243 lines
7.0 KiB
C++
243 lines
7.0 KiB
C++
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// clang-format off
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//
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// Created by goksu on 4/6/19.
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//
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#include <algorithm>
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#include <vector>
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#include "rasterizer.hpp"
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#include <opencv2/opencv.hpp>
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#include <math.h>
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rst::pos_buf_id rst::rasterizer::load_positions(const std::vector<Eigen::Vector3f> &positions)
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{
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auto id = get_next_id();
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pos_buf.emplace(id, positions);
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return {id};
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}
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rst::ind_buf_id rst::rasterizer::load_indices(const std::vector<Eigen::Vector3i> &indices)
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{
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auto id = get_next_id();
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ind_buf.emplace(id, indices);
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return {id};
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}
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rst::col_buf_id rst::rasterizer::load_colors(const std::vector<Eigen::Vector3f> &cols)
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{
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auto id = get_next_id();
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col_buf.emplace(id, cols);
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return {id};
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}
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auto to_vec4(const Eigen::Vector3f& v3, float w = 1.0f)
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{
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return Vector4f(v3.x(), v3.y(), v3.z(), w);
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}
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static bool insideTriangle(int x, int y, const Vector3f* _v)
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{
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//side vector
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Eigen::Vector2f side1;
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side1 << _v[0].x()-_v[1].x(),_v[0].y()-_v[1].y();
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Eigen::Vector2f side2;
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side2 << _v[2].x()-_v[0].x(),_v[2].y()-_v[0].y();
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Eigen::Vector2f side3;
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side3 << _v[1].x()-_v[2].x(),_v[1].y()-_v[2].y();
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//vector between testPoint and vertex of triangle
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Eigen::Vector2f po1;
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po1 << x-_v[0].x(),y-_v[0].y();
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Eigen::Vector2f po2;
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po2 << x-_v[1].x(),y-_v[1].y();
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Eigen::Vector2f po3;
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po3 << x-_v[2].x(),y-_v[2].y();
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//cross product
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float z1 = side1.x()*po1.y()-side1.y()*po1.x();
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float z2 = side2.x()*po2.y()-side2.y()*po2.x();
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float z3 = side3.x()*po3.y()-side3.y()*po3.x();
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//if they have the same character,the point is inside the triangle
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if((z1<0 && z2<0 && z3<0 )||(z1>0 && z2>0 && z3>0))
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{
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return true;
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}
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else
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{
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return false;
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}
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// TODO : Implement this function to check if the point (x, y) is inside the triangle represented by _v[0], _v[1], _v[2]
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}
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static std::tuple<float, float, float> computeBarycentric2D(float x, float y, const Vector3f* v)
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{
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float c1 = (x*(v[1].y() - v[2].y()) + (v[2].x() - v[1].x())*y + v[1].x()*v[2].y() - v[2].x()*v[1].y()) / (v[0].x()*(v[1].y() - v[2].y()) + (v[2].x() - v[1].x())*v[0].y() + v[1].x()*v[2].y() - v[2].x()*v[1].y());
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float c2 = (x*(v[2].y() - v[0].y()) + (v[0].x() - v[2].x())*y + v[2].x()*v[0].y() - v[0].x()*v[2].y()) / (v[1].x()*(v[2].y() - v[0].y()) + (v[0].x() - v[2].x())*v[1].y() + v[2].x()*v[0].y() - v[0].x()*v[2].y());
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float c3 = (x*(v[0].y() - v[1].y()) + (v[1].x() - v[0].x())*y + v[0].x()*v[1].y() - v[1].x()*v[0].y()) / (v[2].x()*(v[0].y() - v[1].y()) + (v[1].x() - v[0].x())*v[2].y() + v[0].x()*v[1].y() - v[1].x()*v[0].y());
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return {c1,c2,c3};
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}
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void rst::rasterizer::draw(pos_buf_id pos_buffer, ind_buf_id ind_buffer, col_buf_id col_buffer, Primitive type)
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{
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auto& buf = pos_buf[pos_buffer.pos_id];
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auto& ind = ind_buf[ind_buffer.ind_id];
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auto& col = col_buf[col_buffer.col_id];
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float f1 = (50 - 0.1) / 2.0;
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float f2 = (50 + 0.1) / 2.0;
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Eigen::Matrix4f mvp = projection * view * model;
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for (auto& i : ind)
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{
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Triangle t;
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Eigen::Vector4f v[] = {
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mvp * to_vec4(buf[i[0]], 1.0f),
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mvp * to_vec4(buf[i[1]], 1.0f),
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mvp * to_vec4(buf[i[2]], 1.0f)
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};
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//Homogeneous division
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for (auto& vec : v) {
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vec /= vec.w();
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}
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//Viewport transformation
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for (auto & vert : v)
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{
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vert.x() = 0.5*width*(vert.x()+1.0);
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vert.y() = 0.5*height*(vert.y()+1.0);
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vert.z() = vert.z() * f1 + f2;
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}
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for (int i = 0; i < 3; ++i)
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{
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t.setVertex(i, v[i].head<3>());
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t.setVertex(i, v[i].head<3>());
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t.setVertex(i, v[i].head<3>());
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}
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auto col_x = col[i[0]];
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auto col_y = col[i[1]];
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auto col_z = col[i[2]];
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t.setColor(0, col_x[0], col_x[1], col_x[2]);
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t.setColor(1, col_y[0], col_y[1], col_y[2]);
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t.setColor(2, col_z[0], col_z[1], col_z[2]);
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rasterize_triangle(t);
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}
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}
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//Screen space rasterization
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void rst::rasterizer::rasterize_triangle(const Triangle& t) {
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auto v = t.toVector4();
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//bounding box
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float max_x= std::max(v[0].x(),std::max(v[1].x(),v[2].x()));
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float min_x= std::min(v[0].x(),std::min(v[1].x(),v[2].x()));
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float max_y= std::max(v[0].y(),std::max(v[1].y(),v[2].y()));
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float min_y= std::min(v[0].y(),std::min(v[1].y(),v[2].y()));
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for(int x =min_x;x <= max_x;x++)
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{
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for(int y = min_y;y <= max_y;y++)
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{
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if(insideTriangle(x,y,t.v))
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{
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//以下是计算插值的内容，暂时看不懂,先抄别人博客补全
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//最小深度，默认是无穷远
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float min_depth = FLT_MAX;
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//如果在三角形内部，计算当前深度,得到当前最小深度
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auto tup = computeBarycentric2D(x, y, t.v);
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float alpha , beta, gamma;
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std::tie(alpha, beta, gamma) = tup;
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float w_reciprocal = 1.0 / (alpha / v[0].w() + beta / v[1].w() + gamma / v[2].w());
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float z_interpolated = alpha * v[0].z() / v[0].w() + beta * v[1].z() / v[1].w() + gamma * v[2].z() / v[2].w();
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z_interpolated *= w_reciprocal;
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//如果x,y所在点的深度小于z-buffer的深度，
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if (z_interpolated<depth_buf[get_index(x,y)])
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{
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//获得最上层应该渲染的颜色
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Vector3f color = t.getColor();
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Vector3f point;
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point << x, y, min_depth;
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//更新深度
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depth_buf[get_index(x, y)] = z_interpolated;
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//更新所在点的颜色
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set_pixel(point, color);
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}
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}
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}
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}
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// TODO : Find out the bounding box of current triangle.
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// iterate through the pixel and find if the current pixel is inside the triangle
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// If so, use the following code to get the interpolated z value.
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//
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//
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//
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//z_interpolated *= w_reciprocal;
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// TODO : set the current pixel (use the set_pixel function) to the color of the triangle (use getColor function) if it should be painted.
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}
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void rst::rasterizer::set_model(const Eigen::Matrix4f& m)
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{
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model = m;
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}
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void rst::rasterizer::set_view(const Eigen::Matrix4f& v)
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{
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view = v;
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}
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void rst::rasterizer::set_projection(const Eigen::Matrix4f& p)
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{
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projection = p;
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}
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void rst::rasterizer::clear(rst::Buffers buff)
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{
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if ((buff & rst::Buffers::Color) == rst::Buffers::Color)
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{
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std::fill(frame_buf.begin(), frame_buf.end(), Eigen::Vector3f{0, 0, 0});
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}
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if ((buff & rst::Buffers::Depth) == rst::Buffers::Depth)
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{
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std::fill(depth_buf.begin(), depth_buf.end(), std::numeric_limits<float>::infinity());
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}
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}
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rst::rasterizer::rasterizer(int w, int h) : width(w), height(h)
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{
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frame_buf.resize(w * h);
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depth_buf.resize(w * h);
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}
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int rst::rasterizer::get_index(int x, int y)
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{
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return (height-1-y)*width + x;
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}
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void rst::rasterizer::set_pixel(const Eigen::Vector3f& point, const Eigen::Vector3f& color)
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{
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//old index: auto ind = point.y() + point.x() * width;
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auto ind = (height-1-point.y())*width + point.x();
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frame_buf[ind] = color;
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}
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// clang-format on
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