SoftwareRasterizer/camera.cpp at master · KENC1999/SoftwareRasterizer · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
#include <cmath>
#include<iostream>
#include <limits>
#include <cstdlib>
#include "camera.h"

#define inf 1e4
using namespace std;
fstream f("txt_out.txt", ios::out);


camera::camera(void) {
	eye_pos << 0, 0, 3, 1;
	center << 0, 0, 0, 1;
	//eye_direction << 0-eye_pos(0), 0 - eye_pos(1), 0 - eye_pos(2), 0;
	up << 0, 1, 0;
	eye_direction.normalize();
	up.normalize();
}

void camera::lookat() {//相机变换，此部分推导均见笔记
	//Vector4d center3 = center / center(3);
	Vector3d minus_g = (eye_pos-center).normalized().head(3);
	Vector3d gxt = up.cross(minus_g).normalized();//让视线始终看向中心，这样令up=(0,0,1)就可以算出3个向量，注意叉乘方向
	Vector3d t = minus_g.cross(gxt).normalized();
	Vector3d eye_pos3 = eye_pos.head(3);
	//cout << t <<endl<<minus_g<<endl<<gxt<< endl;
	Matrix4d R = MatrixXd::Identity(4, 4);
	Matrix4d T = MatrixXd::Identity(4, 4);
	//cout << R << endl << T << endl << ModelView << endl;
	for (int i = 0; i < 3; i++) {
		R(0, i) = gxt(i);
		R(1, i) = t(i);
		R(2, i) = minus_g(i);
		T(i, 3) = -eye_pos3(i);
	}
	ModelView = R * T;
	//	cout << R << endl << T << endl << ModelView << endl;
}

void camera::viewtrans(int x, int y, int width, int height, int depth=2) {//视口变换，映射到屏幕空间
	ViewPort(0, 0) = width / 2.f;
	ViewPort(0, 3) = x + width / 2.f;
	ViewPort(1, 1) = height / 2.f;
	ViewPort(1, 3) = y + height / 2.f;
	ViewPort(2, 2) = depth / 2.f;
	ViewPort(2, 3) = depth / 2.f;
}

void camera::viewproject1(double n,double f) {//透视变换，只根据远近做缩放
	//Persp2ortho(0, 0) = -n;
	//Persp2ortho(1, 1) = -n;
	//Persp2ortho(2, 2) = n + f;
	//Persp2ortho(2, 3) = -n*f;
	//Persp2ortho(3, 2) = 1;
	double len = (eye_pos - center).norm();
	if (len != 0) {
		Persp2ortho(0, 0) = 3.f / len;
		Persp2ortho(1, 1) = 3.f / len;
	}
	else {
		Persp2ortho(0, 0) = 0;
		Persp2ortho(1, 1) = 0;
		Persp2ortho(2, 2) = 0;
	}
}

void camera::viewproject2(double r, double l, double t, double b, double nn, double ff) {//将所有顶点移到-1，1的正方体中，未使用
	//double r = *max_element(x_prime.begin(), x_prime.end());
	//double l = *min_element(x_prime.begin(), x_prime.end());
	//double t = *max_element(y_prime.begin(), y_prime.end());
	//double b = *min_element(y_prime.begin(), y_prime.end());
	//double nn = *max_element(z_prime.begin(), z_prime.end());
	//double ff = *min_element(z_prime.begin(), z_prime.end());
	Ortho(0, 0) = (r != l) ? 2 / (r - l) : 0;//为平面直接放到中心
	Ortho(0, 3) = (r != l) ? -(r + l) / (r - l) : 0;
	Ortho(1, 1) = (t != b) ? 2 / (t - b) : 0;
	Ortho(1, 3) = (t != b) ? -(t + b) / (t - b) : 0;
	Ortho(2, 2) = (nn != ff) ? 2 / (nn - ff) : 0;
	Ortho(2, 3) = (nn != ff) ? -(nn + ff) / (nn - ff) : 0;
}

void camera::vertex_change(Model *model, vector<FaceInfo, aligned_allocator<FaceInfo>>& AllFace,int width,int height) {
	AllFace.clear();
	lookat();
	viewproject1(1,10);
	for (int i = 0; i < model->nfaces(); i++) {
		//cout << i << endl;

		Matrix3d o_vt = MatrixXd::Zero(3, 3);
		for (int j = 0; j < 3; j++) {//背面剔除，先判断面法线和视线夹角是否小于90度，若大于说明该面看不见直接跳过
			Vec3f worldc = model->vert(i, j);
			o_vt.col(j) << worldc.x, worldc.y, worldc.z;
		}
		Vector3d face_norm = (o_vt.col(0) - o_vt.col(1)).cross(o_vt.col(0) - o_vt.col(2)).normalized();
		Vector3d eye_dir = (eye_pos - center).normalized().head(3);
		if (face_norm.dot(eye_dir) <= 0)
			continue;

		FaceInfo nowface;
		nowface.nface = i;
		bool flag = true;
		for (int j = 0; j < 3; j++) {
			Vec3f vt=model->vert(i, j);
			Vector4d hc_vt;
			hc_vt << vt.x ,vt.y , vt.z , 1;
			hc_vt = ModelView * hc_vt;//变换到相机坐标系下
			if (hc_vt(2) >= 0) {
				flag = false;
				break;
			}//这个面存在在相机背后的点(z>0)，那么就不画这个面了
			hc_vt = Persp2ortho*hc_vt;//透视变换
			hc_vt = hc_vt / hc_vt(3);//齐次坐标标准化
			nowface.vt[j] = hc_vt;
			nowface.uv[j] = model->uv(i, j);
			//nowface.uv[j] << model->uv(i, j).x, model->uv(i, j).y;
			Vec3f normal = model->normal(i, j);//法线也会变，一会儿再改
			nowface.normal[j] << normal.x, normal.y, normal.z, 0;

		}
		//cout << flag << endl;
		if (flag) {
			AllFace.push_back(nowface);	//将该面加入待绘制面的序列中
			/*
			for (int j = 0; j < 3; j++) {
				//cout << nowface.vt[j] << endl;
				if (nowface.vt[j](0) < l)
					l = nowface.vt[j](0);
				else if (nowface.vt[j](0) > r)
					r = nowface.vt[j](0);
				if (nowface.vt[j](1) < b)
					b = nowface.vt[j](1);
				else if (nowface.vt[j](1) > t)
					t = nowface.vt[j](1);
				if (nowface.vt[j](2) < ff)
					ff = nowface.vt[j](2);
				else if (nowface.vt[j](2) > nn)
					nn = nowface.vt[j](2);
			}
			*/
		}
	}

	//viewproject2(r, l, t, b, nn, ff);
	viewtrans(width/8, height/8, 3*width/4, 3*height/4, 255);
	//Matrix4d n_trans = (ViewPort * Persp2ortho*ModelView);
	Matrix4d n_trans = (ViewPort * Persp2ortho*ModelView).inverse().transpose();
	for (int i = 0; i < AllFace.size(); i++) {//计算视口变换后的顶点坐标、法向量
		for (int j = 0; j < 3; j++) {
			AllFace[i].vt[j] = ViewPort*AllFace[i].vt[j];
			AllFace[i].normal[j] = (n_trans *AllFace[i].normal[j]).normalized();
		}
	}
}

void camera::cam_change(int zoom , int rot1 , int rot2) {
	if (!zoom&&!rot1&&!rot2)
		return;
	if (zoom == 1) {
		if ((center - eye_pos).norm() >= 1+0.25) {
			Vector4d dir = (center - eye_pos).normalized();
			eye_pos = eye_pos + 0.25*dir;//往中心平移0.1个单位向量长度
		}
		return;
	}
	else if (zoom == 2) {
		if ((center - eye_pos).norm() <= 8-0.25) {
			Vector4d dir = (center - eye_pos).normalized();
			eye_pos = eye_pos - 0.25*dir;//向外平移0.1个单位向量长度
		}
		return;
	}
	Matrix4d R1 = MatrixXd::Identity(4, 4), R2 = MatrixXd::Identity(4, 4);
	if (rot1) {//相机绕y轴旋转
		//Vector4d v = eye_pos - center;
		double alpha = M_PI / 10;
		if (rot1 == 2)
			alpha = -alpha;
		R1(0, 0) = cos(alpha); R1(0, 2) = sin(alpha); R1(2, 0) = -sin(alpha); R1(2, 2) = cos(alpha);
		//R1 = T2 * R1*T1;
	}
	if (rot2) {//相机绕中心垂直xz平面旋转（先转到z轴，再在yz面上转，最后再从z轴转回）
		double alpha = -M_PI / 10;
		Matrix4d T1 = Matrix4d::Identity(4, 4),T2= Matrix4d::Identity(4, 4);
		//f << eye_pos(0) / sqrt(pow(eye_pos(0), 2) + pow(eye_pos(2), 2)) << endl;
		double cosy= sqrt(pow(eye_pos(0), 2) + pow(eye_pos(2), 2))/ sqrt(pow(eye_pos(0), 2) + pow(eye_pos(1), 2) + pow(eye_pos(2), 2));//与y轴夹角，太小就不能转了
		bool flag = true;
		if (rot2 == 1) {
			if (eye_pos(1) > 0 && cosy <= cos(0.95*M_PI / 2 + alpha))
				flag = false;
		}
		else {
			alpha = -alpha;
			if (eye_pos(1) < 0 && cosy <= cos(0.95*M_PI / 2 - alpha))
				flag = false;
		}
		if (flag) {
			double beta = asin(eye_pos(0) / sqrt(pow(eye_pos(0), 2) + pow(eye_pos(2), 2)));
			beta = -beta;
			f << beta << endl << endl;
			if (eye_pos(2) < 0 && eye_pos(0) >= 0)
				beta = M_PI - beta;
			else if (eye_pos(2) < 0 && eye_pos(0) < 0)
				beta = -(M_PI + beta);
			T1(0, 0) = cos(beta); T1(0, 2) = sin(beta); T1(2, 0) = -sin(beta); T1(2, 2) = cos(beta);

			T2(1, 1) = cos(alpha); T2(1, 2) = -sin(alpha); T2(2, 1) = sin(alpha); T2(2, 2) = cos(alpha);
			R2 = T1.transpose()*T2*T1;
		}
	}
	//f << R2 << endl << endl;
	eye_pos = R2*R1*eye_pos;
}