tessellation_src_main.rar_Tessellation_凹多边形_凹多边形 opengl

/////////////////////////////////////////////////////////////////////////////// // main.cpp // ======== // Example of OpenGL Tessellation // Tessellation is used for subdividing concave planar polygons or polygons // with intersecting edges into convex polygons. In this example, there are 3 // different types of models; // 1) tessellate1(): a concave quad // 2) tessellate2(): a quad with hole in it // 3) tessellate3(): a star shape (5 vertices) with intersecting edges // // By using OpenGL tessellation operation, these 3 models will be converted // into convex polygons. Note that all vertices of a polygon are lying on a // same plane // In this example, the actual OpenGL calls are recorded and printed out to // console. Examine the output to see what tessellator does for you. // // AUTHOR: Song Ho Ahn (song.ahn@gmail.com) // CREATED: 2003-05-06 // UPDATED: 2006-02-22 /////////////////////////////////////////////////////////////////////////////// #include <GL/glut.h> #include <iostream> #include <sstream> #include <iomanip> using std::stringstream; using std::cout; using std::cerr; using std::endl; using std::ends; #ifndef CALLBACK #define CALLBACK #endif // CALLBACK functions for GLU_TESS //////////////////////////////////////////// // NOTE: must be declared with CALLBACK directive void CALLBACK tessBeginCB(GLenum which); void CALLBACK tessEndCB(); void CALLBACK tessErrorCB(GLenum errorCode); void CALLBACK tessVertexCB(const GLvoid *data); void CALLBACK tessVertexCB2(const GLvoid *data); void CALLBACK tessCombineCB(const GLdouble newVertex[3], const GLdouble *neighborVertex[4], const GLfloat neighborWeight[4], GLdouble **outData); // GLUT CALLBACK functions //////////////////////////////////////////////////// void displayCB(); void reshapeCB(int w, int h); void timerCB(int millisec); void idleCB(); void keyboardCB(unsigned char key, int x, int y); void mouseCB(int button, int stat, int x, int y); void mouseMotionCB(int x, int y); // function declarations ////////////////////////////////////////////////////// void initGL(); int initGLUT(int argc, char **argv); bool initSharedMem(); void clearSharedMem(); void initLights(); void setCamera(float posX, float posY, float posZ, float targetX, float targetY, float targetZ); void drawString(const char *str, int x, int y, float color[4], void *font); void drawString3D(const char *str, float pos[3], float color[4], void *font); void showInfo(); const char* getPrimitiveType(GLenum type); GLuint tessellate1(); GLuint tessellate2(); GLuint tessellate3(); // global variables /////////////////////////////////////////////////////////// void *font = GLUT_BITMAP_8_BY_13; bool mouseLeftDown; bool mouseRightDown; float mouseX, mouseY; float cameraAngleX; float cameraAngleY; float cameraDistance; int drawMode = 0; GLuint listId1, listId2, listId3; // IDs of display lists GLdouble vertices[64][6]; // arrary to store newly created vertices (x,y,z,r,g,b) by combine callback int vertexIndex = 0; // array index for above array incremented inside combine callback // DEBUG // stringstream ss; /////////////////////////////////////////////////////////////////////////////// int main(int argc, char **argv) { initSharedMem(); // init GLUT and GL initGLUT(argc, argv); initGL(); // perform tessellation and compile into display lists listId1 = tessellate1(); // a concave quad listId2 = tessellate2(); // a quad with a hole in it listId3 = tessellate3(); // a self-intersecting star // the last GLUT call (LOOP) // window will be shown and display callback is triggered by events // NOTE: this call never return main(). glutMainLoop(); /* Start GLUT event-processing loop */ return 0; } /////////////////////////////////////////////////////////////////////////////// // create a tessellation object and compile a quad into a display list /////////////////////////////////////////////////////////////////////////////// GLuint tessellate1() { GLuint id = glGenLists(1); // create a display list if(!id) return id; // failed to create a list, return 0 GLUtesselator *tess = gluNewTess(); // create a tessellator if(!tess) return 0; // failed to create tessellation object, return 0 // define concave quad data (vertices only) // 0 2 // \ \/ / // \3 / // \/ // 1 GLdouble quad1[4][3] = { {-1,3,0}, {0,0,0}, {1,3,0}, {0,2,0} }; // register callback functions gluTessCallback(tess, GLU_TESS_BEGIN, (void (CALLBACK *)())tessBeginCB); gluTessCallback(tess, GLU_TESS_END, (void (CALLBACK *)())tessEndCB); gluTessCallback(tess, GLU_TESS_ERROR, (void (CALLBACK *)())tessErrorCB); gluTessCallback(tess, GLU_TESS_VERTEX, (void (CALLBACK *)())tessVertexCB); // tessellate and compile a concave quad into display list // gluTessVertex() takes 3 params: tess object, pointer to vertex coords, // and pointer to vertex data to be passed to vertex callback. // The second param is used only to perform tessellation, and the third // param is the actual vertex data to draw. It is usually same as the second // param, but It can be more than vertex coord, for example, color, normal // and UV coords which are needed for actual drawing. // Here, we are looking at only vertex coods, so the 2nd and 3rd params are // pointing same address. glNewList(id, GL_COMPILE); //glColor3f(1,1,1); gluTessBeginPolygon(tess, 0); // with NULL data gluTessBeginContour(tess); gluTessVertex(tess, quad1[0], quad1[0]); gluTessVertex(tess, quad1[1], quad1[1]); gluTessVertex(tess, quad1[2], quad1[2]); gluTessVertex(tess, quad1[3], quad1[3]); gluTessEndContour(tess); gluTessEndPolygon(tess); glEndList(); gluDeleteTess(tess); // delete after tessellation // DEBUG // // print out actual GL calls that are performed cout << endl; cout << "1. Concave Quad\n"; cout << "===============\n"; cout << ss.str().c_str() << endl; ss.str(""); // clear string buffer return id; // return handle ID of a display list } /////////////////////////////////////////////////////////////////////////////// // tessellate a polygon with a hole and compile it into a display list /////////////////////////////////////////////////////////////////////////////// GLuint tessellate2() { GLuint id = glGenLists(1); // create a display list if(!id) return id; // failed to create a list, return 0 GLUtesselator *tess = gluNewTess(); // create a tessellator if(!tess) return 0; // failed to create tessellation object, return 0 // define concave quad with a hole // 0--------3 // | 4----7 | // | | | | // | 5----6 | // 1--------2 GLdouble quad2[8][3] = { {-2,3,0}, {-2,0,0}, {2,0,0}, { 2,3,0}, {-1,2,0}, {-1,1,0}, {1,1,0}, { 1,2,0} }; // register callback functions gluTessCallback(tess, GLU_TESS_BEGIN, (void (__stdcall*)(void))tessBeginCB); gluTessCallback(tess, GLU_TESS_END, (void (__stdcall*)(void))tessEndCB); gluTessCallback(tess, GLU_TESS_ERROR, (void (__stdcall*)(void))tessErrorCB); gluTessCallback(tess, GLU_TESS_VERTEX, (void (__stdcall*)())tessVertexCB); // tessellate and compile a concave quad into display list glNewList(id, GL_COMPILE); glColor3f(1,1,1); gluTessBeginPolygon(tess, 0); // with NULL data gluTessBeginContour(tess); // outer quad gluTessVertex(tess, quad2[0], quad2[0]);