1. 題目：Implement Gouraud Shading or Phong Shading based on hw3
1.1. Goal
You are to write a program to read a set of commands from file and display result on screen.
1.2. Commands
大部分與《數媒筆記整理3》中的命令相同，這裏只貼出新的：
- object [filename] R G B Kd Ks N: Load a 3d model file, apply current modeling transform to the object, (R, G, B) is the Material Color of 3D Model, Kd, Ks, N is Constants for Lighting Equation.
- ambient Ka: The ambient light intensity for current 3d scene.
- background R G B: The background Color of window.
- light ID Ip X Y Z: create a point light source at Position(X, Y, Z), Ip is intensity of point light source, ID is an ID number (1~4) of light source, There are at most 4 light sources.
2. 分析
首先，像上次一樣讀數據文件，還有圖形文件，讀完圖形文件之後，可以取每個面的三個點計算每個面的正向向量之後可以獲得每個點的正向向量，方法是點遍歷所有面，所處在的面的正向向量加和的平均值；
之後計算每個點的I，按照公式：首先Ka就是第一種光，沒有Ia，之後第二種光fatt設置爲1，然後其他向量之間的計算應該沒有難點；
之後進行上次的那些轉換，變到SS空間，用zBuffer那些算法，首先全設爲背景色，之後遍歷每個點，看是否在一個面內（判斷一個點是否在所圍成的全部直線的左邊或者右邊），然後用轉換的座標，計算每個面的
plan function，求出A,B,C,D。
這樣遍歷屏幕，就會得到每個屏幕點的z值，之後與zBuffer比較，小於，就改zBuffer和cBuffer。
這一點的所在面的某一頂點的I乘以Object R,G,B，之後用drawdot()就可以畫出圖了。
3. 源碼
/* Calculate and get GRM, Mirror Matrix. */
void Observer(float x1, float x2, float x3, float x4, float x5, float x6, float x7, float x8, float x9, float x10) {
H = x8, y = x9, theta = x10;
int i, j;
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
GRM[i][j] = 0;
Mirror[i][j] = 0;
}
}
Mirror[0][0] = -1, Mirror[1][1] = 1, Mirror[2][2] = 1, Mirror[3][3] = 1;
float vt[3], vz[3], v1[3], v2[3], v3[3];
vt[0] = 0, vt[1] = 1, vt[2] = 0;
vz[0] = x4 - x1, vz[1] = x5 - x2, vz[2] = x6 - x3;
float length_of_vz = sqrt(vz[0] * vz[0] + vz[1] * vz[1] + vz[2] * vz[2]);
float length_of_vt = 1;
v3[0] = vz[0] / length_of_vz, v3[1] = vz[1] / length_of_vz, v3[2] = vz[2] / length_of_vz;
float length_of_v3 = 1;
v1[0] = vt[1] * vz[2] - vt[2] * vz[1], v1[1] = vt[2] * vz[0] - vt[0] * vz[1], v1[2] = vt[0] * vz[1] - vt[1] * vz[0];
float length_of_v1 = sqrt(v1[0] * v1[0] + v1[1] * v1[1] + v1[2] * v1[2]);
v1[0] = v1[0] / length_of_v1, v1[1] = v1[1] / length_of_v1, v1[2] = v1[2] / length_of_v1;
v2[0] = v3[1] * v1[2] - v3[2] * v1[1], v2[1] = v3[2] * v1[0] - v3[0] * v1[1], v2[2] = v3[0] * v1[1] - v3[1] * v1[0];
float length_of_v2 = sqrt(v2[0] * v2[0] + v2[1] * v2[1] + v2[2] * v2[2]);
v2[0] = v2[0] / length_of_v2, v2[1] = v2[1] / length_of_v2, v2[2] = v2[2] / length_of_v2;
GRM[0][0] = v1[0], GRM[0][1] = v1[1], GRM[0][2] = v1[2];
GRM[1][0] = v2[0], GRM[1][1] = v2[1], GRM[1][2] = v2[2];
GRM[2][0] = v3[0], GRM[2][1] = v3[1], GRM[2][2] = v3[2], GRM[3][3] = 1;
Eye_Translate(-x1, -x2, -x3);
Eye_Tilt(-x7);
}
/* 3D rendering pipeline, multiply PM, eye tilt, mirror, GRM, eye translate, translate. Then get the final vertex.*/
void Display() {
int i, j, k;
int l = 0;
float AR = 1;
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
PM[i][j] = 0;
}
}
PM[0][0] = 1;
PM[1][1] = AR;
PM[2][2] = y * tan((theta / 180.0 * 3.14159265 )) / (y - H);
PM[2][3] = H * y * tan((theta / 180.0 * 3.14159265 )) / (H - y);
PM[3][2] = tan((theta / 180.0 * 3.14159265 ));
for (i = 0 ; i < 600 ; i++) {
for (j = 0 ; j < 600 ; j++) {
zBuffer[i][j] = 12353093;
cBuffer[i][j].r = background_r;
cBuffer[i][j].g = background_g;
cBuffer[i][j].b = background_b;
}
}
/* L presents the number of objects. */
for (l = 0 ; l < number_of_read_object ; l++) {
for (i = 0 ; i < store_current_num_vertex[l] ; i++) {
for (j = 0 ; j < store_current_num_face[l] ; j++) {
if (number_of_vertex_in_one_face[l] == 3) {
if ((i == vertex_face[l][j][0]-1) || (i == vertex_face[l][j][1]-1) || (i == vertex_face[l][j][2]-1)) {
average_normal_vector_point[l][i].a += normal_vector_face[l][j].a;
average_normal_vector_point[l][i].b += normal_vector_face[l][j].b;
average_normal_vector_point[l][i].c += normal_vector_face[l][j].c;
counter_of_vertex_vector++;
}
}
else if (number_of_vertex_in_one_face[l] == 4) {
if ((i == vertex_face[l][j][0]-1) || (i == vertex_face[l][j][1]-1) || (i == vertex_face[l][j][2]-1) || (i == vertex_face[l][j][3]-1)) {
average_normal_vector_point[l][i].a += normal_vector_face[l][j].a;
average_normal_vector_point[l][i].b += normal_vector_face[l][j].b;
average_normal_vector_point[l][i].c += normal_vector_face[l][j].c;
counter_of_vertex_vector++;
}
}
}
average_normal_vector_point[l][i].a /= counter_of_vertex_vector;
average_normal_vector_point[l][i].b /= counter_of_vertex_vector;
average_normal_vector_point[l][i].c /= counter_of_vertex_vector;
float Length_Of_N = sqrt(average_normal_vector_point[l][i].a * average_normal_vector_point[l][i].a + average_normal_vector_point[l][i].b * average_normal_vector_point[l][i].b + average_normal_vector_point[l][i].c * average_normal_vector_point[l][i].c);
/* N vector */
average_normal_vector_point[l][i].a /= Length_Of_N;
average_normal_vector_point[l][i].b /= Length_Of_N;
average_normal_vector_point[l][i].c /= Length_Of_N;
counter_of_vertex_vector = 0;
/* L vector */
I_Value[l][i] = Ka;
for (k = 0 ; k < number_of_light ; k++) {
float px, py, pz;
px = vertex_point[l][i][0] - light_vector[k].x;
py = vertex_point[l][i][1] - light_vector[k].y;
pz = vertex_point[l][i][2] - light_vector[k].z;
float Length_Of_L = sqrt(px*px + py*py + pz*pz);
px /= Length_Of_L, py /= Length_Of_L, pz /= Length_Of_L;
/* N*L */
float Diffuse_Value = ol[l].Kd * light_vector[k].ip * (px * average_normal_vector_point[l][i].a + py * average_normal_vector_point[l][i].b + pz * average_normal_vector_point[l][i].c);
if (Diffuse_Value < 0) {
Diffuse_Value = 0;
}
I_Value[l][i] += Diffuse_Value;
}
for (k = 0 ; k < number_of_light ; k++) {
float a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, g = 0, h = 0, m = 0;
/* L vector */
a = light_vector[k].x - vertex_point[l][i][0];
b = light_vector[k].y - vertex_point[l][i][1];
c = light_vector[k].z - vertex_point[l][i][2];
/* V vector */
d = Px - vertex_point[l][i][0];
e = Py - vertex_point[l][i][1];
f = Pz - vertex_point[l][i][2];
/* H vector */
g = a + d, h = b + e, m = c + f;
float Length_Of_H = sqrt(g*g + h*h + m*m);
g /= Length_Of_H, h /= Length_Of_H, m /= Length_Of_H;
double temp = g * average_normal_vector_point[l][i].a + h * average_normal_vector_point[l][i].b + m * average_normal_vector_point[l][i].c;
if (temp < 0) {
temp = 0;
}
double Specular_Value = ol[l].Ks * light_vector[k].ip * pow(temp, ol[l].N);
I_Value[l][i] += Specular_Value;
}
if (IMAX <= I_Value[l][i]) {
IMAX = I_Value[l][i];
}
}
cout << "WTF!" << endl << endl;
if (IMAX <= 1) {
IMAX = 1;
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix_Copy[i][j] = 0;
}
}
/* PM * Tilt */
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
for (k = 0 ; k < 4 ; k++) {
Current_Matrix_Copy[i][j] += PM[i][k] * Eye_Tilt_Matrix[k][j];
}
}
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix[l][i][j] = Current_Matrix_Copy[i][j];
Current_Matrix_Copy[i][j] = 0;
}
}
/* Mirror*/
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
for (k = 0 ; k < 4 ; k++) {
Current_Matrix_Copy[i][j] += Current_Matrix[l][i][k] * Mirror[k][j];
}
}
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix[l][i][j] = Current_Matrix_Copy[i][j];
Current_Matrix_Copy[i][j] = 0;
}
}
/* *GRM */
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
for (k = 0 ; k < 4 ; k++) {
Current_Matrix_Copy[i][j] += Current_Matrix[l][i][k] * GRM[k][j];
}
}
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix[l][i][j] = Current_Matrix_Copy[i][j];
Current_Matrix_Copy[i][j] = 0;
}
}
/* *Eye_Translate*/
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
for (k = 0 ; k < 4 ; k++) {
Current_Matrix_Copy[i][j] += Current_Matrix[l][i][k] * Eye_Translate_Matrix[k][j];
}
}
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix[l][i][j] = Current_Matrix_Copy[i][j];
Current_Matrix_Copy[i][j] = 0;
}
}
/* *Translate_Matrix */
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
for (k = 0 ; k < 4 ; k++) {
Current_Matrix_Copy[i][j] += Current_Matrix[l][i][k] * Translate_Matrix[l][k][j];
}
}
}
for (i = 0 ; i < 4 ; i++) {
for (j = 0 ; j < 4 ; j++) {
Current_Matrix[l][i][j] = Current_Matrix_Copy[i][j];
Current_Matrix_Copy[i][j] = 0;
}
}
for (i = 0 ; i < store_current_num_vertex[l] ; i++) {
for (j = 0 ; j < 4 ; j++) {
float temp = 0;
for (k = 0 ; k < 4 ; k++) {
temp += Current_Matrix[l][j][k] * vertex_point[l][i][k];
}
result_vertex_point[i][j] = temp;
}
}
for (i = 0 ; i < store_current_num_vertex[l] ; i++) {
float divide = result_vertex_point[i][3];
result_vertex_point[i][0] = result_vertex_point[i][0] / divide;
result_vertex_point[i][1] = result_vertex_point[i][1] / divide;
result_vertex_point[i][2] = result_vertex_point[i][2] / divide;
result_vertex_point[i][3] = result_vertex_point[i][3] / divide;
result_vertex_point[i][0] *= (Vr - Vl) / 2;
result_vertex_point[i][0] += (Vr - Vl) / 2;
result_vertex_point[i][1] *= (Vt - Vb) / 2;
result_vertex_point[i][1] += (Vt - Vb) / 2;
}
for (i = 0 ; i < store_current_num_face[l] ; i++) {
float x1, x2, x3, y1, y2, y3, z1, z2, z3, x4, y4, z4, z;
float a[3], b[3], c[3];
x1 = result_vertex_point[vertex_face[l][i][0]-1][0], y1 = result_vertex_point[vertex_face[l][i][0]-1][1], z1 = result_vertex_point[vertex_face[l][i][0]-1][2];
x2 = result_vertex_point[vertex_face[l][i][1]-1][0], y2 = result_vertex_point[vertex_face[l][i][1]-1][1], z2 = result_vertex_point[vertex_face[l][i][1]-1][2];
x3 = result_vertex_point[vertex_face[l][i][2]-1][0], y3 = result_vertex_point[vertex_face[l][i][2]-1][1], z3 = result_vertex_point[vertex_face[l][i][2]-1][2];
a[0] = x2 - x1, a[1] = y2 - y1, a[2] = z2 - z1;
b[0] = x3 - x2, b[1] = y3 - y2, b[2] = z3 - z2;
c[0] = a[1]*b[2] - a[2]*b[1], c[1] = a[2]*b[0] - a[0]*b[2], c[2] = a[0]*b[1] - a[1]*b[0];
pe[i].A = c[0], pe[i].B = c[1], pe[i].C = c[2], pe[i].D = -(c[0] * x1 + c[1] * y1 + c[2] * z1);
for (j = 0 ; j < 600 ; j++) {
for (k = 0 ; k < 600 ; k++) {
if (number_of_vertex_in_one_face[l] == 3) {
if ((((j - x1)*(y2 - y1) - (x2 - x1)*(k - y1)) <= 0) && (((j - x2)*(y3 - y2) - (x3 - x2)*(k - y2)) <= 0) && (((j - x3)*(y1 - y3) - (x1 - x3)*(k - y3)) <= 0) || (((j - x1)*(y2 - y1) - (x2 - x1)*(k - y1)) >= 0) && (((j - x2)*(y3 - y2) - (x3 - x2)*(k - y2)) >= 0) && (((j - x3)*(y1 - y3) - (x1 - x3)*(k - y3)) >= 0)) {
z = -(pe[i].A*j + pe[i].B*k + pe[i].D) / pe[i].C;
if (z < zBuffer[j][k]) {
zBuffer[j][k] = z;
cBuffer[j][k].r = ol[l].r*(I_Value[l][vertex_face[l][i][0]-1] + I_Value[l][vertex_face[l][i][1]-1] + I_Value[l][vertex_face[l][i][2]-1])/(3*IMAX);
cBuffer[j][k].g = ol[l].g;
cBuffer[j][k].b = ol[l].b;
}
}
}
else if (number_of_vertex_in_one_face[l] == 4) {
x4 = result_vertex_point[vertex_face[l][i][3]-1][0], y4 = result_vertex_point[vertex_face[l][i][3]-1][1], z4 = result_vertex_point[vertex_face[l][i][3]-1][2];
if ((((j - x1)*(y2 - y1) - (x2 - x1)*(k - y1)) <= 0) && (((j - x2)*(y3 - y2) - (x3 - x2)*(k - y2)) <= 0) && (((j - x3)*(y4 - y3) - (x4 - x3)*(k - y3)) <= 0) && (((j - x4)*(y1 - y4) - (x1 - x4)*(k - y4)) <= 0) || (((j - x1)*(y2 - y1) - (x2 - x1)*(k - y1)) >= 0) && (((j - x2)*(y3 - y2) - (x3 - x2)*(k - y2)) >= 0) && (((j - x3)*(y4 - y3) - (x4 - x3)*(k - y3)) >= 0) && (((j - x4)*(y1 - y4) - (x1 - x4)*(k - y4)) >= 0)) {
z = -(pe[i].A*j + pe[i].B*k + pe[i].D) / pe[i].C;
if (z < zBuffer[j][k]) {
cBuffer[j][k].r = ol[l].r*(I_Value[l][vertex_face[l][i][0]-1] + I_Value[l][vertex_face[l][i][1]-1] + I_Value[l][vertex_face[l][i][2]-1] + I_Value[l][vertex_face[l][i][3]-1])/(4*IMAX);
cBuffer[j][k].g = ol[l].g;
cBuffer[j][k].b = ol[l].b;
zBuffer[j][k] = z;
}
}
}
}
}
}
for (i = 0 ; i < 600 ; i++) {
for (j = 0 ; j < 600 ; j++) {
drawDot(i, j, cBuffer[i][j].r, cBuffer[i][j].g, cBuffer[i][j].b);
}
}
glFlush();
}
}