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#include "camera.h"
#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}, fov {fov}, aspect {aspect}, near {zNear}, far {zFar},
projection {glm::perspective(fov, aspect, zNear, zFar)}
{
updateView();
}
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::vec3, 4>
Camera::extentsAtDist(const float dist) const
{
const auto adjustToSeafloor = [this](glm::vec3 & target) {
const auto vec = glm::normalize(target - position);
constexpr glm::vec3 seafloor {0, 0, -1.5};
float outdist;
if (glm::intersectRayPlane(position, vec, seafloor, ::up, outdist)) {
target = vec * outdist + position;
}
};
const auto depth = -(2.f * (dist - near) * far) / (dist * (near - far)) - 1.f;
static constexpr const std::array extents {-1.F, 1.F};
std::array<glm::vec3, 4> out {};
auto outitr = out.begin();
for (auto x : extents) {
for (auto y : extents) {
const glm::vec4 in {x, y, depth, 1.f};
const auto out = inverseViewProjection * in;
*outitr = out / out.w;
if (outitr->z < -1.5f) {
adjustToSeafloor(*outitr);
}
outitr++;
}
}
return out;
}
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