1 #version 410 compatibility

2

3 layout(quads, ccw) in;

4

5 out vec3 normal;

6 out vec3 vpos;

7

8 uniform vec3 norm_scale;

9

10 vec3 bezier_patch(float u, float v);

11 vec3 bezier_patch_norm(float u, float v);

12 float bernstein(int i, float x);

13

14 void main()

15 {

16 vec3 pos = bezier_patch(gl_TessCoord.x, gl_TessCoord.y);

17 normal = gl_NormalMatrix * bezier_patch_norm(gl_TessCoord.x, gl_TessCoord.y);

18

19 gl_Position = gl_ModelViewProjectionMatrix * vec4(pos, 1.0);

20 vpos = (gl_ModelViewMatrix * vec4(pos, 1.0)).xyz;

21 }

22

23 vec3 bezier_patch(float u, float v)

24 {

25 int i, j;

26 vec3 res = vec3(0.0, 0.0, 0.0);

27

28 for(j=0; j<4; j++) {

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

30 float bu = bernstein(i, u);

31 float bv = bernstein(j, v);

32

33 res += gl_in[j * 4 + i].gl_Position.xyz * bu * bv;

34 }

35 }

36 return res;

37 }

38

39 #define DT 0.0001

40 vec3 bezier_patch_norm(float u, float v)

41 {

42 vec3 tang = bezier_patch(u + DT, v) - bezier_patch(u - DT, v);

43 vec3 bitan = bezier_patch(u, v + DT) - bezier_patch(u, v - DT);

44 return cross(tang, bitan) * norm_scale;

45 }

46

47 float bernstein(int i, float x)

48 {

49 float invx = 1.0 - x;

50

51 if(i == 0) {

52 return invx * invx * invx;

53 }

54 if(i == 1) {

55 return 3 * x * invx * invx;

56 }

57 if(i == 2) {

58 return 3 * x * x * invx;

59 }

60 return x * x * x;

61 }