csg.zip_OpenGL CSG_csg_csg opengl_opengl c

/* * Constructive Solid Geometry program based on information from the * Advanced OpenGL Rendering course at SIGGRAPH '96 by David Blythe and * Tom McReynolds. Click right mouse button for menu. * * author: Nate Robins * email: ndr@pobox.com * www: http://www.pobox.com/~ndr */ /* includes */ #include <GL/glut.h> #include <math.h> #include "trackball.h" /* defines */ #define SPHERE 1 #define CONE 2 #define CUBE 3 /* csgOperation * types of CSG operations */ typedef enum { CSG_A, CSG_B, CSG_A_OR_B, CSG_A_AND_B, CSG_A_SUB_B, CSG_B_SUB_A } csgOperation; /* globals */ GLint Width; GLint Height; GLfloat zoom = 0.0; GLboolean cube_picked = GL_FALSE; GLboolean sphere_picked = GL_FALSE; GLboolean cone_picked = GL_FALSE; GLboolean selection = GL_FALSE; /* rendering to selection buffer */ #define SELECT_BUFFER 32 GLuint select_buffer[SELECT_BUFFER]; /* selection buffer */ GLfloat cone_x = 0.0; GLfloat cone_y = 0.0; GLfloat cone_z = 0.0; GLfloat cube_x = 0.0; GLfloat cube_y = 0.0; GLfloat cube_z = 0.0; GLfloat sphere_x = 0.0; GLfloat sphere_y = 0.0; GLfloat sphere_z = 0.0; GLint mouse_state = -1; GLint mouse_button = -1; csgOperation Op = CSG_A_OR_B; void (*A)(void); void (*B)(void); /* functions */ /* one() * draw a single object */ void one(void(*a)(void)) { glEnable(GL_DEPTH_TEST); a(); glDisable(GL_DEPTH_TEST); } /* or() * boolean A or B (draw wherever A or B) * algorithm: simple, just draw both with depth test enabled */ void or(void(*a)(void), void(*b)()) { glPushAttrib(GL_ALL_ATTRIB_BITS); /* TODO - should just push depth */ glEnable(GL_DEPTH_TEST); a(); b(); glPopAttrib(); } /* inside() * sets stencil buffer to show the part of A * (front or back face according to 'face') * that is inside of B. */ void inside(void(*a)(void), void(*b)(void), GLenum face, GLenum test) { /* draw A into depth buffer, but not into color buffer */ glEnable(GL_DEPTH_TEST); glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glCullFace(face); a(); /* use stencil buffer to find the parts of A that are inside of B * by first incrementing the stencil buffer wherever B's front faces * are... */ glDepthMask(GL_FALSE); glEnable(GL_STENCIL_TEST); glStencilFunc(GL_ALWAYS, 0, 0); glStencilOp(GL_KEEP, GL_KEEP, GL_INCR); glCullFace(GL_BACK); b(); /* ...then decrement the stencil buffer wherever B's back faces are */ glStencilOp(GL_KEEP, GL_KEEP, GL_DECR); glCullFace(GL_FRONT); b(); /* now draw the part of A that is inside of B */ glDepthMask(GL_TRUE); glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); glStencilFunc(test, 0, 1); glDisable(GL_DEPTH_TEST); glCullFace(face); a(); /* reset stencil test */ glDisable(GL_STENCIL_TEST); } /* fixup() * fixes up the depth buffer with A's depth values */ void fixup(void(*a)(void)) { /* fix up the depth buffer */ glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glEnable(GL_DEPTH_TEST); glDisable(GL_STENCIL_TEST); glDepthFunc(GL_ALWAYS); a(); /* reset depth func */ glDepthFunc(GL_LESS); } /* and() * boolean A and B (draw wherever A intersects B) * algorithm: find where A is inside B, then find where * B is inside A */ void and(void(*a)(void), void(*b)(void)) { inside(a, b, GL_BACK, GL_NOTEQUAL); #if 1 /* set to 0 for faster, but incorrect results */ fixup(b); #endif inside(b, a, GL_BACK, GL_NOTEQUAL); } /* * sub() * boolean A subtract B (draw wherever A is and B is NOT) * algorithm: find where a is inside B, then find where * the BACK faces of B are NOT in A */ void sub(void(*a)(void), void(*b)(void)) { inside(a, b, GL_FRONT, GL_NOTEQUAL); #if 1 /* set to 0 for faster, but incorrect results */ fixup(b); #endif inside(b, a, GL_BACK, GL_EQUAL); } /* sphere() * draw a yellow sphere */ void sphere(void) { glLoadName(2); glPushMatrix(); glTranslatef(sphere_x, sphere_y, sphere_z); glColor3f(1.0, 1.0, 0.0); glutSolidSphere(5.0, 16, 16); glPopMatrix(); } /* cube() * draw a red cube */ void cube(void) { glLoadName(1); glPushMatrix(); glTranslatef(cube_x, cube_y, cube_z); glColor3f(1.0, 0.0, 0.0); glutSolidCube(8.0); glPopMatrix(); } /* cone() * draw a green cone */ void cone(void) { glLoadName(3); glPushMatrix(); glTranslatef(cone_x, cone_y, cone_z); glColor3f(0.0, 1.0, 0.0); glTranslatef(0.0, 0.0, -6.5); glutSolidCone(4.0, 15.0, 16, 16); glRotatef(180.0, 1.0, 0.0, 0.0); glutSolidCone(4.0, 0.0, 16, 1); glPopMatrix(); } void init(void) { GLfloat lightposition[] = { -3.0, 3.0, 3.0, 0.0 }; tbInit(GLUT_MIDDLE_BUTTON); glSelectBuffer(SELECT_BUFFER, select_buffer); glDepthFunc(GL_LESS); glEnable(GL_DEPTH_TEST); glEnable(GL_LIGHT0); glEnable(GL_LIGHTING); glLightfv(GL_LIGHT0, GL_POSITION, lightposition); glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE); glEnable(GL_COLOR_MATERIAL); glEnable(GL_CULL_FACE); glClearColor(0.0, 0.0, 1.0, 0.0); } void reshape(int width, int height) { Width = width; Height = height; tbReshape(width, height); glViewport(0, 0, width, height); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glFrustum(-3.0, 3.0, -3.0, 3.0, 64, 256); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -200.0 + zoom); } void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); glPushMatrix(); tbMatrix(); switch(Op) { case CSG_A: one(A); break; case CSG_B: one(B); break; case CSG_A_OR_B: or(A, B); break; case CSG_A_AND_B: and(A, B); break; case CSG_A_SUB_B: sub(A, B); break; case CSG_B_SUB_A: sub(B, A); break; } glPopMatrix(); if (!selection) glutSwapBuffers(); } GLuint pick(int x, int y) { GLuint i, hits, num_names, picked; GLuint* p; GLboolean save; GLuint depth = (GLuint)-1; GLint viewport[4]; /* get the current viewport parameters */ glGetIntegerv(GL_VIEWPORT, viewport); /* set the render mode to selection */ glRenderMode(GL_SELECT); selection = GL_TRUE; glInitNames(); glPushName(0); /* setup a picking matrix and render into selection buffer */ glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); gluPickMatrix(x, viewport[3] - y, 5.0, 5.0, viewport); glFrustum(-3.0, 3.0, -3.0, 3.0, 64, 256); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -200.0 + zoom); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); glPushMatrix(); tbMatrix(); or(A, B); glPopMatrix(); glMatrixMode(GL_PROJECTION); glPopMatrix(); glMatrixMode(GL_MODELVIEW); hits = glRenderMode(GL_RENDER); selection = GL_FALSE; p = select_buffer; picked = 0; for (i = 0; i < hits; i++) { save = GL_FALSE; num_names = *p; /* number of names in this hit */ p++; if (*p <= depth) { /* check the 1st depth value */ depth = *p; save = GL_TRUE; } p++; if (*p <= depth) { /* check the 2nd depth value */ depth = *p; save = GL_TRUE; } p++; if (save) picked = *p; p += num_names; /* skip over the rest of the names */ } return picked; } void keyboard(unsigned char key, int x, int y) { switch(key) { case 'c': if(A == cube && B == sphere) { A = sphere; B = cone; } else if(A == sphere && B == cone) { A = cone; B = cube; } else { /* if(A == cone && B = cube) */ A = cube; B = sphere; } break; case 'a': Op = CSG_A; break; case 'b': Op = CSG_B; break; case '|': Op = CSG_A_OR_B; break; case '&': Op = CSG_A_AND_B; break; case '-': Op = CSG_A_SUB_B; break;