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Nick Fisher
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ios/include/ibl/Cubemap.h
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199
ios/include/ibl/Cubemap.h
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/*
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef IBL_CUBEMAP_H
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#define IBL_CUBEMAP_H
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#include <ibl/Image.h>
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#include <utils/compiler.h>
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#include <math/vec4.h>
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#include <math/vec3.h>
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#include <math/vec2.h>
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#include <algorithm>
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namespace filament {
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namespace ibl {
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/**
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* Generic cubemap class. It handles writing / reading into the 6 faces of a cubemap.
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*
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* Seamless trilinear filtering is handled.
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*
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* This class doesn't own the face data, it's just a "view" on the 6 images.
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*
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* @see CubemapUtils
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*
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*/
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class UTILS_PUBLIC Cubemap {
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public:
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/**
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* Initialize the cubemap with a given size, but no face is set and no memory is allocated.
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*
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* Usually Cubemaps are created using CubemapUtils.
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*
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* @see CubemapUtils
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*/
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explicit Cubemap(size_t dim);
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Cubemap(Cubemap&&) = default;
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Cubemap& operator=(Cubemap&&) = default;
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~Cubemap();
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enum class Face : uint8_t {
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PX = 0, // left +----+
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NX, // right | PY |
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PY, // bottom +----+----+----+----+
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NY, // top | NX | PZ | PX | NZ |
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PZ, // back +----+----+----+----+
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NZ // front | NY |
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// +----+
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};
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using Texel = filament::math::float3;
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//! releases all images and reset the cubemap size
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void resetDimensions(size_t dim);
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//! assigns an image to a face.
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void setImageForFace(Face face, const Image& image);
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//! retrieves the image attached to a face
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inline const Image& getImageForFace(Face face) const;
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//! retrieves the image attached to a face
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inline Image& getImageForFace(Face face);
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//! computes the center of a pixel at coordinate x, y
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static inline filament::math::float2 center(size_t x, size_t y);
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//! computes a direction vector from a face and a location of the center of pixel in an Image
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inline filament::math::float3 getDirectionFor(Face face, size_t x, size_t y) const;
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//! computes a direction vector from a face and a location in pixel in an Image
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inline filament::math::float3 getDirectionFor(Face face, float x, float y) const;
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//! samples the cubemap at the given direction using nearest neighbor filtering
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inline Texel const& sampleAt(const filament::math::float3& direction) const;
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//! samples the cubemap at the given direction using bilinear filtering
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inline Texel filterAt(const filament::math::float3& direction) const;
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//! samples an image at the given location in pixel using bilinear filtering
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static Texel filterAt(const Image& image, float x, float y);
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static Texel filterAtCenter(const Image& image, size_t x, size_t y);
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//! samples two cubemaps in a given direction and lerps the result by a given lerp factor
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static Texel trilinearFilterAt(const Cubemap& c0, const Cubemap& c1, float lerp,
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const filament::math::float3& direction);
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//! reads a texel at a given address
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inline static const Texel& sampleAt(void const* data) {
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return *static_cast<Texel const*>(data);
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}
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//! writes a texel at a given address
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inline static void writeAt(void* data, const Texel& texel) {
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*static_cast<Texel*>(data) = texel;
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}
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//! returns the size of the cubemap in pixels
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size_t getDimensions() const;
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/**
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* Prepares a cubemap for seamless access to its faces.
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*
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* @warning All faces of the cubemap must be backed-up by the same Image, and must already
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* be spaced by 2 lines/rows.
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*/
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void makeSeamless();
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struct Address {
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Face face;
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float s = 0;
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float t = 0;
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};
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//! returns the face and texture coordinates of the given direction
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static Address getAddressFor(const filament::math::float3& direction);
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private:
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size_t mDimensions = 0;
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float mScale = 1;
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float mUpperBound = 0;
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Image mFaces[6];
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};
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// ------------------------------------------------------------------------------------------------
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inline const Image& Cubemap::getImageForFace(Face face) const {
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return mFaces[int(face)];
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}
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inline Image& Cubemap::getImageForFace(Face face) {
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return mFaces[int(face)];
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}
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inline filament::math::float2 Cubemap::center(size_t x, size_t y) {
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return { x + 0.5f, y + 0.5f };
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}
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inline filament::math::float3 Cubemap::getDirectionFor(Face face, size_t x, size_t y) const {
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return getDirectionFor(face, x + 0.5f, y + 0.5f);
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}
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inline filament::math::float3 Cubemap::getDirectionFor(Face face, float x, float y) const {
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// map [0, dim] to [-1,1] with (-1,-1) at bottom left
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float cx = (x * mScale) - 1;
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float cy = 1 - (y * mScale);
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filament::math::float3 dir;
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const float l = std::sqrt(cx * cx + cy * cy + 1);
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switch (face) {
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case Face::PX: dir = { 1, cy, -cx }; break;
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case Face::NX: dir = { -1, cy, cx }; break;
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case Face::PY: dir = { cx, 1, -cy }; break;
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case Face::NY: dir = { cx, -1, cy }; break;
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case Face::PZ: dir = { cx, cy, 1 }; break;
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case Face::NZ: dir = { -cx, cy, -1 }; break;
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}
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return dir * (1 / l);
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}
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inline Cubemap::Texel const& Cubemap::sampleAt(const filament::math::float3& direction) const {
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Cubemap::Address addr(getAddressFor(direction));
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const size_t x = std::min(size_t(addr.s * mDimensions), mDimensions - 1);
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const size_t y = std::min(size_t(addr.t * mDimensions), mDimensions - 1);
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return sampleAt(getImageForFace(addr.face).getPixelRef(x, y));
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}
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inline Cubemap::Texel Cubemap::filterAt(const filament::math::float3& direction) const {
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Cubemap::Address addr(getAddressFor(direction));
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addr.s = std::min(addr.s * mDimensions, mUpperBound);
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addr.t = std::min(addr.t * mDimensions, mUpperBound);
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return filterAt(getImageForFace(addr.face), addr.s, addr.t);
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}
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} // namespace ibl
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} // namespace filament
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#endif /* IBL_CUBEMAP_H */
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