1 #version 410 compatibility

2

3 layout(quads, ccw) in;

4

5 out vec3 normal;

6 out vec3 vpos;

7 out vec2 uv;

8

9 uniform vec3 norm_scale;

10

11 vec3 bezier_patch(float u, float v);

12 vec3 bezier_patch_norm(float u, float v);

13 float bernstein(int i, float x);

14

15 void main()

16 {

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

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

19

20 uv = gl_TessCoord.xy;

21

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

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

24 }

25

26 vec3 bezier_patch(float u, float v)

27 {

28 int i, j;

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

30

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

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

33 float bu = bernstein(i, u);

34 float bv = bernstein(j, v);

35

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

37 }

38 }

39 return res;

40 }

41

42 #define DT 0.0001

43 vec3 bezier_patch_norm(float u, float v)

44 {

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

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

47 return cross(tang, bitan) * norm_scale;

48 }

49

50 float bernstein(int i, float x)

51 {

52 float invx = 1.0 - x;

53

54 if(i == 0) {

55 return invx * invx * invx;

56 }

57 if(i == 1) {

58 return 3 * x * invx * invx;

59 }

60 if(i == 2) {

61 return 3 * x * x * invx;

62 }

63 return x * x * x;

64 }