Support for triangle

[marcelstoer]

Code provided by @mtsem as below.

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Hi,
I've written a part of code for this library a few years ago - modified and used locally on my computer, which enable to draw a triangle (outlined and filled). Since I am completely unfamiliar with Github and I don't wanna mess someones code, I would like to ask if someone would implement this part of code, if you are agree with it of course.

This part of code goes into OLEDDisplay.cpp file:

// Draw a triangle
void OLEDDisplay::drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2) {
  drawLine(x0, y0, x1, y1);
  drawLine(x1, y1, x2, y2);
  drawLine(x2, y2, x0, y0);
}

// Fill a triangle
void OLEDDisplay::fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2) {

  int16_t a, b, y, last;

  if (y0 > y1) {
    _swap_int16_t(y0, y1); _swap_int16_t(x0, x1);
  }
  if (y1 > y2) {
    _swap_int16_t(y2, y1); _swap_int16_t(x2, x1);
  }
  if (y0 > y1) {
    _swap_int16_t(y0, y1); _swap_int16_t(x0, x1);
  }

  if(y0 == y2) { 
    a = b = x0;
    if(x1 < a)      a = x1;
    else if(x1 > b) b = x1;
    if(x2 < a)      a = x2;
    else if(x2 > b) b = x2;
    drawHorizontalLine(a, y0, b-a+1);
    return;
  }

  int16_t
    dx01 = x1 - x0,
    dy01 = y1 - y0,
    dx02 = x2 - x0,
    dy02 = y2 - y0,
    dx12 = x2 - x1,
    dy12 = y2 - y1;
  int32_t
    sa   = 0,
    sb   = 0;

  if(y1 == y2) last = y1;   // Include y1 scanline
  else         last = y1-1; // Skip it

  for(y=y0; y<=last; y++) {
    a   = x0 + sa / dy01;
    b   = x0 + sb / dy02;
    sa += dx01;
    sb += dx02;

    if(a > b) _swap_int16_t(a,b);
    drawHorizontalLine(a, y, b-a+1);
  }

  sa = dx12 * (y - y1);
  sb = dx02 * (y - y0);
  for(; y<=y2; y++) {
    a   = x1 + sa / dy12;
    b   = x0 + sb / dy02;
    sa += dx12;
    sb += dx02;

    if(a > b) _swap_int16_t(a,b);
    drawHorizontalLine(a, y, b-a+1);
  }
}

This part of code goes into OLEDDisplay.h file:

void drawTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2);
void fillTriangle(int16_t x0, int16_t y0, int16_t x1, int16_t y1, int16_t x2, int16_t y2);

Best regards.

[marcelstoer]

Thanks a lot for your code. That screen is beautiful!

[mtsem]

Thank you. I apologize for any inconveniences according to putting a comment into inappropriate place. Best regards, Metod