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#include "renderer.hpp"
#include <cstddef>
#include <memory>
#include <array>
#include <tuple>
#include <utility>
#include "math/vector.hpp"
#include "o3d/tri.hpp"
#include "o3d/tri_deriv.hpp"
#include "o3d/polygon.hpp"
#include "o3d/mesh.hpp"
#include "fb/fb.hpp"
#include "fb/chfb.hpp"
#include "fb/pixfb.hpp"
#include "shaders/shaders.hpp"
#include "shaders/simple_shaders.hpp"
using namespace engine;
using
engine::math::Vector2,
engine::math::Vector3,
engine::math::Vector4,
engine::o3d::Triangle,
engine::o3d::TriangleDerived,
engine::o3d::DerivedVertex,
engine::o3d::Mesh,
engine::fb::CharacterFrameBuffer,
engine::fb::FrameBufferConcept,
engine::fb::PixelFrameBuffer,
engine::shaders::ShadersConcept,
engine::shaders::SimpleShaders;
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
Renderer<FrameBuffer, Shaders>::Renderer(FrameBuffer&& fb, Shaders&& shaders) : fb { std::forward<FrameBuffer>(fb) }, shaders { std::forward<Shaders>(shaders) } {
depth_buf.resize(this->fb.width() * this->fb.height());
}
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
void Renderer<FrameBuffer, Shaders>::resize(unsigned int w, unsigned int h) {
fb.resize(w, h);
depth_buf.resize(fb.width() * fb.height());
}
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
void Renderer<FrameBuffer, Shaders>::clear() {
std::fill(depth_buf.begin(), depth_buf.end(), 1.f);
fb.clear();
}
enum class TriangleSide { top, bottom };
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
void Renderer<FrameBuffer, Shaders>::draw_triangle(const Triangle& triangle) {
const auto& polygon = engine::o3d::polygon::div_by_w(engine::o3d::polygon::from_triangle_derived(triangle.to_derived()).clip_z(0.f, 1.f));
if (engine::o3d::polygon::signed_area_xy(polygon) >= 0) return;
const auto& [final_triangles_count, final_triangles]
= polygon.clip_xy(-1.f, -1.f, 1.f, 1.f)
.map_xy({ -1.f, -1.f }, { 1.f, 1.f }, { -.5f, -.5f }, { static_cast<float>(fb.width()) - .5f, static_cast<float>(fb.height()) - .5f })
.to_triangles();
for (std::size_t i = 0; i < final_triangles_count; i++)
_draw_cropped_triangle(triangle, final_triangles[i]);
}
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
void Renderer<FrameBuffer, Shaders>::draw_mesh(const Mesh& mesh) {
for (const auto& triangle_indices : mesh.indices) {
draw_triangle([&]<std::size_t... j>(std::index_sequence<j...>) -> Triangle {
return {
shaders.vertex(mesh.vertices[triangle_indices[j][0]],
mesh.normals [triangle_indices[j][1]],
mesh.uvs [triangle_indices[j][2]])
...
};
}(std::make_index_sequence<3>()));
}
}
// TODO: the renaming of w to z or the inverse is very confusing. The reason why it happens is
// because we use Vector3 to store x, y and w, which therefore gets renamed to w. We should find
// another way of doing this
template<FrameBufferConcept FrameBuffer, ShadersConcept Shaders>
void Renderer<FrameBuffer, Shaders>::_draw_cropped_triangle(const Triangle& root, const TriangleDerived<Vector3>& triangle) {
std::array<const DerivedVertex<Vector3>*, 3> sorted_vs = { &triangle.derived_vertex1, &triangle.derived_vertex2, &triangle.derived_vertex3 };
{
const auto swap_if_gt = [&](auto x, auto y) {
if (sorted_vs[x]->vertex.y > sorted_vs[y]->vertex.y) {
auto temp = sorted_vs[x];
sorted_vs[x] = sorted_vs[y];
sorted_vs[y] = temp;
}
};
swap_if_gt(0, 1);
swap_if_gt(1, 2);
swap_if_gt(0, 1);
}
auto middle_vl = *sorted_vs[1];
const float fac = (sorted_vs[1]->vertex.y - sorted_vs[0]->vertex.y) / (sorted_vs[2]->vertex.y - sorted_vs[0]->vertex.y);
const float middle_vr_vertex_w = 1.f / (1.f / sorted_vs[0]->vertex.z + fac * (1.f / sorted_vs[2]->vertex.z - 1.f / sorted_vs[0]->vertex.z));
const float fac_b0 = middle_vr_vertex_w * (1.f - fac) / sorted_vs[0]->vertex.z;
DerivedVertex<Vector3> middle_vr {
{
sorted_vs[0]->vertex.x + fac * (sorted_vs[2]->vertex.x - sorted_vs[0]->vertex.x),
sorted_vs[1]->vertex.y,
middle_vr_vertex_w
},
fac_b0 * sorted_vs[0]->b0 + (1.f - fac_b0) * sorted_vs[2]->b0,
fac_b0 * sorted_vs[0]->b1 + (1.f - fac_b0) * sorted_vs[2]->b1
};
if (middle_vr.vertex.x < middle_vl.vertex.x) {
auto temp = middle_vr;
middle_vr = middle_vl;
middle_vl = temp;
}
const auto _draw_cropped_triangle_side = [&]<TriangleSide side>() {
const int vertex_end_index = ([&]() { if constexpr (side == TriangleSide::top) return 0; else return 2; })();
const DerivedVertex<Vector3>& vertex_end = *sorted_vs[vertex_end_index];
if (vertex_end.vertex.y == sorted_vs[1]->vertex.y)
return;
int top_y;
int bottom_y;
if constexpr (side == TriangleSide::top) {
top_y = static_cast<int>(std::floor(vertex_end.vertex.y + 1.f));
bottom_y = static_cast<int>(std::ceil(sorted_vs[1]->vertex.y - 1.f));
} else {
bottom_y = static_cast<int>(std::floor(vertex_end.vertex.y));
top_y = static_cast<int>(std::ceil(sorted_vs[1]->vertex.y));
}
for (int y = top_y; y <= bottom_y; y++) {
float s = (static_cast<float>(y) - vertex_end.vertex.y)
/ (sorted_vs[1]->vertex.y - vertex_end.vertex.y);
float projected_relative_b0 = 1.f - s;
float xl = vertex_end.vertex.x + s * (middle_vl.vertex.x - vertex_end.vertex.x);
float xr = vertex_end.vertex.x + s * (middle_vr.vertex.x - vertex_end.vertex.x);
int left_x = static_cast<int>(std::ceil(xl));
int right_x = static_cast<int>(std::ceil(xr - 1.f));
for (int x = left_x; x <= right_x; x++) {
float t = (static_cast<float>(x) - xl)
/ (xr - xl);
float projected_relative_b1 = s * (1.f - t);
float point_w = 1.f /
(
projected_relative_b0 / vertex_end.vertex.z
+ projected_relative_b1 / middle_vl.vertex.z
+ (1.f - projected_relative_b0 - projected_relative_b1) / middle_vr.vertex.z
);
float relative_b0 = point_w * projected_relative_b0 / vertex_end.vertex.z;
float relative_b1 = point_w * projected_relative_b1 / middle_vl.vertex.z;
float b0 = relative_b0 * vertex_end.b0 + relative_b1 * middle_vl.b0 + (1.f - relative_b0 - relative_b1) * middle_vr.b0;
float b1 = relative_b0 * vertex_end.b1 + relative_b1 * middle_vl.b1 + (1.f - relative_b0 - relative_b1) * middle_vr.b1;
auto loc = Vector3::bilerp(root.vertex1.vertex.xyz(), root.vertex2.vertex.xyz(), root.vertex3.vertex.xyz(), b0, b1);
loc.z /= point_w;
if (loc.z >= depth_buf[x + y * fb.width()]) continue;
depth_buf[x + y * fb.width()] = loc.z;
fb.draw_point(x, y, shaders.fragment(x, y, loc,
Vector3::bilerp(root.vertex1.normal, root.vertex2.normal, root.vertex3.normal, b0, b1),
Vector2::bilerp(root.vertex1.uv, root.vertex2.uv, root.vertex3.uv, b0, b1)));
}
}
};
_draw_cropped_triangle_side.template operator()<TriangleSide::top>();
_draw_cropped_triangle_side.template operator()<TriangleSide::bottom>();
}
template class Renderer<CharacterFrameBuffer, SimpleShaders>;
template class Renderer<PixelFrameBuffer, SimpleShaders>;
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