Graficacion Para Dummies

OpenGL

for dummies…

hello.c#include <GL/glut.h>

int main(int argc, char** argv)

{ glutInit(&argc, argv);

glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);

glutInitWindowSize (250, 250);

glutInitWindowPosition (100, 100);

glutCreateWindow ("hello");

glClearColor (0.0, 0.0, 0.0, 0.0);

glMatrixMode(GL_PROJECTION);

glLoadIdentity();

glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);}

glutDisplayFunc(display);

glutMainLoop();return 0;

}

void display(void)

{ glClear (GL_COLOR_BUFFER_BIT);

glColor3f (1.0, 1.0, 1.0);

glBegin(GL_POLYGON);

glVertex3f (0.25, 0.25, 0.0);

glVertex3f (0.75, 0.25, 0.0);

glVertex3f (0.75, 0.75, 0.0);

glVertex3f (0.25, 0.75, 0.0);

glEnd();glFlush ();

}

OpenGL’s rendering pipeline

Vertex Data

Pixel Data

EvaluatorsOperations with vertices

Assembling primitives

Operations with pixels

Fragments operations

Assembling textures

Rasterization

Frame BufferDisplay lists

cube.c

#include <GL/glut.h>

#include <stdlib.h>


{ glutInit(&argc, argv);glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);



glutCreateWindow (argv[0]);

glClearColor (0.0, 0.0, 0.0, 0.0);

glShadeModel (GL_FLAT);


glutReshapeFunc(reshape);

glutKeyboardFunc(keyboard);

glutMainLoop();

return 0;

}

cube.c

void display(void){

glClear (GL_COLOR_BUFFER_BIT);

glColor3f (1.0, 1.0, 1.0);

glLoadIdentity ();

gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0,

0.0, 0.0, 1.0, 0.0); glScalef (1.0, 2.0, 1.0);

glutWireCube (1.0);

glFlush ();

}

Viewing

transformation

Modeling

transformation

Places the camera at (0,0,5)

Aims the camera lens towards (0,0,0)

Up-vector is (0,1,0)

This defines a unique position and

orientation of the camera

cube.c#include <GL/glut.h>

#include <stdlib.h>






glClearColor (0.0, 0.0, 0.0, 0.0);





glutMainLoop();

return 0;

}

void reshape (int w, int h){

glViewport (0, 0, (GLsizei) w, (GLsizei) h);

glMatrixMode (GL_PROJECTION);

glLoadIdentity ();

glFrustum (-1.0, 1.0, -1.0, 1.0, 1.5, 20.0);

glMatrixMode (GL_MODELVIEW);

}

Projection

transformation

Defines left and right clipping planes,

Defines bottom and top clipping planes,

Defines zNear and zFar

This defines a perpective matrix

glFrustrum

How to obtain an accurate

specification of the

parameters ?

http://www.meca.ucl.ac.be/~vl/teaching/meca2170/opengl/gl/frustum.html

cube.c

void keyboard(unsigned char key, int x, int y)

{

switch (key) {

case 27: exit(0);

break; }

}

ESC allows the user to exit !


#include <stdlib.h>






glClearColor (0.0, 0.0, 0.0, 0.0);





glutMainLoop();

return 0;

}

double.c

double.c#include <GL/glut.h>#include <stdlib.h>

static GLfloat spin = 0.0;



glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);

glutInitWindowSize (250, 250); glutInitWindowPosition (100, 100);


glClearColor (0.0, 0.0, 0.0, 0.0);




glutMouseFunc(mouse);

glutMainLoop();

return 0;

}

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();

}

void reshape (int w, int h)

{ glViewport (0, 0, (GLsizei) w, (GLsizei) h);


glLoadIdentity();

glOrtho(-50.0, 50.0, -50.0, 50.0, -1.0, 1.0);

glMatrixMode(GL_MODELVIEW);

glLoadIdentity();

}

#include <GL/glut.h>#include <stdlib.h>

static GLfloat spin = 0.0;



glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);

glutInitWindowSize (250, 250); glutInitWindowPosition (100, 100);


glClearColor (0.0, 0.0, 0.0, 0.0);




glutMouseFunc(mouse);

glutMainLoop();

return 0;

}

double.c

void spinDisplay(void)

{ spin = spin + 2.0;

if (spin > 360.0)

spin = spin - 360.0;

glutPostRedisplay();

}

void mouse(int button, int state, int x, int y)

{ switch (button) {

case GLUT_LEFT_BUTTON:

if (state == GLUT_DOWN) glutIdleFunc(spinDisplay);

break;

case GLUT_MIDDLE_BUTTON:

case GLUT_RIGHT_BUTTON:

if (state == GLUT_DOWN) glutIdleFunc(NULL);

break; default:

break; }

}

bezcurve.c

bezcurve.c


#include <stdlib.h>

GLfloat ctrlpoints[4][3] = {

{ -4.0, -4.0, 0.0}, { -2.0, 4.0, 0.0},{2.0, -4.0, 0.0}, {4.0, 4.0, 0.0}};



glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);glutInitWindowSize (500, 500);



glClearColor(0.0, 0.0, 0.0, 0.0);

glShadeModel(GL_FLAT);

glMap1f(GL_MAP1_VERTEX_3, 0.0, 1.0, 3, 4,

&ctrlpoints[0][0]);

glEnable(GL_MAP1_VERTEX_3);





}

void display(void)

{ int i;

glClear(GL_COLOR_BUFFER_BIT);

glColor3f(1.0, 1.0, 1.0);glBegin(GL_LINE_STRIP); for (i =

0; i <= 30; i++)

glEvalCoord1f((GLfloat) i/30.0);

glEnd();

glPointSize(5.0);

glColor3f(1.0, 1.0, 0.0);

glBegin(GL_POINTS);

for (i = 0; i < 4; i++)

glVertex3fv(&ctrlpoints[i][0]);

glEnd();

glFlush();}


#include <stdlib.h>


{-4.0,-4.0, 0.0}, {-2.0, 4.0, 0.0},{ 2.0,-4.0, 0.0}, { 4.0, 4.0, 0.0}};



glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);glutInitWindowSize (500, 500);



glClearColor(0.0, 0.0, 0.0, 0.0);



&ctrlpoints[0][0]);






}

bezcurve.c

void reshape(int w, int h)

{ glViewport(0, 0, (GLsizei) w, (GLsizei) h);


glLoadIdentity();

if (w <= h)

glOrtho(-5.0, 5.0, 5.0*(GLfloat)h/(GLfloat)w,

5.0*(GLfloat)h/(GLfloat)w, -5.0, 5.0);

else

glOrtho(5.0*(GLfloat)w/(GLfloat)h,

5.0*(GLfloat)w/(GLfloat)h,

-5.0, 5.0,-5.0, 5.0);

glMatrixMode(GL_MODELVIEW);glLoadIdentity();

}

Et les

B-splines.


#include <stdlib.h>

GLUnurbsObj *nurb;

GLfloat knots[9] = {-3.0,-2.0,-1.0,0.0,1.0,2.0,3.0,4.0,5.0};


{-3.0,-3.0, 0.0},{-1.0, 3.0, 0.0},{ 1.0,-3.0, 0.0},

{ 3.0, 3.0, 0.0},{-3.0,-4.0, 0.0},{-2.0,-4.0, 0.0},{-1.0,-4.0, 0.0},{ 0.0,-4.0, 0.0},{ 1.0,-4.0, 0.0},

{ 2.0,-4.0, 0.0},{ 3.0,-4.0, 0.0},{ 4.0,-4.0, 0.0}};






glClearColor(0.0, 0.0, 0.0, 0.0);



&ctrlpoints[0][0]);



glutReshapeFunc(reshape);glutKeyboardFunc(keyboard);

glutMotionFunc(drag);

glutMainLoop();

return 0;

}

Nurbs = B-splines = Beziers !

Knots, pts de contrôle…void display(void)

{ glClear(GL_COLOR_BUFFER_BIT);

glColor3f(1.0, 1.0, 1.0);

glBegin(GL_LINE_STRIP);

for (i = 0; i <= 30; i++)

glEvalCoord1f((GLfloat) i/30.0);

glEnd();

glPointSize(8.0);

glBegin(GL_POINTS);

for (i = 0; i < 4; i++) {glColor3f(1.0-0.1*(double)i,1.0-0.1*(double)i,2.0*(double)i);

glVertex3fv(&ctrlpoints[i][0]); }

glEnd();

nurb = gluNewNurbsRenderer();

gluBeginCurve(nurb);

gluNurbsProperty(nurb, GLU_SAMPLING_TOLERANCE, 1.0);

gluNurbsProperty(nurb, GLU_DISPLAY_MODE, GLU_FILL);

glMaterialfv(GL_FRONT, GL_DIFFUSE, mat_red_diffuse);

gluNurbsCurve(nurb,8,knots,3,&ctrlpoints[0][0],4,GL_MAP1_VERTEX_3);

gluEndCurve(nurb);

glFlush();

}

Joindre deux Nurbs…

nurb = gluNewNurbsRenderer();gluBeginCurve(nurb);




gluNurbsCurve(nurb,8,&knots[0],3,&ctrlpoints[0][0],4,GL_MAP1_VERTEX_3);

gluEndCurve(nurb);

glColor3f(1.0,0.0,0.0);

nurb = gluNewNurbsRenderer();




gluBeginCurve(nurb);

gluNurbsCurve(nurb,8,&knots[1],3,&ctrlpoints[1][0],4,GL_MAP1_VERTEX_3);gluEndCurve(nurb);

Ce qui vous sera

demandé en 07-08

http://www.mema.ucl.ac.be/~comblen/meca2170/

Graficacion Para Dummies

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