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#include "camera.h"
#include <collections.h>
#include <glm/gtx/transform.hpp>
#include <maths.h>
#include <ray.h>
Camera::Camera(GlobalPosition3D pos, Angle fov, Angle aspect, GlobalDistance zNear, GlobalDistance zFar) :
position {pos}, forward {::north}, up {::up}, near {zNear}, far {zFar},
projection {
glm::perspective(fov, aspect, static_cast<RelativeDistance>(zNear), static_cast<RelativeDistance>(zFar))},
viewProjection {}, inverseViewProjection {}
{
updateView();
}
Ray
Camera::unProject(const ScreenRelCoord & mouse) const
{
static constexpr const glm::vec4 screen {0, 0, 1, 1};
const auto mouseProjection = glm::lookAt(::origin, forward, up);
return {position, glm::normalize(glm::unProject(mouse || 1.F, mouseProjection, projection, screen))};
}
void
Camera::updateView()
{
viewProjection = projection * glm::lookAt(origin, forward, up);
inverseViewProjection = glm::inverse(viewProjection);
}
Direction3D
Camera::upFromForward(const Direction3D & forward)
{
const auto right = glm::cross(forward, ::down);
return glm::cross(forward, right);
}
std::array<GlobalPosition4D, 4>
Camera::extentsAtDist(const GlobalDistance dist) const
{
const auto clampToSeaFloor = [this, dist](GlobalPosition3D target) -> GlobalPosition4D {
target += position;
if (target.z < -1500) {
const CalcPosition3D diff = target - position;
const CalcDistance limit = -1500 - position.z;
return {position + GlobalPosition3D((limit * diff) / diff.z), (limit * dist) / diff.z};
}
return {target, dist};
};
const auto depth = -(2.F * (static_cast<float>(dist - near)) * static_cast<float>(far))
/ (static_cast<float>(dist) * (static_cast<float>(near - far)))
- 1.F;
static constexpr const std::array extents {-1.F, 1.F};
static constexpr const auto cartesianExtents = extents * extents;
return cartesianExtents * [&depth, this, &clampToSeaFloor](const auto & extent) {
const glm::vec4 in {extent.first, extent.second, depth, 1.F};
return clampToSeaFloor(perspective_divide(inverseViewProjection * in));
};
}
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