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triangles!

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1 parent cacf67a commit eb78fc66930abc70383a511c2ac8c5585f60a447 @ladyada ladyada committed Mar 15, 2012
Showing with 87 additions and 1 deletion.
  1. +87 −1 Adafruit_GFX.cpp
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88 Adafruit_GFX.cpp
@@ -226,7 +226,7 @@ uint16_t h, uint16_t r, uint16_t color) {
// fill a rounded rectangle!
void Adafruit_GFX::fillRoundRect(uint16_t x, uint16_t y, uint16_t w,
-uint16_t h, uint16_t r, uint16_t color) {
+ uint16_t h, uint16_t r, uint16_t color) {
// smarter version
fillRect(x+r, y, w-2*r, h, color);
@@ -235,6 +235,92 @@ uint16_t h, uint16_t r, uint16_t color) {
fillCircleHelper(x+r , y+r, r, 2, h-2*r-1, color);
}
+// draw a triangle!
+void Adafruit_GFX::drawTriangle(uint16_t x0, uint16_t y0,
+ uint16_t x1, uint16_t y1,
+ uint16_t x2, uint16_t y2, uint16_t color) {
+ drawLine(x0, y0, x1, y1, color);
+ drawLine(x1, y1, x2, y2, color);
+ drawLine(x2, y2, x0, y0, color);
+}
+
+// fill a triangle!
+void Adafruit_GFX::fillTriangle ( uint16_t x0, uint16_t y0,
+ uint16_t x1, uint16_t y1,
+ uint16_t x2, uint16_t y2, uint16_t color) {
+
+ int16_t a, b, y, last;
+
+ // Sort coordinates by Y order (y2 >= y1 >= y0)
+ if (y0 > y1) {
+ swap(y0, y1); swap(x0, x1);
+ }
+ if (y1 > y2) {
+ swap(y2, y1); swap(x2, x1);
+ }
+ if (y0 > y1) {
+ swap(y0, y1); swap(x0, x1);
+ }
+
+ if(y0 == y2) { // Handle awkward all-on-same-line case as its own thing
+ 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;
+ drawFastHLine(a, y0, b-a+1, color);
+ return;
+ }
+
+ int16_t
+ dx01 = x1 - x0,
+ dy01 = y1 - y0,
+ dx02 = x2 - x0,
+ dy02 = y2 - y0,
+ dx12 = x2 - x1,
+ dy12 = y2 - y1,
+ sa = 0,
+ sb = 0;
+
+ // For upper part of triangle, find scanline crossings for segments
+ // 0-1 and 0-2. If y1=y2 (flat-bottomed triangle), the scanline y1
+ // is included here (and second loop will be skipped, avoiding a /0
+ // error there), otherwise scanline y1 is skipped here and handled
+ // in the second loop...which also avoids a /0 error here if y0=y1
+ // (flat-topped triangle).
+ 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;
+ /* longhand:
+ a = x0 + (x1 - x0) * (y - y0) / (y1 - y0);
+ b = x0 + (x2 - x0) * (y - y0) / (y2 - y0);
+ */
+ if(a > b) swap(a,b);
+ drawFastHLine(a, y, b-a+1, color);
+ }
+
+ // For lower part of triangle, find scanline crossings for segments
+ // 0-2 and 1-2. This loop is skipped if y1=y2.
+ sa = dx12 * (y - y1);
+ sb = dx02 * (y - y0);
+ for(; y<=y2; y++) {
+ a = x1 + sa / dy12;
+ b = x0 + sb / dy02;
+ sa += dx12;
+ sb += dx02;
+ /* longhand:
+ a = x1 + (x2 - x1) * (y - y1) / (y2 - y1);
+ b = x0 + (x2 - x0) * (y - y0) / (y2 - y0);
+ */
+ if(a > b) swap(a,b);
+ drawFastHLine(a, y, b-a+1, color);
+ }
+}
void Adafruit_GFX::drawBitmap(uint16_t x, uint16_t y,
const uint8_t *bitmap, uint16_t w, uint16_t h,

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