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#include "camera.h"
#include <collections.hpp>
#include <glm/gtx/intersect.hpp> // IWYU pragma: keep
#include <glm/gtx/transform.hpp> // IWYU pragma: keep
#include <maths.h>
#include <ray.hpp>
Camera::Camera(glm::vec3 pos, float fov, float aspect, float zNear, float zFar) :
position {pos}, forward {::north}, up {::up}, near {zNear}, far {zFar}, projection {glm::perspective(
fov, aspect, zNear, zFar)},
viewProjection {projection * glm::lookAt(position, position + forward, up)}, inverseViewProjection {
glm::inverse(viewProjection)}
{
}
Ray
Camera::unProject(const glm::vec2 & 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, mouseProjection, projection, screen))};
}
void
Camera::updateView()
{
viewProjection = projection * glm::lookAt(position, position + forward, up);
inverseViewProjection = glm::inverse(viewProjection);
}
glm::vec3
Camera::upFromForward(const glm::vec3 & forward)
{
const auto right = glm::cross(forward, ::down);
return glm::cross(forward, right);
}
std::array<glm::vec4, 4>
Camera::extentsAtDist(const float dist) const
{
const auto clampToSeaFloor = [this, dist](const glm::vec3 & target) {
if (target.z < -1.5F) {
const auto vec = glm::normalize(target - position);
constexpr glm::vec3 seafloor {0, 0, -1.5F};
float outdist;
if (glm::intersectRayPlane(position, vec, seafloor, ::up, outdist)) {
return (vec * outdist + position) ^ outdist;
}
}
return target ^ dist;
};
const auto depth = -(2.F * (dist - near) * far) / (dist * (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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