Licht. Elektromagnetische Strahlung Emitter > Reflektor -> Auge. Sichtbares Spektrum: 400nm 700nm. Universität Frankfurt

Transkript

1 Licht Elektromagnetische Strahlung Emitter > Reflektor -> Auge Sichtbares Spektrum: 400nm 700nm

2 Farbwahrnehmung Farbbeschreibung I Farbton - rot, gelb, blau,... Helligkeit Nähe zu schwarz oder weiss Sättigung Abweichung vom grau der gleichen Helligkeit

3 Farbwahrnehmung Farbbeschreibung II

4 Farbwiedergabe

5 Farbdefinition I RGB-Modell

6 Farbdefinition in OpenGL void glcolor3{b s i f d ub us ui} (TYPE r, TYPE g, TYPE b); void glcolor3{b s i f d ub us ui}v (const TYPE *v); Beispiel: glcolor3f(1.0, 0, 0) //rot glvertex3f (0,0,0); glcolor3ub (0, 255, 255) // türkis...

7 Shading I Gouraud Shading

8 Shading II void glshademodel (GLenum mode) mode: GL_FLAT, GL_SMOOTH

9 Shading III glshademodel (GL_FLAT); glbegin(gl_triangles); glcolor3f(0,0,1); glvertex3f(0.0f, 0.5f, 0.0f); // Blue top glcolor3f(0, 1, 0); glvertex3f(-1.0f, -0.5f, 0.0f); // Green left bottom corner glcolor3f(1,0,0); glvertex3f(1.0f, -0.5f, 0.0f); // Red Bottom Right glend(); glshademodel (GL_SMOOTH); glbegin(gl_triangles); glcolor3f(0,0,1); glvertex3f(0.0f, 0.5f, 0.0f); // Blue top glcolor3f(0, 1, 0); glvertex3f(-1.0f, -0.5f, 0.0f); // Green left bottom corner glcolor3f(1,0,0); glvertex3f(1.0f, -0.5f, 0.0f); // Red Bottom Right glend();

10 Diffuse Reflexion I

11 Diffuse Reflexion II I D = ( IL kd)*max( L,0) D

12 void draw_sphere (float r, int segb, int segl) { GLint i, j; GLfloat x,y,z; GLfloat sin_j //Part of sphere built of quadstrips for (j=1; j<segb-1; j++) { glbegin(gl_quad_strip); x = r*sin(j*pi/segb); y = r*cos(j*pi/segb); z = 0.0; glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); Normale I Kugel x = r*sin((j+1)*pi/segb); y = r*cos((j+1)*pi/segb); z = 0.0; glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z);

13 Normale II for (i=1; i<segl; i++) { sin_j = r*sin(j*pi/segb); x = sin_j*cos(i*pi2/segl); y = r*cos(j*pi/segb); z = -1.0*sin_j*sin(i*PI2/segL); glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); sin_j = r*sin((j+1)*pi/segb); x = sin_j*cos(i*pi2/segl); y = r*cos((j+1)*pi/segb); z = -1.0*sin_j*sin(i*PI2/segL); glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); } //end of "for i"

14 Normale III x = r*sin(j*pi/segb); y = r*cos(j*pi/segb); z = 0.0; glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); x = r*sin((j+1)*pi/segb); y = r*cos((j+1)*pi/segb); z = 0.0; glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); glend(); } //end of "for j"

15 Normale VI glbegin(gl_triangle_fan); //Now the northern pole cap glnormal3f (0, 1.0, 0); glvertex3f (0.0, r, 0.0); // North Pole for (i=0; i<segl+1; i++) { sin_j = r*sin(pi/segb); x = sin_j*cos(i*pi2/segl); y = r*cos(pi/segb); z = -1.0*sin_j*sin(i*PI2/segL); glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); } glend();

16 Normale V glbegin(gl_triangle_fan); // Now the southern pole cap glnormal3f (0, -1.0, 0); glvertex3f (0.0, -1.0*r, 0.0); // South Pole for (i=0; i>-1*(segl+1); i--) { sin_j = r*sin((segb-1)*pi/segb); x = sin_j*cos(i*pi2/segl); y = r*cos((segb-1)*pi/segb); z = -1.0*sin_j*sin(i*PI2/segL); glnormal3f (x/r, y/r, z/r); glvertex3f (x, y, z); } glend(); }

17 Normale VI Wie erhalte ich Einheitsvektoren? 1. Generiere Einheitsvektoren und verwende nur Rotation und Translation (keine Skalierung) als Transformation. 2. Verwende glenable(gl_normalize). Performance-Einbuße! 3. glenable(gl_rescale_normal); //OpenGL 1.2

18 Diffuse Beleuchtung I void gllight{i,f}(glenum light, GLenum pname, TYPE param) void gllight{i,f}v(glenum light, GLenum pname, TYPE *param) light: GL_LIGHT0,, GL_LIGHT7 pname: GL_DIFFUSE, GL_POSITION param: z.b. (1.0, 1.0, 1.0, 1.0) void glmaterial{i,f}(glenum face, GLenum pname, TYPE param) void glmaterial{i,f}v(glenum face, GLenum pname, TYPE *param) face: GLFRONT, GL_BACK, GL_FRONT_AND_BACK pname: GL_DIFFUSE param: z.b. (1.0, 0.0, 0.0,1.0)

19 Diffuse Beleuchtung II void init(void) { GLfloat light_position[] = { 1.0, 1.0, 1.0, 1.0 }; //Lichtquelle bei (1, 1, 1) //GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 }; //Lichtquelle im Unendlichen gllightfv(gl_light0, GL_POSITION, light_position); GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; gllightfv(gl_light0, GL_DIFFUSE, light_diffuse); GLfloat mat_diffuse[] = { 0.8, 0.0, 0.8, 1.0 }; glmaterialfv(gl_front, GL_DIFFUSE, mat_diffuse); glenable(gl_lighting); glenable(gl_light0); } glenable(gl_depth_test); glenable(gl_cull_face); glshademodel (GL_SMOOTH); glclearcolor (0.5, 0.5, 0.5, 0.0);

20 Diffuse Beleuchtung III

21 Ambiente Beleuchtung I I = I D + I A I A = I L A* k A

22 Ambiente Beleuchtung II void init(void) { GLfloat light_position[] = { 1.0, 1.0, 1.0, 1.0 }; //Lichtquelle in (1, 1, 1) //GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 }; //Lichtquelle im Unendlichen gllightfv(gl_light0, GL_POSITION, light_position); GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; gllightfv(gl_light0, GL_DIFFUSE, light_diffuse); GLfloat light_ambient[] = { 0.2, 0.2, 0.2, 1.0 }; gllightfv(gl_light0, GL_AMBIENT, light_ambient); GLfloat mat_diffuse[] = { 0.8, 0.0, 0.8, 1.0 }; glmaterialfv(gl_front, GL_DIFFUSE, mat_diffuse); glmaterialfv(gl_front, GL_AMBIENT, mat_diffuse); } glenable(gl_lighting); glenable(gl_light0); glenable(gl_depth_test); glenable(gl_cull_face); glshademodel (GL_SMOOTH); glclearcolor (0.5, 0.5, 0.5, 0.0);

23 Phong: I Beleuchtung/Highlights I n = I L ks R V s s * OpenGL: I n = I L ks H N s s * / mit H = L+ V 2

24 Beleuchtung/Highlights II GLfloat mat_diffuse[] = { 0.8, 0.0, 0.8, 1.0 }; GLfloat mat_specular[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat mat_shininess[] = { 50.0 }; GLfloat light_position[] = { 1.0, 1.0, 1.0, 0.0 }; GLfloat light_ambient[] = { 0.2, 0.2, 0.2, 1.0 }; GLfloat light_diffuse[] = { 1.0, 1.0, 1.0, 1.0 }; GLfloat light_specular[] = { 1.0, 1.0, 1.0, 1.0 }; glmaterialfv(gl_front, GL_DIFFUSE, mat_diffuse); glmaterialfv(gl_front, GL_AMBIENT, mat_diffuse); glmaterialfv(gl_front, GL_SPECULAR, mat_specular); glmaterialfv(gl_front, GL_SHININESS, mat_shininess); gllightfv(gl_light0, GL_POSITION, gllightfv(gl_light0, GL_DIFFUSE, gllightfv(gl_light0, GL_AMBIENT, gllightfv(gl_light0, GL_SPECULAR, light_position); light_diffuse); light_ambient); light_specular);

25 Beleuchtung/Highlights III I = IA + ID + I S

26 Globale Beleuchtungsparameter void gllightmodel{i,f}(glenum pname, TYPE param) void gllightmodel{i,f}v(glenum pname,type *param) Parameter-Name Default-Wert GL_LIGHT_MODEL_AMBIENT (0.2, 0.2, 0.2, 1.0) GL_LIGHT_MODEL_LOCAL_VIEWER 0.0, GL_FALSE GL_LIGHT_MODEL_TWO_SIDE 0.0, GL_FALSE GL_LIGHT_MODEL_COLOR_CONTROL GL_SINGLE_COLOR

27 Spot Lights I void gllight{i,f}(glenum light, GLenum pname, TYPE param) pname: GL_SPOT_DIRECTION, GL_SPOT_EXPONENT, GL_SPOT_CUTOFF

28 Spot Lights II 2º 10 º 45 º Öffnungswinkel

29 Spot Lights III Exponent 45 º Öffnungswinkel

30 Dämpfung I L = I L d) = I ( L max k c + k l * 1 d + k q * d 2 Beispiel: gllightf(gl_light0, GL_CONSTANT_ATTENUATION, 2.0) gllightf(gl_light0, GL_LINEAR_ATTENUATION, 2.0) gllightf(gl_light0, GL_QUADRATIC_ATTENUATION, 2.0)

31 Lichtquellen in OpenGL Parameter Name GL_AMBIENT GL_DIFFUSE GL_SPECULAR GL_POSITION GL_SPOT_DIRECTION GL_SPOT_EXPONENT GL_SPOT_CUTOFF GL_CONSTANT_ATTENUATION GL_LINEAR_ATTENUATION GL_QUADRATIC_ATTENUATION Default Value (0.0, 0.0, 0.0, 1.0) (1.0, 1.0, 1.0, 1.0) (1.0, 1.0, 1.0, 1.0) (0.0, 0.0, 1.0, 0.0) (0.0, 0.0, -1.0) Meaning ambient RGBA intensity of light diffuse RGBA intensity of light specular RGBA intensity of light (x, y, z, w) position of light (x, y, z) direction of spotlight spotlight exponent spotlight cutoff angle constant attenuation factor linear attenuation factor quadratic attenuation factor

32 Materialeigenschaften in OpenGL Parameter Name Default Value Meaning GL_AMBIENT GL_DIFFUSE GL_AMBIENT_AND_DIFFUSE GL_SPECULAR GL_SHININESS GL_EMISSION (0.2, 0.2, 0.2, 1.0) (0.8, 0.8, 0.8, 1.0) (0.0, 0.0, 0.0, 1.0) 0.0 (0.0, 0.0, 0.0, 1.0) ambient color of material diffuse color of material ambient and diffuse color of material specular color of material specular exponent emissive color of material

33 void display(void) { Lichtquellen in der Szene I Statische Lichtquelle GLfloat light_position[] = { 0.0, 1.0, 3.0, 1.0 }; glclear (GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT); glloadidentity (); /* clear the modeling matrix */ /* viewing transformation */ glulookat (vx, 3.0, vz, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); gllightfv (GL_LIGHT0, GL_POSITION, light_position); glrotatef(75.0, 1.0, 0, 0); /* modeling transformation */ draw_torus(1.0, 0.5, 128, 256); glutswapbuffers(); }

34 Lichtquellen in der Szene II Bewegte Lichtquelle void display(void) { GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 }; glclear (GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT); glpushmatrix (); glulookat (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); glpushmatrix (); glrotated ((GLdouble) spin, 1.0, 0.0, 0.0); gltranslated (0.0, 0.0, 1.5); gllightfv (GL_LIGHT0, GL_POSITION, position);

35 Lichtquellen in der Szene IIa Bewegte Lichtquelle gldisable (GL_LIGHTING); glcolor3f (0.0, 1.0, 1.0); glutwirecube (0.1); glenable (GL_LIGHTING); glpopmatrix (); glutsolidtorus (0.275, 0.85, 16, 32); glpopmatrix (); glflush (); }

36 void display(void) { GLfloat position[] = {0, 0, 0, 1}; Lichtquellen in der Szene III Headlight glclear (GL_COLOR_BUFFER_BIT GL_DEPTH_BUFFER_BIT); glcolor3f (1.0, 0.5, 1.0); glloadidentity (); /* clear the modeling matrix */ gllightfv (GL_LIGHT0, GL_POSITION, position); /* light source in eye point */ glulookat (vx, 3.0, vz, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); /* viewing transformation */ glrotatef(75.0, 1.0, 0, 0); /* modeling transformation */ draw_torus(1.0, 0.5, 128, 256); } glutswapbuffers();