83 lines
2.6 KiB
C
83 lines
2.6 KiB
C
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#pragma once
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#include "Library.h"
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#include "Math.h"
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#include <glm/glm.hpp>
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namespace CesiumUtility {
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/**
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* @brief Functions to handle compressed attributes in different formats
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*/
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class CESIUMUTILITY_API AttributeCompression final {
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public:
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/**
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* @brief Decodes a unit-length vector in 'oct' encoding to a normalized
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* 3-component vector.
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*
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* @param x The x component of the oct-encoded unit length vector.
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* @param y The y component of the oct-encoded unit length vector.
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* @param rangeMax The maximum value of the SNORM range. The encoded vector is
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* stored in log2(rangeMax+1) bits.
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* @returns The decoded and normalized vector.
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*/
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template <
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typename T,
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class = typename std::enable_if<std::is_unsigned<T>::value>::type>
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static glm::dvec3 octDecodeInRange(T x, T y, T rangeMax) {
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glm::dvec3 result;
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result.x = CesiumUtility::Math::fromSNorm(x, rangeMax);
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result.y = CesiumUtility::Math::fromSNorm(y, rangeMax);
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result.z = 1.0 - (glm::abs(result.x) + glm::abs(result.y));
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if (result.z < 0.0) {
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const double oldVX = result.x;
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result.x =
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(1.0 - glm::abs(result.y)) * CesiumUtility::Math::signNotZero(oldVX);
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result.y =
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(1.0 - glm::abs(oldVX)) * CesiumUtility::Math::signNotZero(result.y);
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}
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return glm::normalize(result);
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}
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/**
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* @brief Decodes a unit-length vector in 2 byte 'oct' encoding to a
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* normalized 3-component vector.
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*
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* @param x The x component of the oct-encoded unit length vector.
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* @param y The y component of the oct-encoded unit length vector.
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* @returns The decoded and normalized vector.
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*
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* @see AttributeCompression::octDecodeInRange
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*/
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static glm::dvec3 octDecode(uint8_t x, uint8_t y) {
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constexpr uint8_t rangeMax = 255;
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return AttributeCompression::octDecodeInRange(x, y, rangeMax);
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}
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/**
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* @brief Decodes a RGB565-encoded color to a 3-component vector
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* containing the normalized RGB values.
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*
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* @param value The RGB565-encoded value.
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* @returns The normalized RGB values.
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*/
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static glm::dvec3 decodeRGB565(const uint16_t value) {
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constexpr uint16_t mask5 = (1 << 5) - 1;
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constexpr uint16_t mask6 = (1 << 6) - 1;
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constexpr float normalize5 = 1.0f / 31.0f; // normalize [0, 31] to [0, 1]
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constexpr float normalize6 = 1.0f / 63.0f; // normalize [0, 63] to [0, 1]
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const uint16_t red = static_cast<uint16_t>(value >> 11);
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const uint16_t green = static_cast<uint16_t>((value >> 5) & mask6);
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const uint16_t blue = value & mask5;
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return glm::dvec3(red * normalize5, green * normalize6, blue * normalize5);
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};
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};
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} // namespace CesiumUtility
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