osgvertexprogram中的问题

bingxinguoke

osgvertexprogram中有这样一段代码。。。

1. const char vpstr[] =
   
2. "!!ARBvp1.0 # Refraction \n"
   
3. " \n"
   
4. "ATTRIB iPos = vertex.position; \n"
   
5. "#ATTRIB iCol = vertex.color.primary; \n"
   
6. "ATTRIB iNormal = vertex.normal; \n"
   
7. "PARAM esEyePos = { 0, 0, 0, 1 }; \n"
   
8. "PARAM const0123 = { 0, 1, 2, 3 }; \n"
   
9. "PARAM fresnel = program.local[0]; \n"
   
10. "PARAM refract = program.local[1]; \n"
    
11. "PARAM itMV[4] = { state.matrix.modelview.invtrans }; \n"
    
12. "PARAM MVP[4] = { state.matrix.mvp }; \n"
    
13. "PARAM MV[4] = { state.matrix.modelview }; \n"
    
14. "PARAM texmat[4] = { state.matrix.texture[0] }; \n"
    
15. "TEMP esPos; # position in eye-space \n"
    
16. "TEMP esNormal; # normal in eye-space \n"
    
17. "TEMP tmp, IdotN, K; \n"
    
18. "TEMP esE; # eye vector \n"
    
19. "TEMP esI; # incident vector (=-E) \n"
    
20. "TEMP esR; # first refract- then reflect-vector \n"
    
21. "OUTPUT oPos = result.position; \n"
    
22. "OUTPUT oColor = result.color; \n"
    
23. "OUTPUT oRefractMap = result.texcoord[0]; \n"
    
24. "OUTPUT oReflectMap = result.texcoord[1]; \n"
    
25. " \n"
    
26. "# transform vertex to clip space \n"
    
27. "DP4 oPos.x, MVP[0], iPos; \n"
    
28. "DP4 oPos.y, MVP[1], iPos; \n"
    
29. "DP4 oPos.z, MVP[2], iPos; \n"
    
30. "DP4 oPos.w, MVP[3], iPos; \n"
    
31. " \n"
    
32. "# Transform the normal to eye space. \n"
    
33. "DP3 esNormal.x, itMV[0], iNormal; \n"
    
34. "DP3 esNormal.y, itMV[1], iNormal; \n"
    
35. "DP3 esNormal.z, itMV[2], iNormal; \n"
    
36. " \n"
    
37. "# normalize normal \n"
    
38. "DP3 esNormal.w, esNormal, esNormal; \n"
    
39. "RSQ esNormal.w, esNormal.w; \n"
    
40. "MUL esNormal, esNormal, esNormal.w; \n"
    
41. " \n"
    
42. "# transform vertex position to eye space \n"
    
43. "DP4 esPos.x, MV[0], iPos; \n"
    
44. "DP4 esPos.y, MV[1], iPos; \n"
    
45. "DP4 esPos.z, MV[2], iPos; \n"
    
46. "DP4 esPos.w, MV[3], iPos; \n"
    
47. " \n"
    
48. "# vertex to eye vector \n"
    
49. "ADD esE, -esPos, esEyePos; \n"
    
50. "#MOV esE, -esPos; \n"
    
51. " \n"
    
52. "# normalize eye vector \n"
    
53. "DP3 esE.w, esE, esE; \n"
    
54. "RSQ esE.w, esE.w; \n"
    
55. "MUL esE, esE, esE.w; \n"
    
56. " \n"
    
57. "# calculate some handy values \n"
    
58. "MOV esI, -esE; \n"
    
59. "DP3 IdotN, esNormal, esI; \n"
    
60. " \n"
    
61. "# calculate refraction vector, Renderman style \n"
    
62. " \n"
    
63. "# k = 1-index*index*(1-(I dot N)^2) \n"
    
64. "MAD tmp, -IdotN, IdotN, const0123.y; \n"
    
65. "MUL tmp, tmp, refract.y; \n"
    
66. "ADD K.x, const0123.y, -tmp; \n"
    
67. " \n"
    
68. "# k<0, R = [0,0,0] \n"
    
69. "# k>=0, R = index*I-(index*(I dot N) + sqrt(k))*N \n"
    
70. "RSQ K.y, K.x; \n"
    
71. "RCP K.y, K.y; # K.y = sqrt(k) \n"
    
72. "MAD tmp.x, refract.x, IdotN, K.y; \n"
    
73. "MUL tmp, esNormal, tmp.x; \n"
    
74. "MAD esR, refract.x, esI, tmp; \n"
    
75. " \n"
    
76. "# transform refracted ray by cubemap transform \n"
    
77. "DP3 oRefractMap.x, texmat[0], esR; \n"
    
78. "DP3 oRefractMap.y, texmat[1], esR; \n"
    
79. "DP3 oRefractMap.z, texmat[2], esR; \n"
    
80. " \n"
    
81. "# calculate reflection vector \n"
    
82. "# R = 2*N*(N dot E)-E \n"
    
83. "MUL tmp, esNormal, const0123.z; \n"
    
84. "DP3 esR.w, esNormal, esE; \n"
    
85. "MAD esR, esR.w, tmp, -esE; \n"
    
86. " \n"
    
87. "# transform reflected ray by cubemap transform \n"
    
88. "DP3 oReflectMap.x, texmat[0], esR; \n"
    
89. "DP3 oReflectMap.y, texmat[1], esR; \n"
    
90. "DP3 oReflectMap.z, texmat[2], esR; \n"
    
91. " \n"
    
92. "# Fresnel approximation = fresnel*(1-(N dot I))^2 \n"
    
93. "ADD tmp.x, const0123.y, -IdotN; \n"
    
94. "MUL tmp.x, tmp.x, tmp.x; \n"
    
95. "MUL oColor, tmp.x, fresnel; \n"
    
96. " \n"
    
97. "END \n";
    
98. 
    

复制代码

这个看起来好像是汇编代码吧。。。它是什么意思啊。。
能不能不用汇编实现。。直接用openscenegraph中的函数实现。。。
初学osg。。呵呵。。还有能不能稍微介绍下这个例子。。感觉挺有趣的。。。

array

这是早期的着色语言代码，说白了就是汇编；相比之下现在的GLSL要简单许多了，您不妨直接学习后者。