《计算机图形学》Chapter 9 OpenGL着色语言 I-（英文）教学课件（非AI生成）.ppt

GLSLI1

ObjectivesShaderapplicationsVertexshadersFragmentshadersProgrammingshadersCgGLSL2

VertexShaderApplicationsMovingverticesMorphingWavemotionFractalsLightingMorerealisticmodelsCartoonshaders3

FragmentShaderApplicationsPerfragmentlightingcalculationspervertexlightingperfragmentlighting4

FragmentShaderApplicationsTexturemappingsmoothshadingenvironmentmappingbumpmapping5

WritingShadersFirstprogrammableshaderswereprogrammedinanassembly-likemannerOpenGLextensionsaddedforvertexandfragmentshadersCg(Cforgraphics)C-likelanguageforprogrammingshadersWorkswithbothOpenGLandDirectXInterfacetoOpenGLcomplexOpenGLShadingLanguage(GLSL)6

GLSLOpenGLShadingLanguagePartofOpenGL2.0HighlevelC-likelanguageNewdatatypesMatricesVectorsSamplersOpenGLstateavailablethroughbuilt-invariables7

SimpleVertexShaderconstvec4red=vec4(1.0,0.0,0.0,1.0);voidmain(void){gl_Position=gl_ProjectionMatrix*gl_ModelViewMartrix*gl_Vertex;gl_FrontColor=red;}8

ExecutionModel9

SimpleFragmentProgramvoidmain(void){gl_FragColor=gl_Color;}10

ExecutionModel11

DataTypesCtypes:int,float,boolVectors:floatvec2,vec3,vec4Alsoint(ivec)andboolean(bvec)Matrices:mat2,mat3,mat4StoredbycolumnsStandardreferencingm[row][column]C++styleconstructorsvec3a=vec3(1.0,2.0,3.0)vec2b=vec2(a)12

PointersTherearenopointersinGLSLWecanuseCstructswhichcanbecopiedbackfromfunctionsBecausematricesandvectorsarebasictypestheycanbepassedintoandoutputfromGLSLfunctions,e.g.matrix3func(matrix3a)13

QualifiersGLSLhasmanyofthesamequalifierssuchasconstasC/C++NeedothersduetothenatureoftheexecutionmodelVariablescanchangeOnceperprimitiveOncepervertexOnceperfragmentAtanytimeintheapplicationVertexattributesareinterpolatedbytherasterizerintofragmentattributes14

AttributeQualifierAttribute-qualifiedvariablescanchangeatmostonceper