Viewing

1. CSC 307 1.0
Graphics Programming
Budditha Hettige
Department of Statistics and Computer Science

2. Graphics Programming
Viewing
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3. Translate
• void glTranslate{fd}(TYPE x, TYPE y, TYPE z);
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4. Rotate
void glRotate{fd}(TYPE angle, TYPE x, TYPE y, TYPE z);
glRotatef(45.0, 0.0, 0.0, 1.0) - rotation of 45 degrees
about the z-axis
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5. Scale
void glScale{fd}(TYPE x, TYPE y, TYPE z);
Example: glScalef(2.0, –0.5, 1.0)
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6. Viewing and Modeling
Transformations
• Rotating First or Translating First
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7. Viewpoint
• Object and Viewpoint at the Origin
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8. Viewpoint and the Object
• Separating the Viewpoint and the Object
• glTranslatef(0.0, 0.0, -5.0);
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9. Using the gluLookAt()
void gluLookAt
(
GLdouble eyex, GLdouble eyey, GLdouble eyez,
GLdouble centerx, GLdouble centery, GLdouble centerz,
GLdouble upx, GLdouble upy, GLdouble upz
);
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10. Default Camera Position
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gluLookAt(0.0, 0.0, 0.0, 0.0, 0.0, -100.0, 0.0, 1.0, 0.0);
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11. Using gluLookAt()
gluLookAt(4.0, 2.0, 1.0, 2.0, 4.0, -3.0, 2.0, 2.0, -1.0);
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12. Projection Transformations
• Perspective Projection
void glFrustum(GLdouble left, GLdouble right,
GLdouble bottom, GLdouble top,
GLdouble near, GLdouble far);
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13. Orthographic Projection
void glOrtho(GLdouble left, GLdouble right,
GLdouble bottom, GLdouble top,
GLdouble near, GLdouble far);
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14. Viewport Transformation
• Defining the Viewport
• void glViewport(GLint x, GLint y,
GLsizei width, GLsizei height);
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15. The Transformed Depth Coordinate
• void glDepthRange(GLclampd near,
GLclampd far);
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16. Animation
• Is an important part of computer graphics
• Taking a sequence of pictures and projecting
them at 24 frames per second on the screen
• void glutSwapBuffers(void);
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17. Example
# include <windows.h>
#include <GL/glut.h>
#include <stdlib.h>
static GLfloat spin = 0.0;
void spinDisplay(void)
{
spin = spin + 0.05;
if (spin > 360.0)
spin = spin - 360.0;
glutPostRedisplay();
}
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void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glPushMatrix();
glRotatef(spin, 0.0, 0.0, 1.0);
glColor3f(1.0, 1.0, 1.0);
glRectf(-25.0, -25.0, 25.0, 25.0);
glPopMatrix();
glutSwapBuffers();
spinDisplay();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
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18. Example
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(250, 250);
glutInitWindowPosition(100, 100);
glutCreateWindow(argv[0]);
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
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19. Building a Solar System
• planet example (planet.cpp)
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20. Building an Articulated Robot Arm
• robotArm.cpp
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