1 #include "opengl.h"

2 #include "teapot.h"

3 #include "teapot_data.h"

4

5 static void draw_patch(struct vec3 *bez_cp, int *index, int flip, int useg, int vseg, float scale);

6

7 int patch_subdivision = 6;

8

9 static int dlist_sub[32];

10

11 void bezier_teapot(float scale)

12 {

13 int i;

14

15 glMatrixMode(GL_MODELVIEW);

16

17 if(!dlist_sub[patch_subdivision]) {

18 dlist_sub[patch_subdivision] = glGenLists(1);

19 glNewList(dlist_sub[patch_subdivision], GL_COMPILE);

20

21 for(i=0; i<NUM_TEAPOT_PATCHES; i++) {

22 float flip = teapot_part_flip[i];

23 float rot = teapot_part_rot[i];

24

25 glPushMatrix();

26 glTranslatef(0, -3.15 * 0.5, 0);

27 glRotatef(rot, 0, 1, 0);

28 glScalef(1, 1, flip);

29 glRotatef(-90, 1, 0, 0);

30

31 draw_patch(teapot_verts, teapot_index + i * 16, flip < 0.0 ? 1 : 0, patch_subdivision, patch_subdivision, 1.0);

32

33 glPopMatrix();

34 }

35

36 glEndList();

37 }

38

39 scale /= 2.0;

40 glPushMatrix();

41 glScalef(scale, scale, scale);

42 glCallList(dlist_sub[patch_subdivision]);

43 glPopMatrix();

44 }

45

46 static void draw_patch(struct vec3 *bez_cp, int *index, int flip, int useg, int vseg, float scale)

47 {

48 static const float uoffs[2][4] = {{0, 0, 1, 1}, {1, 1, 0, 0}};

49 static const float voffs[4] = {0, 1, 1, 0};

50

51 int i, j, k;

52 struct vec3 cp[16];

53 struct vec3 pt, n;

54 float u, v;

55 float du = 1.0 / useg;

56 float dv = 1.0 / vseg;

57

58 /* collect control points */

59 for(i=0; i<16; i++) {

60 cp[i] = bez_cp[index[i]];

61 }

62

63 glBegin(GL_QUADS);

64 glColor3f(1, 1, 1);

65

66 u = 0;

67 for(i=0; i<useg; i++) {

68 v = 0;

69 for(j=0; j<vseg; j++) {

70

71 for(k=0; k<4; k++) {

72 pt = bezier_patch(cp, u + uoffs[flip][k] * du, v + voffs[k] * dv);

73

74 /* top/bottom normal hack */

75 if(pt.z > 3.14) {

76 n.x = n.y = 0.0f;

77 n.z = 1.0f;

78 } else if(pt.z < 0.00001) {

79 n.x = n.y = 0.0f;

80 n.z = -1.0f;

81 } else {

82 n = bezier_patch_norm(cp, u + uoffs[flip][k] * du, v + voffs[k] * dv);

83 }

84

85 glTexCoord2f(u, v);

86 glNormal3f(n.x, n.y, n.z);

87 glVertex3f(pt.x * scale, pt.y * scale, pt.z * scale);

88 }

89

90 v += dv;

91 }

92 u += du;

93 }

94

95 glEnd();

96 }