rotating cube

rot.c

#include <TFT_eSPI.h>
#include <SPI.h>

TFT_eSPI tft = TFT_eSPI();

// 3D coordinates for cube vertices
const float vertices[8][3] = {
    {-1, -1, -1}, {1, -1, -1}, {1, 1, -1}, {-1, 1, -1},
    {-1, -1, 1}, {1, -1, 1}, {1, 1, 1}, {-1, 1, 1}
};

// Edges connecting vertices
const uint8_t edges[12][2] = {
    {0,1}, {1,2}, {2,3}, {3,0},
    {4,5}, {5,6}, {6,7}, {7,4},
    {0,4}, {1,5}, {2,6}, {3,7}
};

// Display dimensions
const int centerX = 120;  // Half of 240
const int centerY = 135;  // Half of 270
const float scale = 40.0;

float angleX = 0;
float angleY = 0;
float angleZ = 0;

void setup() {
    tft.init();
    tft.setRotation(0);
    tft.fillScreen(TFT_BLACK);
}

// Rotate point around X axis
void rotateX(float& y, float& z, float angle) {
    float y1 = y * cos(angle) - z * sin(angle);
    float z1 = y * sin(angle) + z * cos(angle);
    y = y1;
    z = z1;
}

// Rotate point around Y axis
void rotateY(float& x, float& z, float angle) {
    float x1 = x * cos(angle) - z * sin(angle);
    float z1 = x * sin(angle) + z * cos(angle);
    x = x1;
    z = z1;
}

// Rotate point around Z axis
void rotateZ(float& x, float& y, float angle) {
    float x1 = x * cos(angle) - y * sin(angle);
    float y1 = x * sin(angle) + y * cos(angle);
    x = x1;
    y = y1;
}

void drawCube() {
    float projected[8][2];  // 2D coordinates
    
    // Project each vertex
    for(int i = 0; i < 8; i++) {
        float x = vertices[i][0];
        float y = vertices[i][1];
        float z = vertices[i][2];
        
        // Apply rotations
        rotateX(y, z, angleX);
        rotateY(x, z, angleY);
        rotateZ(x, y, angleZ);
        
        // Project 3D to 2D
        float distance = 4;  // Distance from viewer to screen
        float z_factor = 1 / (distance - z);
        
        // Scale and translate to screen coordinates
        projected[i][0] = centerX + (x * z_factor * scale);
        projected[i][1] = centerY + (y * z_factor * scale);
    }
    
    // Clear screen
    tft.fillScreen(TFT_BLACK);
    
    // Draw edges
    for(int i = 0; i < 12; i++) {
        tft.drawLine(
            projected[edges[i][0]][0], projected[edges[i][0]][1],
            projected[edges[i][1]][0], projected[edges[i][1]][1],
            TFT_WHITE
        );
    }
}

void loop() {
    // Update rotation angles
    angleX += 0.03;
    angleY += 0.02;
    angleZ += 0.01;
    
    drawCube();
    delay(30);  // Control animation speed
}