94 lines
3 KiB
C
94 lines
3 KiB
C
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#pragma once
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#include <optional>
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#include <tiny_obj_loader.h>
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struct Scene {
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tinyobj::attrib_t attrib;
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std::vector<tinyobj::shape_t> shapes;
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std::vector<tinyobj::material_t> materials;
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bool load_from_file(const std::string_view path) {
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return tinyobj::LoadObj(&attrib, &shapes, &materials, nullptr, path.data());
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}
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};
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inline glm::vec3 fetch_position(const Scene& scene, const tinyobj::mesh_t& mesh, const int32_t index, const int32_t vertex) {
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tinyobj::index_t idx = mesh.indices[(index * 3) +vertex];
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tinyobj::real_t vx = scene.attrib.vertices[3*idx.vertex_index+0];
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tinyobj::real_t vy = scene.attrib.vertices[3*idx.vertex_index+1];
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tinyobj::real_t vz = scene.attrib.vertices[3*idx.vertex_index+2];
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return glm::vec3(vx, vy, vz);
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}
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inline glm::vec3 fetch_normal(const Scene& scene, const tinyobj::mesh_t& mesh, const int32_t index, const int32_t vertex) {
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tinyobj::index_t idx = mesh.indices[(index * 3) + vertex];
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tinyobj::real_t nx = scene.attrib.normals[3*idx.normal_index+0];
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tinyobj::real_t ny = scene.attrib.normals[3*idx.normal_index+1];
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tinyobj::real_t nz = scene.attrib.normals[3*idx.normal_index+2];
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return glm::vec3(nx, ny, nz);
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}
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struct HitResult {
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glm::vec3 position, normal;
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tinyobj::mesh_t* mesh = nullptr;
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};
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std::optional<HitResult> test_mesh(const Ray ray, const Scene& scene, const tinyobj::mesh_t& mesh, float& tClosest) {
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bool intersection = false;
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HitResult result = {};
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for (size_t i = 0; i < mesh.num_face_vertices.size(); i++) {
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const glm::vec3 v0 = fetch_position(scene, mesh, i, 0);
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const glm::vec3 v1 = fetch_position(scene, mesh, i, 1);
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const glm::vec3 v2 = fetch_position(scene, mesh, i, 2);
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float t = std::numeric_limits<float>::infinity(), u, v;
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if (intersections::ray_triangle(ray, v0, v1, v2, t, u, v)) {
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if (t < tClosest && t > epsilon) {
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const glm::vec3 n0 = fetch_normal(scene, mesh, i, 0);
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const glm::vec3 n1 = fetch_normal(scene, mesh, i, 1);
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const glm::vec3 n2 = fetch_normal(scene, mesh, i, 2);
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result.normal = (1 - u - v) * n0 + u * n1 + v * n2;
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result.position = ray.origin + ray.direction * t;
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tClosest = t;
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intersection = true;
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}
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}
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}
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if(intersection)
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return result;
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else
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return {};
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}
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std::optional<HitResult> test_scene(const Ray ray, const Scene& scene, float tClosest = std::numeric_limits<float>::infinity()) {
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bool intersection = false;
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HitResult result = {};
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for (uint32_t i = 0; i < scene.shapes.size(); i++) {
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auto mesh = scene.shapes[i].mesh;
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if(auto hit = test_mesh(ray, scene, mesh, tClosest)) {
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intersection = true;
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result = hit.value();
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result.mesh = &mesh;
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}
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}
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if(intersection)
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return result;
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else
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return {};
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}
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