1mjb – January 22, 2013Oregon State UniversityComputer GraphicsCube MappingMike BaileyOregon State Universitymjb – January 22, 2013Oregon State UniversityComputer GraphicsWhat is Cube Mapping?Cube Mapping is the process of creating a representation of an object’s surrounding environment as a collection of 6 images, grouped together as a single “cube map texture”. mjb – January 22, 2013Oregon State UniversityComputer GraphicsThink of it as a Folding Boxmjb – January 22, 2013Oregon State UniversityComputer GraphicsBackBottomLeftTopFront Righthttp://codemonsters.de/home/content.php?show=cubemapsUsing Cube Mapping toModel an Environmentmjb – January 22, 2013Oregon State UniversityComputer GraphicsKelley Engineering Centermjb – January 22, 2013Oregon State UniversityComputer GraphicsCube Map Texture Lookup:Given an (s,t,p) direction vector , what (r,g,b) does that correspond to?• Let L be the texture coordinate of (s, t, and p) with the largest magnitude• L determines which of the 6 2D texture “walls” is being hit by the vector (-X in this case)• The texture coordinates in that texture are the remaining two texture coordinates divided by L: (a/L,b/L)vec3 ReflectVector = reflect( vec3 eyeDir, vec3 normal );vec3 RefractVector = refract( vec3 eyeDir, vec3 normal, float Eta );-Z-Y+Y-X+XBuilt-in GLSL functions2mjb – January 22, 2013Oregon State UniversityComputer GraphicsCube Map of the World-Y+Z-Z+Y-X +Xmjb – January 22, 2013Oregon State UniversityComputer GraphicsCreating a Globe from the World Cubemap(some shapes map better than others…)Use the normal (nx,ny,nz) as the (s,t,p) for the lookup(some shapes map better than others…)mjb – January 22, 2013Oregon State UniversityComputer Graphicsout vec3 vNormal;void main( ){vNormal = normalize( aNormal );gl_Position = uModelViewProjectionMatrix * aVertex;}uniform samplerCube uTexUnit;in vec3 vNormal;out vec4 fFragColor;void main( ){vec4 newcolor = textureCube( uTexUnit, normalize(vNormal) );fFragColor = newcolor;}Creating a Globe from the World Cubemapmjb – January 22, 2013Oregon State UniversityComputer GraphicsUsing the Cube Map for Reflectionmjb – January 22, 2013Oregon State UniversityComputer GraphicsUsing the Cube Map for Reflectionout vec3 vReflectVector;void main( ){vec3 ECposition = ( uModelViewMatrix * aVertex ).xyz;vec3 eyeDir = ECposition – vec3(0.,0.,0.); // vector from eye to ptvec3 normal = normalize( uNormalMatrix * aNormal );vReflectVector = reflect( eyeDir, normal );gl_Position = uModelViewProjectionMatrix * aVertex;}in vec3 vReflectVector;uniform samplerCube uReflectUnit;out vec4 fFragColor;void main( ){vec4 newcolor = textureCube(u ReflectUnit, vReflectVector );fFragColor = newcolor;}mjb – January 22, 2013Oregon State UniversityComputer GraphicsUsing the Cube Map for Refraction3mjb – January 22, 2013Oregon State UniversityComputer GraphicsUsing the Cube Map for Refractionout vec3 vRefractVector;out vec3 vReflectVector;uniform float uEta;void main( ){vec3 ECposition = vec3( uModelViewMatrix * aVertex );vec3 eyeDir = normalize( ECposition – vec3(0.,0.,0. ) ); // vector from eye to ptvec3 normal = normalize( uNormalMatrix * aNormal );vRefractVector = refract( eyeDir, normal, uEta );vReflectVector = reflect( eyeDir, normal );gl_Position = uModelViewProjectionMatrix * aVertex;}in vec3 vReflectVector;in vec3 vRefractVector;out vec4 fFragColor;uniform float uMix;uniform samplerCube uReflectUnit;uniform samplerCube uRefractUnit;const vec4 WHITE = vec4( 1.,1.,1.,1. );void main( ){vec4 refractcolor = textureCube( uRefractUnit, vRefractVector );vec4 reflectcolor = textureCube( uReflectUnit, vReflectVector );refractcolor = mix( refractcolor, WHITE, .3 );fFragColor = mix( refractcolor, reflectcolor, uMix );}mjb – January 22, 2013Oregon State UniversityComputer Graphicsmjb – January 22, 2013Oregon State UniversityComputer Graphicsmjb – January 22, 2013Oregon State UniversityComputer