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/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <engine/scene/camera.hpp>
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#include <engine/math/quaternion.hpp>
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#include <engine/math/projection.hpp>
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namespace scene {
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geom::ray<float, 3> camera::pick(const math::fvec2& ndc) const
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{
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const auto near = m_inv_view_projection * math::fvec4{ndc[0], ndc[1], 1.0f, 1.0f};
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const auto origin = math::fvec3(near) / near[3];
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const auto direction = math::normalize(origin - get_translation());
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return {origin, direction};
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}
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math::fvec3 camera::project(const math::fvec3& object, const math::fvec4& viewport) const
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{
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math::fvec4 result = m_view_projection * math::fvec4{object[0], object[1], object[2], 1.0f};
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result /= result[3];
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result.x() = result.x() * viewport[2] + viewport[0];
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result.y() = result.y() * viewport[3] + viewport[1];
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return math::fvec3(result);
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}
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math::fvec3 camera::unproject(const math::fvec3& window, const math::fvec4& viewport) const
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{
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math::fvec4 result;
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result[0] = ((window[0] - viewport[0]) / viewport[2]) * 2.0f - 1.0f;
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result[1] = ((window[1] - viewport[1]) / viewport[3]) * 2.0f - 1.0f;
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//result[2] = window[2] * 2.0f - 1.0f; z: [-1, 1]
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//result[2] = window[2]; // z: [0, 1]
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result[2] = 1.0f - window[2]; // z: [1, 0]
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result[3] = 1.0f;
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result = m_inv_view_projection * result;
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return math::fvec3(result) * (1.0f / result[3]);
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}
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void camera::set_perspective(float vertical_fov, float aspect_ratio, float near, float far)
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{
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// Set projection mode to perspective
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m_orthographic = false;
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// Update perspective projection parameters
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m_vertical_fov = vertical_fov;
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m_aspect_ratio = aspect_ratio;
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m_clip_near = near;
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m_clip_far = far;
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// Recalculate projection matrix (reversed depth) and its inverse
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if (m_clip_far == std::numeric_limits<float>::infinity())
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{
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std::tie(m_projection, m_inv_projection) = math::inf_perspective_half_z_reverse_inv(m_vertical_fov, m_aspect_ratio, m_clip_near);
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}
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else
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{
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std::tie(m_projection, m_inv_projection) = math::perspective_half_z_inv(m_vertical_fov, m_aspect_ratio, m_clip_far, m_clip_near);
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}
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// Recalculate view-projection matrix
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m_view_projection = m_projection * m_view;
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m_inv_view_projection = m_inv_view * m_inv_projection;
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// Recalculate view frustum
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update_frustum();
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}
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void camera::set_vertical_fov(float vertical_fov)
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{
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if (!m_orthographic)
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{
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set_perspective(vertical_fov, m_aspect_ratio, m_clip_near, m_clip_far);
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}
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}
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void camera::set_aspect_ratio(float aspect_ratio)
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{
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if (!m_orthographic)
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{
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set_perspective(m_vertical_fov, aspect_ratio, m_clip_near, m_clip_far);
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}
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}
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void camera::set_orthographic(float clip_left, float clip_right, float clip_bottom, float clip_top, float clip_near, float clip_far)
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{
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// Set projection mode to orthographic
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m_orthographic = true;
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// Update signed distances to clipping planes
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m_clip_left = clip_left;
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m_clip_right = clip_right;
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m_clip_bottom = clip_bottom;
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m_clip_top = clip_top;
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m_clip_near = clip_near;
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m_clip_far = clip_far;
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// Recalculate projection matrix (reversed depth) and its inverse
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std::tie(m_projection, m_inv_projection) = math::ortho_half_z_inv(m_clip_left, m_clip_right, m_clip_bottom, m_clip_top, m_clip_far, m_clip_near);
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// Update view-projection matrix and its inverse
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m_view_projection = m_projection * m_view;
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m_inv_view_projection = m_inv_view * m_inv_projection;
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// Update view frustum
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update_frustum();
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}
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void camera::set_exposure_value(float ev100)
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{
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m_exposure_value = ev100;
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// m_exposure_normalization = 1.0f / (std::exp2(m_exposure_value) * 1.2f);
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m_exposure_normalization = 1.0f / (std::exp2(m_exposure_value));
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}
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void camera::transformed()
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{
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// Update basis vectors
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m_forward = get_rotation() * math::fvec3{0.0f, 0.0f, -1.0f};
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m_up = get_rotation() * math::fvec3{0.0f, 1.0f, 0.0f};
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// Recalculate view matrix and its inverse
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std::tie(m_view, m_inv_view) = math::look_at_rh_inv(get_translation(), get_translation() + m_forward, m_up);
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// Update view-projection matrix and its inverse
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m_view_projection = m_projection * m_view;
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m_inv_view_projection = m_inv_view * m_inv_projection;
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// Update view frustum
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update_frustum();
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}
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void camera::update_frustum()
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{
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// Recalculate view frustum
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m_view_frustum.extract(m_view_projection);
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// Reverse half z clip-space coordinates of a cube
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constexpr math::fvec4 clip_space_cube[8] =
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{
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{-1, -1, 1, 1}, // NBL
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{ 1, -1, 1, 1}, // NBR
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{-1, 1, 1, 1}, // NTL
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{ 1, 1, 1, 1}, // NTR
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{-1, -1, 0, 1}, // FBL
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{ 1, -1, 0, 1}, // FBR
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{-1, 1, 0, 1}, // FTL
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{ 1, 1, 0, 1} // FTR
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};
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// Update bounds
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m_bounds = {math::fvec3::infinity(), -math::fvec3::infinity()};
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for (std::size_t i = 0; i < 8; ++i)
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{
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const math::fvec4 frustum_corner = m_inv_view_projection * clip_space_cube[i];
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m_bounds.extend(math::fvec3(frustum_corner) / frustum_corner[3]);
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}
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}
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} // namespace scene
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