Shadow Mapping - OpenGL ES SDK for Android - GitHub Pages

Shadow Mapping. Yellow cube represents the spot light source. The application displays two cubes on a plane which are lit by directional and spot lights. The ... OpenGLESSDKforAndroid ARMDeveloperCenter Home Pages Namespaces Files  All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Friends Macros Pages DemonstrationofshadowmappingfunctionalityusingOpenGLES3.0. Introduction ThistutorialassumesthatyoualreadyhavebasicOpenGLESknowledge,andhavereadandunderstoodtheNormalMapping,LightingandTextureCubetutorials. Overview ShadowMapping.Yellowcuberepresentsthespotlightsource. Theapplicationdisplaystwocubesonaplanewhicharelitbydirectionalandspotlights.Thelocationanddirectionofthespotlightsource(representedbyasmallyellowcubeflyingabovethescene)in3Dspaceareregularlyupdated.Thecubeandplanemodelsareshadowreceivers,butonlythecubesareshadowcasters.Theapplicationusesshadowmappingforrenderinganddisplayingshadows. Rendergeometry Intheapplicationwearerenderingahorizontallylocatedplane,ontopofwhichwelaytwocubes.Thereisalsoasinglecubeflyingabovethescenewhichrepresentsthespotlightsource.Letusnowfocusongeneratingthegeometrythatwillberendered. Intheapplicationweareusingtwoprogramobjects:oneresponsibleforrenderingthescene,whichconsistsofaplaneandtwocubeswithallthelightingandshadowsapplied,andasecondone,usedforrenderingasinglecube(theyellowoneflyingabovethescene)thatrepresentsthespotlightsource.Wewillnowfocusonthefirstprogramobject,asrenderingthesinglecubeonascreenshouldbealreadyawell-knowtechniqueforthereader(orwillbeafterreadingthistutorial). Vertexcoordinatesofthegeometrythatwillberendered. Firstofall,weneedtohavethecoordinatesofverticesthatmakeupacubicorplaneshape.Pleasenotethattherewillalsobelightingapplied,whichmeansthatwewillneednormalsaswell. Geometrydatawillbestoredandthenusedbyobjectsthataregeneratedwiththefollowingcommands: /*Generatebufferobjects.*/ GL_CHECK(glGenBuffers(6,bufferObjectIds)); /*Storebufferobjectnamesinglobalvariables. *Thevariableshavemorefriendlynames,sothatusingthemiseasier.*/ cubeCoordinatesBufferObjectId=bufferObjectIds[0]; lightRepresentationCoordinatesBufferObjectId=bufferObjectIds[1]; cubeNormalsBufferObjectId=bufferObjectIds[2]; planeCoordinatesBufferObjectId=bufferObjectIds[3]; planeNormalsBufferObjectId=bufferObjectIds[4]; uniformBlockDataBufferObjectId=bufferObjectIds[5]; /*Generatevertexarrayobjects.*/ GL_CHECK(glGenVertexArrays(3,vertexArrayObjectsNames)); /*Storevertexarrayobjectnamesinglobalvariables. *Thevariableshavemorefriendlynames,sothatusingthemiseasier.*/ cubesVertexArrayObjectId=vertexArrayObjectsNames[0]; lightRepresentationCoordinatesVertexArrayObjectId=vertexArrayObjectsNames[1]; planeVertexArrayObjectId=vertexArrayObjectsNames[2]; Thereisoneextrabufferobjectgenerated,whichIDisstoredintheuniformBlockDataBufferObjectIdvariable.Thisoneisnotneededatthisstep,soyoucanignoreit. Geometrydataisthengeneratedandcopiedtospecificbufferobjects.Formoredetailsonhowthecoordinatesofverticesarecalculated,pleaserefertotheimplementationofthosefunctions. Generategeometrydata. voidcreateDataForObjectsToBeDrawn() { /*Gettriangularrepresentationofthescenecube.StorethedatainthecubeCoordinatesarray.*/ CubeModel::getTriangleRepresentation(&cube.coordinates, &cube.numberOfElementsInCoordinatesArray, &cube.numberOfPoints, cube.scalingFactor); /*Calculatenormalvectorsforthescenecubecreatedabove.*/ CubeModel::getNormals(&cube.normals, &cube.numberOfElementsInNormalsArray); /*GettriangularrepresentationofasquaretodrawplaneinXZspace.StorethedataintheplaneCoordinatesarray.*/ PlaneModel::getTriangleRepresentation(&plane.coordinates, &plane.numberOfElementsInCoordinatesArray, &plane.numberOfPoints, plane.scalingFactor); /*Calculatenormalvectorsfortheplane.StorethedataintheplaneNormalsarray.*/ PlaneModel::getNormals(&plane.normals, &plane.numberOfElementsInNormalsArray); /*Gettriangularrepresentationofthelightcube.StorethedatainthelightRepresentationCoordinatesarray.*/ CubeModel::getTriangleRepresentation(&lightRepresentation.coordinates, &lightRepresentation.numberOfElementsInCoordinatesArray, &lightRepresentation.numberOfPoints, lightRepresentation.scalingFactor); ASSERT(cube.coordinates!=NULL,"Couldnotretrievecubecoordinates."); ASSERT(cube.normals!=NULL,"Couldnotretrievecubenormals."); ASSERT(lightRepresentation.coordinates!=NULL,"Couldnotretrievecubecoordinates."); ASSERT(plane.coordinates!=NULL,"Couldnotretrieveplanecoordinates."); ASSERT(plane.normals!=NULL,"Couldnotretrieveplanenormals."); } Fillbufferobjectswithdata. /*Bufferholdingcoordinatesoftriangleswhichmakeupthescenecubes.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER, cubeCoordinatesBufferObjectId)); GL_CHECK(glBufferData(GL_ARRAY_BUFFER, cube.numberOfElementsInCoordinatesArray*sizeof(float), cube.coordinates, GL_STATIC_DRAW)); /*Bufferholdingcoordinatesofnormalvectorsforeachvertexofthescenecubes.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER, cubeNormalsBufferObjectId)); GL_CHECK(glBufferData(GL_ARRAY_BUFFER, cube.numberOfElementsInNormalsArray*sizeof(float), cube.normals, GL_STATIC_DRAW)); /*Bufferholdingcoordinatesoftriangleswhichmakeuptheplane.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER, planeCoordinatesBufferObjectId)); GL_CHECK(glBufferData(GL_ARRAY_BUFFER, plane.numberOfElementsInCoordinatesArray*sizeof(float), plane.coordinates, GL_STATIC_DRAW)); /*Bufferholdingcoordinatesoftheplane'snormalvectors.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER, planeNormalsBufferObjectId)); GL_CHECK(glBufferData(GL_ARRAY_BUFFER, plane.numberOfElementsInNormalsArray*sizeof(float), plane.normals, GL_STATIC_DRAW)); /*Bufferholdingcoordinatesofthelightcube.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER, lightRepresentationCoordinatesBufferObjectId)); GL_CHECK(glBufferData(GL_ARRAY_BUFFER, lightRepresentation.numberOfElementsInCoordinatesArray*sizeof(float), lightRepresentation.coordinates, GL_STATIC_DRAW)); Intheprogramobject,geometryverticesarereferredtoviatheattributes,whichisratherobvious. invec4attributePosition;/*Attribute:holdingcoordinatesoftrianglesthatmakeupageometry.*/ invec3attributeNormals;/*Attribute:holdingnormals.*/ Thisiswhyweneedtoqueryfortheattributelocationwithintheprogramobjectresponsibleforscenerendering(notethatallofthefollowingfunctionsneedtobecalledfortheactiveprogramobject). cubesAndPlaneProgram.positionAttributeLocation=GL_CHECK(glGetAttribLocation(cubesAndPlaneProgram.programId,"attributePosition"));/*Attributethatisfedwiththeverticesoftrianglesthatmakeupgeometry(cubeorplane).*/ cubesAndPlaneProgram.normalsAttributeLocation=GL_CHECK(glGetAttribLocation(cubesAndPlaneProgram.programId,"attributeNormals"));/*Attributethatisfedwiththenormalvectorsforgeometry(cubeorplane).*/ Asyoucanseeabove,wearequeryingforthelocationsofcoordinatesonly,withoutspecifyingthecubeorplaneones.Thisisbecauseweareusingonlyoneprogramobjecttorenderboththeplaneandthecubes.RenderingspecificgeometryisachievedbyusingproperVertexAttribArrays.Let'slookathowitisimplemented. GL_CHECK(glBindVertexArray(cubesVertexArrayObjectId)); /*Setvaluesforcubes'normalvectors.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER,cubeNormalsBufferObjectId)); GL_CHECK(glEnableVertexAttribArray(cubesAndPlaneProgram.normalsAttributeLocation)); GL_CHECK(glVertexAttribPointer(cubesAndPlaneProgram.normalsAttributeLocation,3,GL_FLOAT,GL_FALSE,0,0)); /*Setvaluesforthecubes'coordinates.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER,cubeCoordinatesBufferObjectId)); GL_CHECK(glEnableVertexAttribArray(cubesAndPlaneProgram.positionAttributeLocation)); GL_CHECK(glVertexAttribPointer(cubesAndPlaneProgram.positionAttributeLocation,3,GL_FLOAT,GL_FALSE,0,0)); GL_CHECK(glBindVertexArray(planeVertexArrayObjectId)); /*Setvaluesforplane'snormalvectors.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER,planeNormalsBufferObjectId)); GL_CHECK(glEnableVertexAttribArray(cubesAndPlaneProgram.normalsAttributeLocation)); GL_CHECK(glVertexAttribPointer(cubesAndPlaneProgram.normalsAttributeLocation,3,GL_FLOAT,GL_FALSE,0,0)); /*Setvaluesforplane'scoordinates.*/ GL_CHECK(glBindBuffer(GL_ARRAY_BUFFER,planeCoordinatesBufferObjectId)); GL_CHECK(glEnableVertexAttribArray(cubesAndPlaneProgram.positionAttributeLocation)); GL_CHECK(glVertexAttribPointer(cubesAndPlaneProgram.positionAttributeLocation,3,GL_FLOAT,GL_FALSE,0,0)); Now,bycallingglBindVertexArray()withtheproperparameter,wecancontrolwhichobject(cubesorplane)isgoingtoberendered.Pleasereferto: GL_CHECK(glBindVertexArray(cubesVertexArrayObjectId)); GL_CHECK(glBindVertexArray(planeVertexArrayObjectId)); Thefinalthingistomaketheactualdrawcall,whichcanbeachievedby: GL_CHECK(glDrawArrays(GL_TRIANGLES,0,plane.numberOfPoints)); Wewantedtodrawtwocubesthatarelaidonaplane.ThisiswhyweusetheglDrawArraysInstanced()callratherthanglDrawArrays().Thankstothattherewillbeexactly2instancesofthesameobjectdrawnonascreen. GL_CHECK(glDrawArraysInstanced(GL_TRIANGLES,0,cube.numberOfPoints,2)); Calculateashadowmap Tocalculatetheshadowmapweneedtocreateadepthtexture,whichwillbeusedtostoretheresults.Itisachievedinsomebasicsteps,whichyoushouldalreadyknow,butletusdescribethisonemoretime. GeneratetextureobjectandbindittotheGL_TEXTURE_2Dtarget. GL_CHECK(glGenTextures(1, &shadowMap.textureName)); GL_CHECK(glBindTexture(GL_TEXTURE_2D, shadowMap.textureName)); Specifythetexturestoragedatatype. GL_CHECK(glTexStorage2D(GL_TEXTURE_2D, 1, GL_DEPTH_COMPONENT24, shadowMap.width, shadowMap.height)); Wewantedourshadowtobemoreprecise,thisiswhythedepthtextureresolutionisbiggerthannormalscenesize.Pleasereferto: window.height=height; window.width=width; shadowMap.height=window.height*2; shadowMap.width=window.width*2; Settextureobjectparameters.ThenewthinghereistosetGL_TEXTURE_COMPARE_MODEtothevalueofGL_COMPARE_REF_TO_TEXTUREwhichleadstortexturecoordinatetobecomparedtothevalueinthecurrentlybounddepthtexture. GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST)); GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST)); GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE)); GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE)); GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_FUNC, GL_LEQUAL)); GL_CHECK(glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_COMPARE_MODE, GL_COMPARE_REF_TO_TEXTURE)); Thenextthingwehavetodotoimplementtherendertotexturemechanismisto: Generateframebufferobject. GL_CHECK(glGenFramebuffers(1, &shadowMap.framebufferObjectName)); GL_CHECK(glBindFramebuffer(GL_FRAMEBUFFER, shadowMap.framebufferObjectName)); Bindthedepthtextureobjecttothedepthattachmentoftheframebufferobject. GL_CHECK(glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, shadowMap.textureName, 0)); Wewantedthespotlightsourcepositiontobeupdatedpereachframe.Thisiswhytheshadowmapwillneedtobeupdatedaswell,astheperspectivefromwhichaspotlightis"lookinginto"thesceneisdifferentforeachframe. lightProjectionMatrix=Matrix::matrixPerspective(degreesToRadians(90.0f), 1.0f, 1.0f, 50.0f); light.position.x=radius*sinf(time/2.0f); light.position.y=2.0f; light.position.z=radius*cosf(time/2.0f); /*Directionoflight.*/ light.direction.x=lookAtPoint.x-light.position.x; light.direction.y=lookAtPoint.y-light.position.y; light.direction.z=lookAtPoint.z-light.position.z; /*Normalizethelightdirectionvector.*/ light.direction.normalize(); GL_CHECK(glUniform3fv(cubesAndPlaneProgram.lightDirectionLocation,1,(float*)&light.direction)); GL_CHECK(glUniform3fv(cubesAndPlaneProgram.lightPositionLocation,1,(float*)&light.position)); Intheshader,weareusingauniform:abooleanflagindicating,whethertheplaneorcubesarebeingrendered.Thankstothat,therewillbeadifferentpositionused,whicharespecificforeachgeometry. if(shouldRenderPlane) { modelPosition=planePosition; } else { modelPosition=vec3(cubesPosition[gl_InstanceID].x,cubesPosition[gl_InstanceID].y,cubesPosition[gl_InstanceID].z); } Getuniformlocation cubesAndPlaneProgram.shouldRenderPlaneLocation=GL_CHECK(glGetUniformLocation(cubesAndPlaneProgram.programId,"shouldRenderPlane"));/*Uniformholdingabooleanvalueindicatingwhichgeometryisbeingdrawn:cubeorplane.*/ Setuniformvalue.False,ifcubesarerendered. GL_CHECK(glUniform1i(cubesAndPlaneProgram.shouldRenderPlaneLocation, false)); True,ifaplaneisrendered. GL_CHECK(glUniform1i(cubesAndPlaneProgram.shouldRenderPlaneLocation, true)); Owingtothefactthattheshadowmaptextureisbiggerthanthenormalscene(asalreadymentionedabove),wehavetoremembertoadjusttheviewport. GL_CHECK(glViewport(0,0,shadowMap.width,shadowMap.height)); Oursceneisrathersimple:therearetwocubesplacedonthetopofaplane.Wecanintroducesomeoptimisationhere,whichmeansthebackfaceswillbeculled.Wearealsosettingthepolygonoffsettoeliminatez-fightingintheshadows.Thosesettingsareusedonlyifenabled. /*SetthePolygonoffset,usedwhenrenderingtheintotheshadowmaptoeliminatez-fightingintheshadows.*/ GL_CHECK(glPolygonOffset(1.0,0.0)); GL_CHECK(glCullFace(GL_BACK)); GL_CHECK(glEnable(GL_POLYGON_OFFSET_FILL)); Whatweneedtodoistoenabledepthtesting.Whenthisisenabled,thedepthvalueswillbecomparedandtheresultwillbestoredinthedepthbuffer. /*Enabledepthtesttodocomparisonofdepthvalues.*/ GL_CHECK(glEnable(GL_DEPTH_TEST)); Inthisstep,wewanttogeneratethedepthvaluesonly,whichmeansweareallowedtodisablewritingtoeachframebuffercolourcomponent. /*Disablewritingofeachframebuffercolorcomponent.*/ GL_CHECK(glColorMask(GL_FALSE,GL_FALSE,GL_FALSE,GL_FALSE)); Finallywearereadyfortheactualrendering. draw(false); Ifwewouldliketousethegenerateddepthtexturedatainaprogramobject,itisenoughtoqueryforashadowsampleruniformlocationandsetthedepthtextureobjectasinputvalueforthisuniform. cubesAndPlaneProgram.shadowMapLocation=GL_CHECK(glGetUniformLocation(cubesAndPlaneProgram.programId,"shadowMap")); /*Setactivetexture.Shadowmaptexturewillbepassedtoshader.*/ GL_CHECK(glActiveTexture(GL_TEXTURE0)); GL_CHECK(glBindTexture(GL_TEXTURE_2D,shadowMap.textureName)); GL_CHECK(glUniform1i(cubesAndPlaneProgram.shadowMapLocation,0)); ThosearebasicallyallthestepsweneedtoproceedintheAPI.Themainmechanismoftheshadowmappingtechniqueishandledbytheprogramobject.Pleaselookattheshadersshownbelow. Vertexshadercode /*Numberofcubestobedrawn.*/ #definenumberOfCubes2 /*[Defineattributes]*/ invec4attributePosition;/*Attribute:holdingcoordinatesoftrianglesthatmakeupageometry.*/ invec3attributeNormals;/*Attribute:holdingnormals.*/ /*[Defineattributes]*/ uniformmat4cameraProjectionMatrix;/*Projectionmatrixfromcamerapointofview.*/ uniformmat4lightProjectionMatrix;/*Projectionmatrixfromlightpointofview.*/ uniformmat4lightViewMatrix;/*Viewmatrixfromlightpointofview.*/ uniformvec3cameraPosition;/*Camerapositionwhichweusetocalculateviewmatrixforfinalpass.*/ uniformvec3lightPosition;/*Vectorofpositionofspotlightsource.*/ uniformboolisCameraPointOfView;/*Iftrue:performcalculationsfromcamerapointofview,else:fromlightpointofview.*/ uniformboolshouldRenderPlane;/*Iftrue:drawplane,else:drawcubes.*/ uniformvec3planePosition;/*Positionofplaneusedtocalculatetranslationmatrixforaplane.*/ /*Uniformblockholdingdatausedforrenderingcubes(positionofcubes)-usedtocalculatetranslationmatrixforeachcubeinworldspace.*/ uniformcubesDataUniformBlock { vec4cubesPosition[numberOfCubes]; }; outvec4outputLightPosition;/*Outputvariable:vectorofpositionofspotlightsourcetranslatedintoeye-space.*/ outvec3outputNormal;/*Outputvariable:normalvectorforthecoordinates.*/ outvec4outputPosition;/*Outputvariable:vertexcoordinatesexpressedineyespace.*/ outmat4outputViewToTextureMatrix;/*Outputvariable:matrixwewilluseinthefragmentshadertosampletheshadowmapforgivenfragment.*/ voidmain() { /*Viewmatrixcalculatedfromcamerapointofview.*/ mat4cameraViewMatrix; /*Matricesandvectorsusedforcalculatingoutputvariables.*/ vec3modelPosition; mat4modelViewMatrix; mat4modelViewProjectionMatrix; /*Modelconsistsofplaneandcubes(eachofthemhasdifferentcolourandposition).*/ /*[Usedifferentpositionforaspecificgeometry]*/ if(shouldRenderPlane) { modelPosition=planePosition; } else { modelPosition=vec3(cubesPosition[gl_InstanceID].x,cubesPosition[gl_InstanceID].y,cubesPosition[gl_InstanceID].z); } /*[Usedifferentpositionforaspecificgeometry]*/ /*Createtransformationmatrix(translationofamodel).*/ mat4translationMatrix=mat4(1.0,0.0,0.0,0.0, 0.0,1.0,0.0,0.0, 0.0,0.0,1.0,0.0, modelPosition.x,modelPosition.y,modelPosition.z,1.0); /*Computematricesforcamerapointofview.*/ if(isCameraPointOfView==true) { cameraViewMatrix=mat4(1.0,0.0,0.0,0.0, 0.0,1.0,0.0,0.0, 0.0,0.0,1.0,0.0, -cameraPosition.x,-cameraPosition.y,-cameraPosition.z,1.0); /*Computemodel-viewmatrix.*/ modelViewMatrix=cameraViewMatrix*translationMatrix; /*Computemodel-view-perspectivematrix.*/ modelViewProjectionMatrix=cameraProjectionMatrix*modelViewMatrix; } /*Computematricesforlightpointofview.*/ else { /*Computemodel-viewmatrix.*/ modelViewMatrix=lightViewMatrix*translationMatrix; /*Computemodel-view-perspectivematrix.*/ modelViewProjectionMatrix=lightProjectionMatrix*modelViewMatrix; } /*[Definebiasmatrix]*/ /*Biasmatrixusedtomapvaluesfromarange(eyespacecoordinates)to<0,1>(texturecoordinates).*/ constmat4biasMatrix=mat4(0.5,0.0,0.0,0.0, 0.0,0.5,0.0,0.0, 0.0,0.0,0.5,0.0, 0.5,0.5,0.5,1.0); /*[Definebiasmatrix]*/ /*Calculatenormalmatrix.*/ mat3normalMatrix=transpose(inverse(mat3x3(modelViewMatrix))); /*Calculateandsetoutputvectors.*/ outputLightPosition=modelViewMatrix*vec4(lightPosition,1.0); outputNormal=normalMatrix*attributeNormals; outputPosition=modelViewMatrix*attributePosition; if(isCameraPointOfView) { /*[Calculatematrixthatwillbeusedtoconvertcameratoeyespace]*/ outputViewToTextureMatrix=biasMatrix*lightProjectionMatrix*lightViewMatrix*inverse(cameraViewMatrix); /*[Calculatematrixthatwillbeusedtoconvertcameratoeyespace]*/ } /*Multiplymodel-spacecoordinatesbymodel-view-projectionmatrixtobringthemintoeye-space.*/ gl_Position=modelViewProjectionMatrix*attributePosition; } Weuseoneprogramobjecttorenderthecubesandplanefromthecameraandlightpointofview.Thevertexshaderjustusesdifferentinputdatatorenderthespecificgeometryanddifferentmatricesareusedfortranslatingtheverticesintoaspecificspace.Thereishoweveroneimportantstepwhichhasnotbeenmentionedbefore. Ifwearerenderingageometryfromthespotlight’spointofview(togetdepthvalueswhicharethenstoredintheshadowMaptexture),thenweneedtosamplethetexturetogetthedepthvalueofaspecificfragment,butthistimethecamera’spointofviewistakenintoaccount.Wehavetosomehowconvertonespaceintoanother.AndthisiswhywearecalculatingtheoutputViewToTextureMatrixmatrix. Abiasmatrixhelpsuswithconvertingcoordinatesfromeyespace(fromarange)tovaluesfromtexturecoordinatesrange:<0,1>. /*Biasmatrixusedtomapvaluesfromarange(eyespacecoordinates)to<0,1>(texturecoordinates).*/ constmat4biasMatrix=mat4(0.5,0.0,0.0,0.0, 0.0,0.5,0.0,0.0, 0.0,0.0,0.5,0.0, 0.5,0.5,0.5,1.0); outputViewToTextureMatrix=biasMatrix*lightProjectionMatrix*lightViewMatrix*inverse(cameraViewMatrix); Thewholeideaisrepresentedwiththeschemashownbelow. ConvertingcameraeyespacetospotlightNDCspaceschema. Whenwegetthisvalue,wearereadytoissuethefragmentshaderoperations.Thereisdirectionallightingimplemented,whichshouldbeclearforareader.Therearealsospotlightcalculationsissued. Fragmentshadercode precisionhighpfloat; precisionhighpsampler2DShadow; invec4outputLightPosition;/*Vectorofthespotlightpositiontranslatedintoeye-space.*/ invec3outputNormal;/*Normalvectorforthecoordinates.*/ invec4outputPosition;/*Vertexcoordinatesexpressedineyespace.*/ inmat4outputViewToTextureMatrix;/*Matrixwewilluseinthefragmentshadertosampletheshadowmapforgivenfragment.*/ uniformvec4colorOfGeometry;/*Colourofthegeometry.*/ uniformvec3lightDirection;/*Normalizeddirectionvectorforthespotlight.*/ uniformsampler2DShadowshadowMap;/*Samplerofthedepthtextureusedforshadow-mapping.*/ outvec4color;/*Outputcolourvariable.*/ #definePI3.14159265358979323846 /*Structureholdingpropertiesofthedirectionallight.*/ structDirectionalLight { floatambient;/*Valueofambientintensityfordirectionallightingofascene.*/ vec3color;/*Colourofthedirectionallight.*/ vec3direction;/*Directionforthedirectionallight.*/ }; /*Structureholdingpropertiesofspotlight.*/ structSpotLight { floatambient;/*Valueofambientintensityforspotlighting.*/ floatangle;/*Anglebetweenspotlightdirectionandconeface.*/ floatspotExponent;/*Valueindicatingintensitydistributionoflight.*/ floatconstantAttenuation;/*Valueoflight'sattenuation.*/ floatlinearAttenuation;/*Valueoflinearlight'sattenuation.*/ floatquadraticAttenuation;/*Valueofquadraticlight'sattenuation.*/ vec3direction;/*Vectorofdirectionofspotlight.*/ vec4position;/*Coordinatesofpositionofspotlightsource.*/ }; voidmain() { DirectionalLightdirectionalLight; directionalLight.ambient=0.01; directionalLight.color=vec3(1.0,1.0,1.0); directionalLight.direction=vec3(0.2,-1.0,-0.2); SpotLightspotLight; spotLight.ambient=0.1; spotLight.angle=30.0; spotLight.spotExponent=2.0; spotLight.constantAttenuation=1.0; spotLight.linearAttenuation=0.1; spotLight.quadraticAttenuation=0.9; spotLight.direction=lightDirection; spotLight.position=outputLightPosition; /*Computedistancebetweenthelightpositionandthefragmentposition.*/ floatxDistanceFromLightToVertex=(spotLight.position.x-outputPosition.x); floatyDistanceFromLightToVertex=(spotLight.position.y-outputPosition.y); floatzDistanceFromLightToVertex=(spotLight.position.z-outputPosition.z); floatdistanceFromLightToVertex=sqrt((xDistanceFromLightToVertex*xDistanceFromLightToVertex)+ (yDistanceFromLightToVertex*yDistanceFromLightToVertex)+ (zDistanceFromLightToVertex*zDistanceFromLightToVertex)); /*Directionallight.*/ /*Calculatethevalueofdiffuseintensity.*/ floatdiffuseIntensity=max(0.0,-dot(outputNormal,normalize(directionalLight.direction))); /*Calculatecolourfordirectionallighting.*/ color=colorOfGeometry*vec4(directionalLight.color*(directionalLight.ambient+diffuseIntensity),1.0); /*Spotlight.*/ /*Computethedotproductbetweennormalandlightdirection.*/ floatnormalDotLight=max(dot(normalize(outputNormal),normalize(-spotLight.direction)),0.0); /*Shadow.*/ /*Positionofthevertextranslatedtotexturespace.*/ vec4vertexPositionInTexture=outputViewToTextureMatrix*outputPosition; /*Normalizedpositionofthevertextranslatedtotexturespace.*/ vec4normalizedVertexPositionInTexture=vec4(vertexPositionInTexture.x/vertexPositionInTexture.w, vertexPositionInTexture.y/vertexPositionInTexture.w, vertexPositionInTexture.z/vertexPositionInTexture.w, 1.0); /*Depthvalueretrievedfromtheshadowmap.*/ floatshadowMapDepth=textureProj(shadowMap,normalizedVertexPositionInTexture); /*Depthvalueretrievedfromdrawnmodel.*/ floatmodelDepth=normalizedVertexPositionInTexture.z; /*Calculatevectorfrompositionoflighttopositionoffragment.*/ vec3vectorFromLightToFragment=vec3(outputPosition.x-spotLight.position.x, outputPosition.y-spotLight.position.y, outputPosition.z-spotLight.position.z); /*CalculatecosinevalueofanglebetweenvectorFromLightToFragmentandvectorofspotlightdirection.*/ floatcosinusAlpha=dot(spotLight.direction,vectorFromLightToFragment)/ (sqrt(dot(spotLight.direction,spotLight.direction))* sqrt(dot(vectorFromLightToFragment,vectorFromLightToFragment))); /*Calculateangleforcosinevalue.*/ floatalpha=acos(cosinusAlpha); /* *Checkangles.IfalphaislessthanspotLight.anglethenthefragmentisinsidelightcone. *Otherwisethefragmentisoutsidethecone-itisnotlitbyspotlight. */ constfloatshadowMapBias=0.00001; if(alpha