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#include "renderer.h"
#include <array>
#include <cmath>
#include <algorithm>
#include <memory>
#include "math/vector.h"
#include "o3d/vertex.h"
#include "o3d/deriv_vertex.h"
#include "o3d/tri_vertex.h"
#include "o3d/tri_deriv_vertex.h"
#include "o3d/vertex_data.h"
using namespace engine;
Renderer::Renderer(std::unique_ptr<fb::FrameBuffer> fb) : fb{std::move(fb)} {
depth_buf.resize(this->fb->width() * this->fb->height());
}
void Renderer::resize(unsigned int w, unsigned int h) {
fb->resize(w, h);
depth_buf.resize(fb->width() * fb->height());
}
unsigned int Renderer::width() const {
return fb->width();
}
unsigned int Renderer::height() const {
return fb->height();
}
void Renderer::clear() {
std::fill(depth_buf.begin(), depth_buf.end(), 1.f);
fb->clear();
}
void Renderer::_draw_cropped_triangle(o3d::TriangleVertex4 root, o3d::TriangleDerivedVertex4 triangle) {
std::array<o3d::DerivedVertex4*, 3> sorted_vs = { &triangle.derived_vertex1, &triangle.derived_vertex2, &triangle.derived_vertex3 };
#define SWAP_IF_LT(X,Y) ({ \
if (sorted_vs[X]->point.y < sorted_vs[Y]->point.y) { \
auto temp = sorted_vs[X]; \
sorted_vs[X] = sorted_vs[Y]; \
sorted_vs[Y] = temp; \
} \
})
SWAP_IF_LT(1, 0);
SWAP_IF_LT(2, 1);
SWAP_IF_LT(1, 0);
#undef SWAP_IF_LT
auto middle_vl = *sorted_vs[1];
const float fac = (sorted_vs[1]->point.y - sorted_vs[0]->point.y) / (sorted_vs[2]->point.y - sorted_vs[0]->point.y);
const float fac_b0 = (1.f - fac) / sorted_vs[0]->point.w / ((1.f - fac) / sorted_vs[0]->point.w + fac / sorted_vs[2]->point.w);
o3d::DerivedVertex4 middle_vr{
{
sorted_vs[0]->point.x + fac * (sorted_vs[2]->point.x - sorted_vs[0]->point.x),
sorted_vs[1]->point.y,
fac_b0 * sorted_vs[0]->point.z + (1.f - fac_b0) * sorted_vs[2]->point.z,
1.f / (1.f / sorted_vs[0]->point.w + fac * (1.f / sorted_vs[2]->point.w - 1.f / sorted_vs[0]->point.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.point.x < middle_vl.point.x) {
auto temp = middle_vr;
middle_vr = middle_vl;
middle_vl = temp;
}
// top triangle
{
if (sorted_vs[0]->point.y != sorted_vs[1]->point.y) {
int top_y = static_cast<int>(std::floor(sorted_vs[0]->point.y + 1.f));
int bottom_y = static_cast<int>(std::ceil(sorted_vs[1]->point.y - 1.f));
for (int y = top_y; y <= bottom_y; y++) {
float iy = static_cast<float>(y);
float s = (iy - sorted_vs[0]->point.y) / (sorted_vs[1]->point.y - sorted_vs[0]->point.y);
float sub_bb0 = 1.f - s;
float xl = sorted_vs[0]->point.x + s * (middle_vl.point.x - sorted_vs[0]->point.x);
float xr = sorted_vs[0]->point.x + s * (middle_vr.point.x - sorted_vs[0]->point.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 ix = static_cast<float>(x);
float t = (ix - xl) / (xr - xl);
float sub_bb1 = s * (1.f - t);
float b_fac = 1.f / (sub_bb0 / sorted_vs[0]->point.w + sub_bb1 / middle_vl.point.w + (1.f - sub_bb0 - sub_bb1) / middle_vr.point.w);
float sub_b0 = b_fac * sub_bb0 / sorted_vs[0]->point.w;
float sub_b1 = b_fac * sub_bb1 / middle_vl.point.w;
float b0 = sub_b0 * sorted_vs[0]->b0 + sub_b1 * middle_vl.b0 + (1.f - sub_b0 - sub_b1) * middle_vr.b0;
float b1 = sub_b0 * sorted_vs[0]->b1 + sub_b1 * middle_vl.b1 + (1.f - sub_b0 - sub_b1) * middle_vr.b1;
math::Vector3 loc{
b0 * root.vertex1.point.x + b1 * root.vertex2.point.x + (1.f - b0 - b1) * root.vertex3.point.x,
b0 * root.vertex1.point.y + b1 * root.vertex2.point.y + (1.f - b0 - b1) * root.vertex3.point.y,
b0 * root.vertex1.point.z + b1 * root.vertex2.point.z + (1.f - b0 - b1) * root.vertex3.point.z
};
if (loc.z < depth_buf[x + y * fb->width()]) {
depth_buf[x + y * fb->width()] = loc.z;
fb->draw_point(x, y, loc, o3d::VertexData::bilerp(root.vertex1.data, root.vertex2.data, root.vertex3.data, b0, b1));
}
}
}
}
}
// bottom triangle
{
if (sorted_vs[1]->point.y != sorted_vs[2]->point.y) {
int bottom_y = static_cast<int>(std::floor(sorted_vs[2]->point.y));
int top_y = static_cast<int>(std::ceil(sorted_vs[1]->point.y));
for (int y = top_y; y <= bottom_y; y++) {
float iy = static_cast<float>(y);
float s = (iy - sorted_vs[2]->point.y) / (sorted_vs[1]->point.y - sorted_vs[2]->point.y);
float sub_bb0 = 1.f - s;
float xl = sorted_vs[2]->point.x + s * (middle_vl.point.x - sorted_vs[2]->point.x);
float xr = sorted_vs[2]->point.x + s * (middle_vr.point.x - sorted_vs[2]->point.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 ix = static_cast<float>(x);
float t = (ix - xl) / (xr - xl);
float sub_bb1 = s * (1.f - t);
float b_fac = 1.f / (sub_bb0 / sorted_vs[2]->point.w + sub_bb1 / middle_vl.point.w + (1.f - sub_bb0 - sub_bb1) / middle_vr.point.w);
float sub_b0 = b_fac * sub_bb0 / sorted_vs[2]->point.w;
float sub_b1 = b_fac * sub_bb1 / middle_vl.point.w;
float b0 = sub_b0 * sorted_vs[2]->b0 + sub_b1 * middle_vl.b0 + (1.f - sub_b0 - sub_b1) * middle_vr.b0;
float b1 = sub_b0 * sorted_vs[2]->b1 + sub_b1 * middle_vl.b1 + (1.f - sub_b0 - sub_b1) * middle_vr.b1;
math::Vector3 loc{
b0 * root.vertex1.point.x + b1 * root.vertex2.point.x + (1.f - b0 - b1) * root.vertex3.point.x,
b0 * root.vertex1.point.y + b1 * root.vertex2.point.y + (1.f - b0 - b1) * root.vertex3.point.y,
b0 * root.vertex1.point.z + b1 * root.vertex2.point.z + (1.f - b0 - b1) * root.vertex3.point.z
};
if (loc.z < depth_buf[x + y * fb->width()]) {
depth_buf[x + y * fb->width()] = loc.z;
fb->draw_point(x, y, loc, o3d::VertexData::bilerp(root.vertex1.data, root.vertex2.data, root.vertex3.data, b0, b1));
}
}
}
}
}
}
void Renderer::draw_triangle(o3d::TriangleVertex4 triangle) {
for (auto t1 : triangle.to_derived().crop_z_out(-1.f, 1.f)) {
for (auto t2 : t1.div_by_w().perspective_crop_xy_out(-1.f, 1.f, -1.f, 1.f)) {
auto pp1 = t2.derived_vertex1.point.xy();
auto pp2 = t2.derived_vertex2.point.xy();
auto pp3 = t2.derived_vertex3.point.xy();
if ((pp2 - pp1).det(pp3 - pp1) >= 0.f) continue;
float fw_over_2 = static_cast<float>(fb->width()) / 2.f, fh_over_2 = static_cast<float>(fb->height()) / 2.f;
t2.derived_vertex1.point.x = (t2.derived_vertex1.point.x + 1.f) * fw_over_2 - .5f;
t2.derived_vertex1.point.y = (t2.derived_vertex1.point.y + 1.f) * fh_over_2 - .5f;
t2.derived_vertex2.point.x = (t2.derived_vertex2.point.x + 1.f) * fw_over_2 - .5f;
t2.derived_vertex2.point.y = (t2.derived_vertex2.point.y + 1.f) * fh_over_2 - .5f;
t2.derived_vertex3.point.x = (t2.derived_vertex3.point.x + 1.f) * fw_over_2 - .5f;
t2.derived_vertex3.point.y = (t2.derived_vertex3.point.y + 1.f) * fh_over_2 - .5f;
_draw_cropped_triangle(triangle, t2);
}
}
}
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