From b802e8edef68937e3ab00fb9b2e74b03ff5195bc Mon Sep 17 00:00:00 2001
From: Sylvain PILLOT <pillot.sylvain@gmail.com>
Date: Thu, 29 Feb 2024 21:34:42 +0100
Subject: [PATCH] added dpoly() rendering method

---
 src/render/dpoly.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 src/render/dpoly.c

diff --git a/src/render/dpoly.c b/src/render/dpoly.c
new file mode 100644
index 0000000..5d317be
--- /dev/null
+++ b/src/render/dpoly.c
@@ -0,0 +1,67 @@
+#include <gint/defs/util.h>
+#include <gint/display.h>
+
+void dpoly(int *polyX, int *polyY, int polyCorners, int fill_color, int border_color){
+
+  if (polyCorners<=2) return;
+
+  if (fill_color == C_NONE && border_color == C_NONE)
+    return;
+
+  if (fill_color != C_NONE) {
+    
+    float *nodeX, pixelX, pixelY, swap ;
+    int i, j, nodes;
+    
+    nodeX = malloc( polyCorners * sizeof(float));
+
+    //  Loop through the rows of the image.
+    for (pixelY=0; pixelY<DHEIGHT; pixelY++) {
+      
+      //  Build a list of nodes.
+      nodes=0; j=polyCorners-1;
+      for (i=0; i<polyCorners; i++) {
+        if ((polyY[i]<(float) pixelY && polyY[j]>=(float) pixelY)
+        ||  (polyY[j]<(float) pixelY && polyY[i]>=(float) pixelY)) {
+          nodeX[nodes++]=(int) (polyX[i]+(pixelY-polyY[i])/(polyY[j]-polyY[i])*(polyX[j]-polyX[i]));
+        }
+        j=i;
+      }
+
+      //  Sort the nodes, via a simple “Bubble” sort.
+      i=0;
+      while (i<nodes-1) {
+        if (nodeX[i]>nodeX[i+1]) {
+          swap=nodeX[i]; nodeX[i]=nodeX[i+1]; nodeX[i+1]=swap; if (i) i--;
+        }
+        else {
+          i++;
+        }
+      }
+
+      //  Fill the pixels between node pairs.
+      for (i=0; i<nodes; i+=2) {
+        if (nodeX[i  ]>=DWIDTH) break;
+        if (nodeX[i+1]<= 0 ) break;
+        if (nodeX[i  ]< 0 ) nodeX[i  ]=0 ;
+        if (nodeX[i+1]> DWIDTH) nodeX[i+1]=DWIDTH;
+        //for (pixelX=nodeX[i]; pixelX<nodeX[i+1]; pixelX++) fillPixel(pixelX,pixelY);
+        dline(nodeX[i], pixelY, nodeX[i+1], pixelY, fill_color);
+      }
+    }       
+
+    free(nodeX);
+  }
+
+  if (border_color != C_NONE) {
+    for (int i = 0; i < polyCorners; i++) {
+      int px = polyX[i];
+      int py = polyY[i];
+      int px2 = polyX[(i + 1) % polyCorners];
+      int py2 = polyY[(i + 1) % polyCorners];
+      dline(px, py, px2, py2, border_color);
+    }
+  }
+
+  return;
+}