Package apple.glkit

Class GLKReflectionMapEffect

  • All Implemented Interfaces:
    GLKNamedEffect, NSObject
    public class GLKReflectionMapEffect
extends GLKBaseEffect
implements GLKNamedEffect
    GLKReflectionMapEffect GLKReflectionMapEffect is a subclass of GLKBaseEffect. It is expected that GLKBaseEffect functionality will be used in combination with GLKReflectionMapEffect. GLKReflectionMapEffect implements common reflection mapping functionality as is used by many of todays games and simulations. A reflection or environment map can be thought of as a texture mapped polyhedral or spherical mesh that encloses a 3D model. When the model is rendered surface normals from the model are used to calculate reflection vectors which intersect the environment map at some location. The environment map texture color at this location is used to impart a modulated environment map color on the model giving the appearance that the shiny model is reflecting its surroundings to the viewer. The polyhedral shape used for GLKReflectionMapEffect is a cube. Because reflection mapping relies on surface normals to compute the intersection between reflected rays and the environment map the GLKVertexAttribNormal array must be enabled in order for GLKReflectionMapEffect to work properly. The normals are always normalized. GLKReflectionMapEffect requires at least an OpenGL ES 2.0 context on iOS and an OpenGL Core Profile context on OS X. This context must be initialized and made current prior to creating or initializing GLKReflectionMapEffect instances. No OpenGL context state settings are modified when a GLKReflectionMapEffect instance is created or its properties set. When -[GLKReflectionMapEffect prepareToDraw] is called it modifies the following state: GL_CURRENT_PROGRAM GL_TEXTURE_BINDING_CUBE_MAP For performance reasons GLKReflectionMapEffect does not restore any of these state settings. It is up to the client application to save/restore/set these state elements as they choose. A cube mapped texture name must be provided to GLKReflectionMapEffect to provide it texture data for the 6 faces of the environment map. GLKReflectionMapEffect reflection vectors are computed in eye space per section 2.11.4 of the OpenGL 2.1 desktop specification for the GL_REFLECTION_MAP texgen mode. Typical reflection mapping uses an environment map with a fixed position (e.g. the sky in a real world rendering) and will accurately map the reflection map on the model regardless of the modelview transformation. To achieve this effect decompose the modelview matrix into its model and view components (i.e. the transforms on the object are the model and the transforms on the view are the camera). Then undo the viewing transform by inverting the viewing matrix - call this Vinv. Now, starting with Vinv, treat it as the canonical normal matrix by applying an inverse transpose to it and choosing the upper 3x3 elements of the result. inverseTranspose(Vinv) simplifies to Vtranspose. To apply this result to GLKReflectionMapEffect set its matrix property as follows: reflectionMapEffect.matrix = GLKMatrix4GetMatrix3(Vtranspose); to get correct, view-angle independent reflection mapping. The following (5) steps are required to use GLKReflectionMapEffect: (1) Allocate and initialize an instance of GLKReflectionMapEffect reflectionMapEffect = [[GLKReflectionMapEffect alloc] init]; (2) Initialize vertex attribute / vertex array state preferrably with a vertex array object for the model or scene to be drawn. glGenVertexArraysOES(1, &vaoName); glBindVertexArrayOES(vaoName); // Create and initialize VBO for each vertex attribute // The example below shows an example of setup up the position and normal vertex attributes. // Specifying and binding a GLKVertexAttribNormal array attribute is required for GLKReflectionMapEffect // to work properly. The normals are always normalized. glGenBuffers(1, &positionVBO); glBindBuffer(positionVBO); glBufferData(GL_ARRAY_BUFFER, vboSize, dataBufPtr, GL_STATIC_DRAW); glVertexAttribPointer(GLKVertexAttribPosition, size, type, normalize, stride, NULL); glGenBuffers(1, &normalVBO); glBindBuffer(normalVBO); glBufferData(GL_ARRAY_BUFFER, vboSize, dataBufPtr, GL_STATIC_DRAW); glVertexAttribPointer(GLKVertexAttribNormal, size, type, normalize, stride, NULL); ... repeat the steps above for other desired vertex attributes glBindVertexArrayOES(0); // unbind the VAO we created above (3) Create a cube map texture for the reflection map glGenTextures(1, &textureCubeMap); glBindTexture(GL_TEXTURE_CUBE_MAP, textureCubeMap); glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); GLenum cubeMapBase = GL_TEXTURE_CUBE_MAP_POSITIVE_X; for(face = 0; face < 6; face++) glTexImage2D(cubeMapBase + face, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_SHORT_5_6_5, faceData[face]); (4) Set the textureCubeMap property to our new GL cube map and turn on reflection mapping reflectionMapEffect.enable = GL_TRUE; reflectionMapEffect.textureCubeMap = textureCubeMap; // created in step (2) above (5) For each frame drawn: Update properties that change per frame. Synchronize the changed effect state by calling -[GLKReflectionMapEffect prepareToDraw]. Draw the model with the effect reflectionMapEffect.transform.modelviewMatrix = modelviewMatrix; [reflectionMapEffect prepareToDraw]; glBindVertexArrayOES(vaoName); glDrawArrays(GL_TRIANGLE_STRIP, 0, vertCt);

    • Constructor Detail

      • GLKReflectionMapEffect

        protected GLKReflectionMapEffect​(org.moe.natj.general.Pointer peer)

    • Method Detail

      • accessInstanceVariablesDirectly

        public static boolean accessInstanceVariablesDirectly()

      • allocWithZone

        public static java.lang.Object allocWithZone​(org.moe.natj.general.ptr.VoidPtr zone)

      • automaticallyNotifiesObserversForKey

        public static boolean automaticallyNotifiesObserversForKey​(java.lang.String key)

      • cancelPreviousPerformRequestsWithTarget

        public static void cancelPreviousPerformRequestsWithTarget​(java.lang.Object aTarget)

      • cancelPreviousPerformRequestsWithTargetSelectorObject

        public static void cancelPreviousPerformRequestsWithTargetSelectorObject​(java.lang.Object aTarget,
                                                                         org.moe.natj.objc.SEL aSelector,
                                                                         java.lang.Object anArgument)

      • classFallbacksForKeyedArchiver

        public static NSArray<java.lang.String> classFallbacksForKeyedArchiver()

      • classForKeyedUnarchiver

        public static org.moe.natj.objc.Class classForKeyedUnarchiver()

      • debugDescription_static

        public static java.lang.String debugDescription_static()

      • description_static

        public static java.lang.String description_static()

      • hash_static

        public static long hash_static()

      • instanceMethodSignatureForSelector

        public static NSMethodSignature instanceMethodSignatureForSelector​(org.moe.natj.objc.SEL aSelector)

      • instancesRespondToSelector

        public static boolean instancesRespondToSelector​(org.moe.natj.objc.SEL aSelector)

      • isSubclassOfClass

        public static boolean isSubclassOfClass​(org.moe.natj.objc.Class aClass)

      • keyPathsForValuesAffectingValueForKey

        public static NSSet<java.lang.String> keyPathsForValuesAffectingValueForKey​(java.lang.String key)

      • new_objc

        public static java.lang.Object new_objc()

      • resolveClassMethod

        public static boolean resolveClassMethod​(org.moe.natj.objc.SEL sel)

      • resolveInstanceMethod

        public static boolean resolveInstanceMethod​(org.moe.natj.objc.SEL sel)

      • setVersion_static

        public static void setVersion_static​(long aVersion)

      • superclass_static

        public static org.moe.natj.objc.Class superclass_static()

      • version_static

        public static long version_static()

      • setMatrix

        public void setMatrix​(GLKMatrix3 value)
        Identity