Init
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ninja
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exchange/exchangesource/Viewer/trackball.cpp
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243
exchange/exchangesource/Viewer/trackball.cpp
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/***********************************************************************************************************************
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*
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* Copyright (c) 2010 - 2022 by Tech Soft 3D, Inc.
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* The information contained herein is confidential and proprietary to Tech Soft 3D, Inc., and considered a trade secret
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* as defined under civil and criminal statutes. Tech Soft 3D shall pursue its civil and criminal remedies in the event
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* of unauthorized use or misappropriation of its trade secrets. Use of this information by anyone other than authorized
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* employees of Tech Soft 3D, Inc. is granted only under a written non-disclosure agreement, expressly prescribing the
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* scope and manner of such use.
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*
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***********************************************************************************************************************/
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/*
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* Simple trackball-like motion adapted (ripped off) from projtex.c
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* (written by David Yu and David Blythe). See the SIGGRAPH '96
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* Advanced OpenGL course notes.
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*
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*
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* Usage:
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*
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* o call tbInit() in before any other tb call
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* o call tbReshape() from the reshape callback
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* o call tbMatrix() to get the trackball matrix rotation
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* o call tbStartMotion() to begin trackball movememt
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* o call tbStopMotion() to stop trackball movememt
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* o call tbMotion() from the motion callback
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* o call tbAnimate(GL_TRUE) if you want the trackball to continue
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* spinning after the mouse button has been released
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* o call tbAnimate(GL_FALSE) if you want the trackball to stop
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* spinning after the mouse button has been released
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*
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* Typical setup:
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*
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*
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void
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init(void)
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{
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tbInit(GLUT_MIDDLE_BUTTON);
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tbAnimate(GL_TRUE);
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. . .
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}
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void
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reshape(int width, int height)
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{
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tbReshape(width, height);
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. . .
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}
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void
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display(void)
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{
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glPushMatrix();
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tbMatrix();
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. . . draw the scene . . .
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glPopMatrix();
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}
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void
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mouse(int button, int state, int x, int y)
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{
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tbMouse(button, state, x, y);
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. . .
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}
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void
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motion(int x, int y)
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{
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tbMotion(x, y);
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. . .
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}
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int
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main(int argc, char** argv)
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{
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. . .
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init();
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glutReshapeFunc(reshape);
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glutDisplayFunc(display);
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glutMouseFunc(mouse);
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glutMotionFunc(motion);
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. . .
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}
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*
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* */
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/* includes */
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#include <math.h>
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#include <assert.h>
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#ifdef __APPLE__
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#include <GLUT/glut.h>
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#else
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#include <GL/glut.h>
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#endif
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#include "trackball.h"
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/* globals */
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static GLuint tb_lasttime;
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static GLfloat tb_lastposition[3];
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static GLfloat tb_angle = 0.0;
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static GLfloat tb_axis[3];
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static GLfloat tb_transform[4][4];
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static GLuint tb_width;
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static GLuint tb_height;
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static GLint tb_button = -1;
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static GLboolean tb_tracking = GL_FALSE;
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static GLboolean tb_animate = GL_TRUE;
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/* functions */
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static void _tbPointToVector(int x, int y, int width, int height, float v[3])
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{
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float d, a;
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/* project x, y onto a hemi-sphere centered within width, height. */
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v[0] = (2.0 * x - width) / width;
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v[1] = (height - 2.0 * y) / height;
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d = sqrt(v[0] * v[0] + v[1] * v[1]);
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v[2] = cos((3.14159265 / 2.0) * ((d < 1.0) ? d : 1.0));
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a = 1.0 / sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
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v[0] *= a;
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v[1] *= a;
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v[2] *= a;
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}
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static void _tbAnimate(void)
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{
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glutPostRedisplay();
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}
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void _tbStartMotion(int x, int y, int /*button*/, int time)
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{
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assert(tb_button != -1);
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tb_tracking = GL_TRUE;
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tb_lasttime = time;
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_tbPointToVector(x, y, tb_width, tb_height, tb_lastposition);
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}
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void _tbStopMotion(int /*button*/, unsigned time)
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{
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assert(tb_button != -1);
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tb_tracking = GL_FALSE;
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if(time == tb_lasttime && tb_animate) {
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glutIdleFunc(_tbAnimate);
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} else {
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tb_angle = 0.0;
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if(tb_animate)
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glutIdleFunc(0);
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}
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}
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void tbAnimate(GLboolean animate)
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{
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tb_animate = animate;
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}
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void tbInit(GLuint button)
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{
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tb_button = button;
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tb_angle = 0.0;
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/* put the identity in the trackball transform */
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glPushMatrix();
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glLoadIdentity();
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glGetFloatv(GL_MODELVIEW_MATRIX, (GLfloat *)tb_transform);
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glPopMatrix();
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}
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void tbMatrix()
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{
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assert(tb_button != -1);
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glPushMatrix();
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glLoadIdentity();
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glRotatef(tb_angle, tb_axis[0], tb_axis[1], tb_axis[2]);
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glMultMatrixf((GLfloat *)tb_transform);
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glGetFloatv(GL_MODELVIEW_MATRIX, (GLfloat *)tb_transform);
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glPopMatrix();
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glMultMatrixf((GLfloat *)tb_transform);
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}
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void tbReshape(int width, int height)
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{
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assert(tb_button != -1);
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tb_width = width;
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tb_height = height;
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}
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void tbMouse(int button, int state, int x, int y)
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{
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assert(tb_button != -1);
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if(state == GLUT_DOWN && button == tb_button)
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_tbStartMotion(x, y, button, glutGet(GLUT_ELAPSED_TIME));
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else if(state == GLUT_UP && button == tb_button)
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_tbStopMotion(button, glutGet(GLUT_ELAPSED_TIME));
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}
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void tbMotion(int x, int y)
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{
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GLfloat current_position[3], dx, dy, dz;
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assert(tb_button != -1);
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if(tb_tracking == GL_FALSE)
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return;
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_tbPointToVector(x, y, tb_width, tb_height, current_position);
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/* calculate the angle to rotate by (directly proportional to the
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length of the mouse movement */
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dx = current_position[0] - tb_lastposition[0];
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dy = current_position[1] - tb_lastposition[1];
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dz = current_position[2] - tb_lastposition[2];
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tb_angle = 90.0 * sqrt(dx * dx + dy * dy + dz * dz);
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/* calculate the axis of rotation (cross product) */
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tb_axis[0] = tb_lastposition[1] * current_position[2] -
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tb_lastposition[2] * current_position[1];
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tb_axis[1] = tb_lastposition[2] * current_position[0] -
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tb_lastposition[0] * current_position[2];
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tb_axis[2] = tb_lastposition[0] * current_position[1] -
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tb_lastposition[1] * current_position[0];
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/* reset for next time */
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tb_lasttime = glutGet(GLUT_ELAPSED_TIME);
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tb_lastposition[0] = current_position[0];
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tb_lastposition[1] = current_position[1];
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tb_lastposition[2] = current_position[2];
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/* remember to draw new position */
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glutPostRedisplay();
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}
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