add dice project

project/dice/Makefile

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+all:
+	gcc dice.c -o dice -lm
+
+clean:
+	rm dice

project/dice/README.md

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+# dice
+
+https://www.zhihu.com/question/386347847/answer/2576561977
+

project/dice/dice.c

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+#include <stdlib.h>
+#include <stdio.h>
+#include <memory.h>
+#include <math.h>
+#include <unistd.h>
+
+#define pi 3.14159265358979323846
+#define c 3
+#define screen_width 50
+#define screen_height 25
+
+float cube[6][4][3] = {
+    {{-0.5, -0.5, 0.5},  {0.5, -0.5, 0.5},   {-0.5, 0.5, 0.5},  {0.0, 0.0, 1.0}},
+    {{-0.5, -0.5, 0.5},  {-0.5, -0.5, -0.5}, {-0.5, 0.5, 0.5},  {-1.0, 0.0, 0.0}},
+    {{-0.5, -0.5, 0.5},  {-0.5, -0.5, -0.5}, {0.5, -0.5, 0.5},  {0.0, -1.0, 0.0}},
+    {{-0.5, 0.5, 0.5},   {0.5, 0.5, 0.5},    {-0.5, 0.5, -0.5}, {0.0, 1.0, 0.0}},
+    {{0.5, -0.5, 0.5},   {0.5, -0.5, -0.5},  {0.5, 0.5, 0.5},   {1.0, 0.0, 0.0}},
+    {{-0.5, -0.5, -0.5}, {0.5, -0.5, -0.5},  {-0.5, 0.5, -0.5}, {0.0, 0.0, -1.0}}
+};
+
+int face[6][3][3] = {
+    {{0, 0, 0}, {0, 1, 0}, {0, 0, 0}},
+    {{0, 0, 1}, {0, 0, 0}, {1, 0, 0}},
+    {{0, 0, 1}, {0, 1, 0}, {1, 0, 0}},
+    {{1, 0, 1}, {0, 0, 0}, {1, 0, 1}},
+    {{1, 0, 1}, {0, 1, 0}, {1, 0, 1}},
+    {{1, 0, 1}, {1, 0, 1}, {1, 0, 1}}
+};
+
+int judgeFace(int ID, float x, float y)
+{
+    return face[ID][(int)(3.f * y)][(int)(3.f * x)];
+}
+
+void init()
+{
+    for (int i = 0; i < 6; i++)
+    {
+        for (int j = 0; j < 4; j++)
+        {
+            float x = cube[i][j][0];
+            float y = cube[i][j][1];
+            float z = cube[i][j][2];
+
+            cube[i][j][0] = (sqrt(3) / 6.f + 0.5) * x - sqrt(3) / 3.f * y + (-0.5 + sqrt(3) / 6.f) * z;
+            cube[i][j][1] = (sqrt(3) / 3.f) * x + (sqrt(3) / 3.f) * y + (sqrt(3) / 3.f) * z;
+            cube[i][j][2] = (-0.5 + sqrt(3) / 6.f) * x + (-sqrt(3) / 3.f) * y + (sqrt(3) / 6.f + 0.5) * z;
+        }
+    }
+}
+
+void renderFrame()
+{
+    init();
+    double time = 0;
+    while (1)
+    {
+        time = time + 0.01;
+        float z_buffer[screen_height + 1][screen_width + 1];
+
+        for (int i = 0; i <= screen_height; i++)
+            for (int j = 0; j <= screen_width; j++)
+                z_buffer[i][j] = -100;
+
+        char output[screen_height + 1][screen_width + 1];
+        memset(output, ' ', sizeof(output));
+
+        for (int i = 0; i < 6; i++)
+        {
+            for (float u = 0.f; u < 1.f; u = u + 0.01)
+            {
+                for (float v = 0.f; v < 1.f; v = v + 0.01)
+                {
+                    float m_x = (cube[i][1][0] - cube[i][0][0]);
+                    float m_y = (cube[i][1][1] - cube[i][0][1]);
+                    float m_z = (cube[i][1][2] - cube[i][0][2]);
+
+                    float n_x = (cube[i][2][0] - cube[i][0][0]);
+                    float n_y = (cube[i][2][1] - cube[i][0][1]);
+                    float n_z = (cube[i][2][2] - cube[i][0][2]);
+
+                    float x = m_x * u + n_x * v + cube[i][0][0];
+                    float y = m_y * u + n_y * v + cube[i][0][1];
+                    float z = m_z * u + n_z * v + cube[i][0][2];
+
+                    float rotation_x = cos(time) * x - sin(time) * z;
+                    float rotation_y = y;
+                    float rotation_z = sin(time) * x + cos(time) * z;
+
+                    float normal_x = (cube[i][3][0]) * cos(time) - sin(time) * (cube[i][3][2]);
+                    float normal_y = cube[i][3][1];
+                    float normal_z = (cube[i][3][0]) * sin(time) + cos(time) * (cube[i][3][2]);
+
+                    int screen_x = (rotation_x / (1 - rotation_z / c) + 1.f) / 2 * screen_width;
+                    int screen_y = (rotation_y / (1 - rotation_z / c) + 1.f) / 2 * screen_height;
+                    float screen_z = rotation_z / (1 - rotation_z / c);
+
+                    float L = normal_z;
+                    if (L > 0)
+                    {
+                        if (z_buffer[screen_y][screen_x] < screen_z)
+                        {
+                            z_buffer[screen_y][screen_x] = screen_z;
+                            if (judgeFace(i, u, v) == 1)
+                            {
+                                float tempu = u - (float)((int)(u * 3.f)) * 1.f / 3.f;
+                                float tempv = v - (float)((int)(v * 3.f)) * 1.f / 3.f;
+                                if ((tempu - 1.f / 6.f) * (tempu - 1.f / 6.f) + (tempv - 1.f / 6.f) * (tempv - 1.f / 6.f) <= 1.f / 36.f)
+                                {
+                                    L = 0;
+                                }
+                                else
+                                    L = (L + 0.1) * sqrt(2);
+                            }
+                            else
+                                L = (L + 0.1) * sqrt(2);
+                            int luminance_index = L * 8;
+                            if (luminance_index > 11)
+                                luminance_index = 11;
+                            output[screen_y][screen_x] = ".,-~:;=!*#$@"[luminance_index];
+                        }
+                    }
+                    else if (z_buffer[screen_y][screen_x] < screen_z)
+                        z_buffer[screen_y][screen_x] = screen_z;
+                }
+            }
+        }
+        for (int j = screen_height; j >= 0; j--)
+        {
+            for (int i = 0; i <= screen_width; i++)
+            {
+                putchar(output[j][i]);
+            }
+            putchar('\n');
+        }
+        usleep(15000);
+        printf("\x1b[26A");
+    }
+}
+
+int main()
+{
+    renderFrame();
+    return 0;
+}