From 1cce542cd566d859ecec3386bf8e19be1626f1d7 Mon Sep 17 00:00:00 2001
From: Gabor <kisvegabor@gmail.com>
Date: Fri, 17 Feb 2017 11:29:17 +0100
Subject: [PATCH] lv_draw: triangle draw added for experimental usage

---
 lv_draw/lv_draw.c | 136 ++++++++++++++++++++++++++++++++++++++++++++++
 lv_draw/lv_draw.h |  13 +++++
 2 files changed, 149 insertions(+)

diff --git a/lv_draw/lv_draw.c b/lv_draw/lv_draw.c
index 8734b4638..c82d131df 100644
--- a/lv_draw/lv_draw.c
+++ b/lv_draw/lv_draw.c
@@ -48,6 +48,11 @@ static void lv_draw_rect_border_corner(const area_t * cords_p, const area_t * ma
 static uint16_t lv_draw_rect_radius_corr(uint16_t r, cord_t w, cord_t h);
 #endif /*USE_LV_RECT != 0*/
 
+
+#if USE_LV_TRIANGLE != 0
+static void point_swap(point_t * p1, point_t * p2);
+#endif
+
 /**********************
  *  STATIC VARIABLES
  **********************/
@@ -115,6 +120,115 @@ void lv_draw_rect(const area_t * cords_p, const area_t * mask_p,
 }
 #endif /*USE_LV_RECT != 0*/
 
+#if USE_LV_TRIANGLE != 0
+/**
+ *
+ * @param points pointer to an array with 3 points
+ * @param mask_p the triangle will be drawn only in this mask
+ * @param color color of the triangle
+ */
+void lv_draw_triangle(const point_t * points, const area_t * mask_p, color_t color)
+{
+    point_t tri[3];
+
+    memcpy(tri, points, sizeof(tri));
+
+    /*Sort the vertices according to their y coordinate (0: y max, 1: y mid, 2:y min)*/
+    if(tri[1].y < tri[0].y) point_swap(&tri[1], &tri[0]);
+    if(tri[2].y < tri[1].y) point_swap(&tri[2], &tri[1]);
+    if(tri[1].y < tri[0].y) point_swap(&tri[1], &tri[0]);
+
+    /*Return is the triangle is degenerated*/
+    if(tri[0].x == tri[1].x && tri[0].y == tri[1].y) return;
+    if(tri[1].x == tri[2].x && tri[1].y == tri[2].y) return;
+    if(tri[0].x == tri[2].x && tri[0].y == tri[2].y) return;
+
+    if(tri[0].x == tri[1].x && tri[1].x == tri[2].x) return;
+    if(tri[0].y == tri[1].y && tri[1].y == tri[2].y) return;
+
+    /*Draw the triangle*/
+    point_t edge1;
+    cord_t dx1 = MATH_ABS(tri[0].x - tri[1].x);
+    cord_t sx1 = tri[0].x < tri[1].x ? 1 : -1;
+    cord_t dy1 = MATH_ABS(tri[0].y - tri[1].y);
+    cord_t sy1 = tri[0].y < tri[1].y ? 1 : -1;
+    cord_t err1 = (dx1 > dy1 ? dx1 : -dy1) / 2;
+    cord_t err_tmp1;
+
+    point_t edge2;
+    cord_t dx2 = MATH_ABS(tri[0].x - tri[2].x);
+    cord_t sx2 = tri[0].x < tri[2].x ? 1 : -1;
+    cord_t dy2 = MATH_ABS(tri[0].y - tri[2].y);
+    cord_t sy2 = tri[0].y < tri[2].y ? 1 : -1;
+    cord_t err2 = (dx1 > dy2 ? dx2 : -dy2) / 2;
+    cord_t err_tmp2;
+
+    cord_t y1_tmp;
+    cord_t y2_tmp;
+
+    edge1.x = tri[0].x;
+    edge1.y = tri[0].y;
+    edge2.x = tri[0].x;
+    edge2.y = tri[0].y;
+    area_t act_area;
+    area_t draw_area;
+
+    while(1) {
+        act_area.x1 = edge1.x;
+        act_area.x2 = edge2.x ;
+        act_area.y1 = edge1.y;
+        act_area.y2 = edge2.y ;
+
+
+        draw_area.x1 = MATH_MIN(act_area.x1, act_area.x2);
+        draw_area.x2 = MATH_MAX(act_area.x1, act_area.x2);
+        draw_area.y1 = MATH_MIN(act_area.y1, act_area.y2);
+        draw_area.y2 = MATH_MAX(act_area.y1, act_area.y2);
+        draw_area.x2--; /*Do not draw most right pixel because it will be drawn by the adjacent triangle*/
+        fill_fp(&draw_area, mask_p, color, OPA_50);
+
+        /*Calc. the next point of edge1*/
+        y1_tmp = edge1.y;
+        do {
+            if (edge1.x == tri[1].x && edge1.y == tri[1].y) {
+
+                dx1 = MATH_ABS(tri[1].x - tri[2].x);
+                sx1 = tri[1].x < tri[2].x ? 1 : -1;
+                dy1 = MATH_ABS(tri[1].y - tri[2].y);
+                sy1 = tri[1].y < tri[2].y ? 1 : -1;
+                err1 = (dx1 > dy1 ? dx1 : -dy1) / 2;
+            }
+            else if (edge1.x == tri[2].x && edge1.y == tri[2].y) return;
+            err_tmp1 = err1;
+            if (err_tmp1 >-dx1) {
+                err1 -= dy1;
+                edge1.x += sx1;
+            }
+            if (err_tmp1 < dy1) {
+                err1 += dx1;
+                edge1.y += sy1;
+            }
+        } while(edge1.y == y1_tmp);
+
+        /*Calc. the next point of edge2*/
+        y2_tmp = edge2.y;
+        do {
+            if (edge2.x == tri[2].x && edge2.y == tri[2].y) return;
+            err_tmp2 = err2;
+            if (err_tmp2 > -dx2) {
+                err2 -= dy2;
+                edge2.x += sx2;
+            }
+            if (err_tmp2 < dy2) {
+                err2 += dx2;
+                edge2.y += sy2;
+            }
+        } while(edge2.y == y2_tmp);
+    }
+}
+
+#endif
+
 #if USE_LV_LABEL != 0
 /**
  * Write a text
@@ -935,3 +1049,25 @@ static uint16_t lv_draw_rect_radius_corr(uint16_t r, cord_t w, cord_t h)
 
 #endif /*USE_LV_RECT != 0*/
 
+
+#if USE_LV_TRIANGLE != 0
+/**
+ * Swap two points
+ * p1 pointer to the first point
+ * p2 pointer to the second point
+ */
+static void point_swap(point_t * p1, point_t * p2)
+{
+    point_t tmp;
+    tmp.x = p1->x;
+    tmp.y = p1->y;
+
+    p1->x = p2->x;
+    p1->y = p2->y;
+
+    p2->x = tmp.x;
+    p2->y = tmp.y;
+
+}
+
+#endif
diff --git a/lv_draw/lv_draw.h b/lv_draw/lv_draw.h
index 088099755..728e9213a 100644
--- a/lv_draw/lv_draw.h
+++ b/lv_draw/lv_draw.h
@@ -42,6 +42,19 @@ void lv_draw_rect(const area_t * cords_p, const area_t * mask_p,
                     const lv_rects_t * rects_p, opa_t opa);
 #endif
 
+
+/*Experimental use for 3D modeling*/
+#define USE_LV_TRIANGLE 0
+#if USE_LV_TRIANGLE != 0
+/**
+ *
+ * @param points pointer to an array with 3 points
+ * @param mask_p the triangle will be drawn only in this mask
+ * @param color color of the triangle
+ */
+void lv_draw_triangle(const point_t * points, const area_t * mask_p, color_t color);
+#endif
+
 /**
  * Write a text
  * @param cords_p coordinates of the label