/WriteFile>
    
15. #include <osgUtil/Optimizer>
    
16. #include <osgUtil/SmoothingVisitor>
    
17. #include <osg/ShapeDrawable>
    
18. #include <osg/Shape>
    
19. #include <osg/MatrixTransform>
    
20. #include <osg/Transform>
    
21. #include <osg/PositionAttitudeTransform>
    
22. #include <osg/StateSet>
    
23. #include <osg/NodeVisitor>
    
24. #include <osg/ImageSequence>
    
25. #include <osg/ImageStream>
    
26. #include <osg/ClipPlane>
    
27. #include <osg/ClipNode>
    
28. #include <iostream>
    
29. #include<iomanip>
    
30. #include<fstream>
    
31. #include <vector>
    
32. #include <cstring>
    
33. #include <string>
    
34. 
    
35. const unsigned int MIN_NUM_ROWS = 3;
    
36. const unsigned int MIN_NUM_SEGMENTS = 5;
    
37. class DrawShapeVisitor : public osg::ConstShapeVisitor
    
38. {
    
39. public:
    
40. 
    
41.         DrawShapeVisitor(osg::State& state,const osg::TessellationHints* hints, float minu = 0.0f, float maxu = 1.0f, float minv = 0.0f, float maxv = 1.0f):
    
42.           _state(state),
    
43.                   _hints(hints),
    
44.                   _minu(minu),
    
45.                   _maxu(maxu),
    
46.                   _minv(minv),
    
47.                   _maxv(maxv)
    
48.           {
    
49. #if 0
    
50.                   if (hints)
    
51.                   {
    
52.                           OSG_NOTICE<<"Warning: TessellationHints ignored in present osg::ShapeDrawable implementation."<<std::endl;
    
53.                   }
    
54. #endif
    
55.           }
    
56. 
    
57.           virtual void apply(const osg::Cylinder&);
    
58. 
    
59.           osg::State&                      _state;
    
60.           const osg::TessellationHints*    _hints;
    
61.           float _minu;
    
62.           float _maxu;
    
63.           float _minv;
    
64.           float _maxv;
    
65. 
    
66. protected:
    
67. 
    
68.         DrawShapeVisitor& operator = (const DrawShapeVisitor&) { return *this; }
    
69. 
    
70.         enum SphereHalf { SphereTopHalf, SphereBottomHalf };
    
71. 
    
72.         // helpers for apply( Cylinder | Sphere | Capsule )
    
73.         void drawCylinderBody(unsigned int numSegments, float radius, float height);
    
74. };
    
75. 
    
76. 
    
77. void DrawShapeVisitor::drawCylinderBody(unsigned int numSegments, float radius, float height)
    
78. {
    
79.         const float angleDelta = 2.0f*osg::PI/(float)numSegments;
    
80.         const float texCoordDelta = (_maxu - _minu)/(float)numSegments;
    
81. 
    
82.         const float r = radius;
    
83.         const float h = height;
    
84. 
    
85.         float basez = -h*0.5f;
    
86.         float topz = h*0.5f;
    
87. 
    
88.         float angle = 0.0f;
    
89.         float texCoord = _minu;
    
90. 
    
91.         bool drawFrontFace = _hints ? _hints->getCreateFrontFace() : true;
    
92.         bool drawBackFace = _hints ? _hints->getCreateBackFace() : false;
    
93. 
    
94.         // The only difference between the font & back face loops is that the
    
95.         //  normals are inverted and the order of the vertex pairs is reversed.
    
96.         //  The code is mostly duplicated in order to hoist the back/front face
    
97.         //  test out of the loop for efficiency
    
98. 
    
99.         osg::GLBeginEndAdapter& gl = _state.getGLBeginEndAdapter();
    
100. 
     
101.         gl.Begin(GL_QUAD_STRIP);
     
102. 
     
103.         if (drawFrontFace) {
     
104. 
     
105.                 for(unsigned int bodyi=0;
     
106.                         bodyi<numSegments;
     
107.                         ++bodyi,angle+=angleDelta,texCoord+=texCoordDelta)
     
108.                 {
     
109.                         float c = cosf(angle);
     
110.                         float s = sinf(angle);
     
111. 
     
112.                         gl.Normal3f(c,s,0.0f);
     
113. 
     
114.                         gl.TexCoord2f(texCoord,_maxv);
     
115.                         gl.Vertex3f(c*r,s*r,topz);
     
116. 
     
117.                         gl.TexCoord2f(texCoord,_minv);
     
118.                         gl.Vertex3f(c*r,s*r,basez);
     
119.                 }
     
120. 
     
121.                 // do last point by hand to ensure no round off errors.
     
122.                 gl.Normal3f(1.0f,0.0f,0.0f);
     
123. 
     
124.                 gl.TexCoord2f(_maxu,_maxv);
     
125.                 gl.Vertex3f(r,0.0f,topz);
     
126. 
     
127.                 gl.TexCoord2f(_maxu,_minv);
     
128.                 gl.Vertex3f(r,0.0f,basez);
     
129.         }
     
130. 
     
131.         if (drawBackFace) {
     
132.                 for(unsigned int bodyi=0;
     
133.                         bodyi<numSegments;
     
134.                         ++bodyi,angle+=angleDelta,texCoord+=texCoordDelta)
     
135.                 {
     
136.                         float c = cosf(angle);
     
137.                         float s = sinf(angle);
     
138. 
     
139.                         gl.Normal3f(-c,-s,0.0f);
     
140. 
     
141.                         gl.TexCoord2f(texCoord,_minv);
     
142.                         gl.Vertex3f(c*r,s*r,basez);
     
143. 
     
144.                         gl.TexCoord2f(texCoord,_maxv);
     
145.                         gl.Vertex3f(c*r,s*r,topz);
     
146.                 }
     
147. 
     
148.                 // do last point by hand to ensure no round off errors.
     
149.                 gl.Normal3f(-1.0f,0.0f,0.0f);
     
150. 
     
151.                 gl.TexCoord2f(_maxu,_minv);
     
152.                 gl.Vertex3f(r,0.0f,basez);
     
153. 
     
154.                 gl.TexCoord2f(_maxu,_maxv);
     
155.                 gl.Vertex3f(r,0.0f,topz);
     
156.         }
     
157. 
     
158.         gl.End();
     
159. }
     
160. 
     
161. void DrawShapeVisitor::apply(const osg::Cylinder& cylinder)
     
162. {
     
163.         osg::GLBeginEndAdapter& gl = _state.getGLBeginEndAdapter();
     
164. 
     
165.         gl.PushMatrix();
     
166. 
     
167.         gl.Translated(cylinder.getCenter().x(),cylinder.getCenter().y(),cylinder.getCenter().z());
     
168. 
     
169.         if (!cylinder.zeroRotation())
     
170.         {
     
171.                 osg::Matrixd rotation(cylinder.computeRotationMatrix());
     
172.                 gl.MultMatrixd(rotation.ptr());
     
173.         }
     
174. 
     
175.         // evaluate hints
     
176.         bool createBody = (_hints ? _hints->getCreateBody() : true);
     
177.         bool createTop = (_hints ? _hints->getCreateTop() : true);
     
178.         bool createBottom = (_hints ? _hints->getCreateBottom() : true);
     
179. 
     
180.         unsigned int numSegments = 40;
     
181.         float ratio = (_hints ? _hints->getDetailRatio() : 1.0f);
     
182.         if (ratio > 0.0f && ratio != 1.0f) {
     
183.                 numSegments = (unsigned int) (numSegments * ratio);
     
184.                 if (numSegments < MIN_NUM_SEGMENTS)
     
185.                         numSegments = MIN_NUM_SEGMENTS;
     
186.         }
     
187. 
     
188. 
     
189.         // cylinder body
     
190.         if (createBody)
     
191.                 drawCylinderBody(numSegments, cylinder.getRadius(), cylinder.getHeight());
     
192. 
     
193.         float angleDelta = 2.0f*osg::PI/(float)numSegments;
     
194.         float texCoordDelta = (_maxu-_minu)/(float)numSegments;
     
195.         float halfU = (_maxu-_minu)/2.0f;
     
196.         float halfV = (_maxv-_minv)/2.0f;
     
197. 
     
198.         float r = cylinder.getRadius();
     
199.         float h = cylinder.getHeight();
     
200. 
     
201.         float basez = -h*0.5f;
     
202.         float topz = h*0.5f;
     
203. 
     
204.         float angle = 0.0f;
     
205.         float texCoord = _minu;
     
206. 
     
207.         // cylinder top
     
208.         if (createTop) {
     
209.                 gl.Begin(GL_TRIANGLE_FAN);
     
210. 
     
211.                 gl.Normal3f(0.0f,0.0f,1.0f);
     
212.                 gl.TexCoord2f(0.5f,0.5f);
     
213.                 gl.Vertex3f(0.0f,0.0f,topz);
     
214. 
     
215.                 angle = 0.0f;
     
216.                 texCoord = 0.0f;
     
217.                 for(unsigned int topi=0;
     
218.                         topi<numSegments;
     
219.                         ++topi,angle+=angleDelta,texCoord+=texCoordDelta)
     
220.                 {
     
221.                         float c = cosf(angle);
     
222.                         float s = sinf(angle);
     
223. 
     
224.                         gl.TexCoord2f(c*halfU+halfU,s*halfV+halfV);
     
225.                         gl.Vertex3f(c*r,s*r,topz);
     
226.                 }
     
227. 
     
228.                 gl.TexCoord2f(_maxu,halfV);
     
229.                 gl.Vertex3f(r,0.0f,topz);
     
230. 
     
231.                 gl.End();
     
232.         }
     
233. 
     
234.         // cylinder bottom
     
235.         if (createBottom)
     
236.         {
     
237.                 gl.Begin(GL_TRIANGLE_FAN);
     
238. 
     
239.                 gl.Normal3f(0.0f,0.0f,-1.0f);
     
240.                 gl.TexCoord2f(halfU,halfV);
     
241.                 gl.Vertex3f(0.0f,0.0f,basez);
     
242. 
     
243.                 angle = osg::PI*2.0f;
     
244.                 texCoord = _maxu;
     
245.                 for(unsigned int bottomi=0;
     
246.                         bottomi<numSegments;
     
247.                         ++bottomi,angle-=angleDelta,texCoord-=texCoordDelta)
     
248.                 {
     
249.                         float c = cosf(angle);
     
250.                         float s = sinf(angle);
     
251. 
     
252.                         gl.TexCoord2f(c*halfU+halfU,s*halfV+halfV);
     
253.                         gl.Vertex3f(c*r,s*r,basez);
     
254.                 }
     
255. 
     
256.                 gl.TexCoord2f(_maxu,halfV);
     
257.                 gl.Vertex3f(r,0.0f,basez);
     
258. 
     
259.                 gl.End();
     
260.         }
     
261. 
     
262.         gl.PopMatrix();
     
263. }
     
264. 
     
265. class ShapeDrawableEx : public osg::ShapeDrawable
     
266. {
     
267. public:
     
268.         ShapeDrawableEx() : _minu(0.0f), _maxu(1.0f), _minv(0.0f), _maxv(1.0f) {}
     
269.         ShapeDrawableEx(osg::Shape* shape, osg::TessellationHints* hints=0)
     
270.                 : osg::ShapeDrawable(shape, hints), _minu(0.0f), _maxu(1.0f), _minv(0.0f), _maxv(1.0f)
     
271.         {}
     
272.         ShapeDrawableEx(const ShapeDrawableEx& pg,const osg::CopyOp& copyop=osg::CopyOp::SHALLOW_COPY)
     
273.                 : osg::ShapeDrawable(pg, copyop), _minu(pg._minu), _maxu(pg._maxu), _minv(pg._minv), _maxv(pg._maxv)
     
274.         {}
     
275. 
     
276. public:
     
277.         inline void setMinU(float v) { _minu=v; }
     
278.         inline float getMinU() const { return _minu; }
     
279.         inline void setMaxU(float v) { _maxu=v; }
     
280.         inline float getMaxU() const { return _maxu; }
     
281.         inline void setMinV(float v) { _minv=v; }
     
282.         inline float getMinV() const { return _minv; }
     
283.         inline void setMaxV(float v) { _maxv=v; }
     
284.         inline float getMaxV() const { return _maxv; }
     
285. 
     
286. public:
     
287.         virtual void drawImplementation(osg::RenderInfo& renderInfo) const
     
288.         {
     
289.                 osg::State& state = *renderInfo.getState();
     
290.                 osg::GLBeginEndAdapter& gl = state.getGLBeginEndAdapter();
     
291. 
     
292.                 if (_shape.valid())
     
293.                 {
     
294.                         gl.Color4fv(_color.ptr());
     
295. 
     
296.                         DrawShapeVisitor dsv(state,_tessellationHints.get(), _minu, _maxu, _minv, _maxv);
     
297. 
     
298.                         _shape->accept(dsv);
     
299.                 }
     
300.         }
     
301. 
     
302. protected:
     
303.         float _minu;
     
304.         float _maxu;
     
305.         float _minv;
     
306.         float _maxv;
     
307. };
     
308. 
     
309. int _tmain(int argc, _TCHAR* argv[])
     
310. {
     
311.         osg::TessellationHints* hints = new osg::TessellationHints;
     
312.         hints->setDetailRatio(0.5f);
     
313.         hints->setCreateBody(true);
     
314.         //hints->setCreateBackFace(true); //必须去除这句话，否则贴图闪烁。
     
315.         hints->setCreateBottom(false);
     
316.         hints->setCreateTop(false);
     
317.         hints->setCreateTextureCoords(true);
     
318. 
     
319.         float radius = 5.f;
     
320.         float height = 8.f;
     
321. 
     
322.         osg::ref_ptr<osg::PositionAttitudeTransform> group = new osg::PositionAttitudeTransform;
     
323.         osg::ref_ptr<osg::Geode> genode = new osg::Geode;
     
324.         osg::ref_ptr<osg::Geode> genode2 = new osg::Geode;       
     
325.         osg::ref_ptr<ShapeDrawableEx> drawable = new ShapeDrawableEx(new osg::Cylinder(osg::Vec3(0.0f,0.0f,0.0f),radius,height),hints);
     
326.         drawable->setMinV(0.5f);        // 设置纹理坐标
     
327.         osg::ref_ptr<ShapeDrawableEx> drawable2 = new ShapeDrawableEx(new osg::Cylinder(osg::Vec3(0.0f,0.0f,0.0f),radius,height),hints);
     
328.         drawable2->setMaxV(0.5f);   // 设置纹理坐标
     
329.         genode->addDrawable(drawable.get());        // geom.get() or gemo. both are ok.
     
330.         genode2->addDrawable(drawable2.get());        // geom.get() or gemo. both are ok.
     
331. 
     
332.         osg::ref_ptr<osg::MatrixTransform> tans = new osg::MatrixTransform;
     
333.         tans->setMatrix(osg::Matrix::translate(0,0,height/2.0));
     
334.         tans->addChild(genode.get());
     
335.         osg::ref_ptr<osg::MatrixTransform> tans2 = new osg::MatrixTransform;
     
336.         tans2->setMatrix(osg::Matrix::translate(0,0,-height/2.0));
     
337.         tans2->addChild(genode2.get());
     
338.         group->addChild(tans2);
     
339.         group->addChild(tans);
     
340. 
     
341.         osg::ref_ptr<osg::Texture2D> texture = new osg::Texture2D;
     
342.         osg::ref_ptr<osg::Image> image = osgDB::readImageFile("land_shallow_topo_2048.png");
     
343. 
     
344.         texture->setImage(image);
     
345.         texture->setFilter(osg::Texture::MIN_FILTER,osg::Texture::LINEAR);
     
346.         texture->setFilter(osg::Texture::MAG_FILTER,osg::Texture::LINEAR);        
     
347.         texture->setWrap(osg::Texture::WRAP_S,osg::Texture::CLAMP_TO_EDGE);
     
348.         texture->setWrap(osg::Texture::WRAP_T,osg::Texture::CLAMP_TO_EDGE);
     
349. 
     
350.         osg::StateSet* state = group->getOrCreateStateSet();
     
351.         state->setMode( GL_LIGHTING, osg::StateAttribute::OFF |
     
352.                 osg::StateAttribute::PROTECTED );
     
353.         state->setTextureAttributeAndModes(0,texture.get());
     
354.         osgViewer::Viewer viewer;
     
355.         viewer.setSceneData(group.get());
     
356.         viewer.addEventHandler(new osgGA::StateSetManipulator(viewer.getCamera()->getOrCreateStateSet()));
     
357.         viewer.addEventHandler(new osgViewer::WindowSizeHandler);
     
358.         return viewer.run();
     
359. }
     

复制代码

rubby

xueyu200 发表于 2014-6-20 10:11
不修改osg代码的话，需要重载osg:ShapeDrawable,仅供参考

特别感谢你，你大大的好啊。
还特意写了代码帮测试，thank you  so so  so much.