Triangle physics seemingly done

data/map project.tiled-session

@@ -1,8 +1,8 @@
 {
-    "activeFile": "map.tmj",
+    "activeFile": "overworld.tsx",
     "expandedProjectPaths": [
-        "templates",
+        ".",
-        "."
+        "templates"
     ],
     "fileStates": {
         ":/automap-tiles.tsx": {
@@ -13,11 +13,11 @@
             "scaleInEditor": 1
         },
         "map.tmj": {
-            "scale": 4,
+            "scale": 3,
-            "selectedLayer": 2,
+            "selectedLayer": 0,
             "viewCenter": {
-                "x": 6599.375,
+                "x": 6520.166666666666,
-                "y": 6795.125
+                "y": 6836.833333333333
             }
         },
         "overworld.tsx": {
@@ -35,8 +35,8 @@
     "project": "map project.tiled-project",
     "property.type": "int",
     "recentFiles": [
-        "overworld.tsx",
         "map.tmj",
+        "overworld.tsx",
         "entities.tsx"
     ],
     "tileset.lastUsedFilter": "Tiled tileset files (*.tsx *.xml)",

src/dusk/entity/entity.c

@@ -101,9 +101,8 @@ void entityUpdate(entity_t *entity) {
         switch(TILE_META_DATA[tile].solidType) {
           case TILE_SOLID_FULL:
             collision = physicsCheckCircleAABB(
-              newX, newY, selfCircR,
+              fx248Addfx248(newX, halfTileWH), fx248Addfx248(newY, halfTileWH), selfCircR,
-              fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)),
+              lx, ty,
-              fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0)),
               FIXED248(TILE_WIDTH_HEIGHT, 0),
               FIXED248(TILE_WIDTH_HEIGHT, 0)
             );
@@ -111,44 +110,38 @@ void entityUpdate(entity_t *entity) {
 
           case TILE_SOLID_TRIANGLE_TOP_RIGHT:
             collision = physicsCheckCircleTriangle(
-              newX, newY, selfCircR,
+              fx248Addfx248(newX, halfTileWH), fx248Addfx248(newY, halfTileWH), selfCircR,
-              lx, ty,
+              rx, by,
               rx, ty,
-              rx, by
+              lx, ty
             );
             break;
 
-          // case TILE_SOLID_TRIANGLE_TOP_LEFT:
+          case TILE_SOLID_TRIANGLE_TOP_LEFT:
-          //   collision = physicsCheckCircleTriangle(
+            collision = physicsCheckCircleTriangle(
-          //     newX, newY, selfCircR,
+              fx248Addfx248(newX, halfTileWH), fx248Addfx248(newY, halfTileWH), selfCircR,
-          //     lx, ty,
+              lx, by,
-          //     rx, ty,
+              lx, ty,
-          //     lx, by
+              rx, ty
-          //   );
+            );
-          //   break;
+            break;
-          // case TILE_SOLID_TRIANGLE_BOTTOM_RIGHT:
-          //   collision = physicsCheckCircleTriangle(
-          //     newX, newY, selfCircR,
-          //     fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)),
-          //     fx248Addfx248(fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
-          //     fx248Addfx248(fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
-          //     fx248Addfx248(fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
-          //     fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)),
-          //     fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0))
-          //   );
-          //   break;
 
-          // case TILE_SOLID_TRIANGLE_BOTTOM_LEFT:
+          case TILE_SOLID_TRIANGLE_BOTTOM_RIGHT:
-          //   collision = physicsCheckCircleTriangle(
+            collision = physicsCheckCircleTriangle(
-          //     newX, newY, selfCircR,
+              fx248Addfx248(newX, halfTileWH), fx248Addfx248(newY, halfTileWH), selfCircR,
-          //     fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)),
+              rx, ty,
-          //     fx248Addfx248(fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
+              rx, by,
-          //     fx248Addfx248(fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
+              lx, by
-          //     fx248Addfx248(fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
+            );
-          //     fx248Addfx248(fx248Mulfx248(x, FIXED248(TILE_WIDTH_HEIGHT, 0)), FIXED248(TILE_WIDTH_HEIGHT, 0)),
+            break;
-          //     fx248Mulfx248(y, FIXED248(TILE_WIDTH_HEIGHT, 0))
+          case TILE_SOLID_TRIANGLE_BOTTOM_LEFT:
-          //   );
+            collision = physicsCheckCircleTriangle(
-          //   break;
+              fx248Addfx248(newX, halfTileWH), fx248Addfx248(newY, halfTileWH), selfCircR,
+              lx, ty,
+              lx, by,
+              rx, by
+            );
+            break;
 
           default:
             continue;

src/dusk/physics/physics.c

@@ -99,13 +99,155 @@ collisionresult_t physicsCheckCircleAABB(
   return result;
 }
 
+void physicsClosestPointOnSegment(
+  fixed248_t ax, fixed248_t ay,
+  fixed248_t bx, fixed248_t by,
+  fixed248_t px, fixed248_t py,
+  fixed248_t *outX, fixed248_t *outY
+) {
+  fixed248_t abx = fx248Subfx248(bx, ax);
+  fixed248_t aby = fx248Subfx248(by, ay);
+  fixed248_t apx = fx248Subfx248(px, ax);
+  fixed248_t apy = fx248Subfx248(py, ay);
+
+  fixed248_t abLenSq = fx248Addfx248(
+    fx248Mulfx248(abx, abx),
+    fx248Mulfx248(aby, aby)
+  );
+
+  if(abLenSq == FIXED248_ZERO) {
+    *outX = ax;
+    *outY = ay;
+    return;
+  }
+
+  fixed248_t t = fx248Divfx248(
+    fx248Addfx248(fx248Mulfx248(apx, abx), fx248Mulfx248(apy, aby)),
+    abLenSq
+  );
+
+  if(t < FIXED248_ZERO) t = FIXED248_ZERO;
+  if(t > FIXED248_ONE)  t = FIXED248_ONE;
+
+  *outX = fx248Addfx248(ax, fx248Mulfx248(abx, t));
+  *outY = fx248Addfx248(ay, fx248Mulfx248(aby, t));
+}
+
+bool_t physicsIsPointInTriangle(
+  fixed248_t px, fixed248_t py,
+  fixed248_t ax, fixed248_t ay,
+  fixed248_t bx, fixed248_t by,
+  fixed248_t cx, fixed248_t cy
+) {
+  fixed248_t abx = fx248Subfx248(bx, ax);
+  fixed248_t aby = fx248Subfx248(by, ay);
+  fixed248_t bcx = fx248Subfx248(cx, bx);
+  fixed248_t bcy = fx248Subfx248(cy, by);
+  fixed248_t cax = fx248Subfx248(ax, cx);
+  fixed248_t cay = fx248Subfx248(ay, cy);
+
+  fixed248_t apx = fx248Subfx248(px, ax);
+  fixed248_t apy = fx248Subfx248(py, ay);
+  fixed248_t bpx = fx248Subfx248(px, bx);
+  fixed248_t bpy = fx248Subfx248(py, by);
+  fixed248_t cpx = fx248Subfx248(px, cx);
+  fixed248_t cpy = fx248Subfx248(py, cy);
+
+  fixed248_t cross1 = fx248Subfx248(
+    fx248Mulfx248(abx, apy),
+    fx248Mulfx248(aby, apx)
+  );
+  fixed248_t cross2 = fx248Subfx248(
+    fx248Mulfx248(bcx, bpy),
+    fx248Mulfx248(bcy, bpx)
+  );
+  fixed248_t cross3 = fx248Subfx248(
+    fx248Mulfx248(cax, cpy),
+    fx248Mulfx248(cay, cpx)
+  );
+
+  bool_t hasNeg = (
+    (cross1 < FIXED248_ZERO) ||
+    (cross2 < FIXED248_ZERO) ||
+    (cross3 < FIXED248_ZERO)
+  );
+  
+  bool_t hasPos = (
+    (cross1 > FIXED248_ZERO) ||
+    (cross2 > FIXED248_ZERO) ||
+    (cross3 > FIXED248_ZERO)
+  );
+
+  return !(hasNeg && hasPos);
+}
+
 collisionresult_t physicsCheckCircleTriangle(
   fixed248_t circleX, fixed248_t circleY, fixed248_t circleR,
   fixed248_t triX0, fixed248_t triY0,
   fixed248_t triX1, fixed248_t triY1,
   fixed248_t triX2, fixed248_t triY2
 ) {
-  collisionresult_t result;
+  collisionresult_t result = { .hit = false };
-  result.hit = false;
+  fixed248_t vx[3] = { triX0, triX1, triX2 };
+  fixed248_t vy[3] = { triY0, triY1, triY2 };
+
+  fixed248_t closestX = FIXED248_ZERO;
+  fixed248_t closestY = FIXED248_ZERO;
+  fixed248_t normalX  = FIXED248_ZERO;
+  fixed248_t normalY  = FIXED248_ZERO;
+  fixed248_t minDistSq = FIXED248_MAX;
+
+  for(uint8_t i = 0; i < 3; ++i) {
+    uint8_t j = (i + 1) % 3;
+
+    fixed248_t testX, testY;
+    physicsClosestPointOnSegment(
+      vx[i], vy[i], vx[j], vy[j],
+      circleX, circleY, &testX, &testY
+    );
+
+    fixed248_t dx = fx248Subfx248(circleX, testX);
+    fixed248_t dy = fx248Subfx248(circleY, testY);
+    fixed248_t distSq = fx248Addfx248(
+      fx248Mulfx248(dx, dx),
+      fx248Mulfx248(dy, dy)
+    );
+
+    if(distSq < minDistSq) {
+      minDistSq = distSq;
+      closestX = testX;
+      closestY = testY;
+      normalX = dx;
+      normalY = dy;
+    }
+  }
+
+  fixed248_t dist = fx248Sqrt(minDistSq);
+  fixed248_t invDist = (
+    (dist != FIXED248_ZERO) ?
+    fx248Divfx248(FIXED248_ONE, dist) :
+    FIXED248_ONE
+  );
+
+  fixed248_t nx = fx248Mulfx248(-normalX, invDist);
+  fixed248_t ny = fx248Mulfx248(-normalY, invDist);
+
+  if(physicsIsPointInTriangle(
+    circleX, circleY, vx[0], vy[0], vx[1], vy[1], vx[2], vy[2]
+  )) {
+    result.hit = true;
+    result.depth = fx248Subfx248(circleR, dist);
+    result.normalX = nx;
+    result.normalY = ny;
+    return result;
+  }
+
+  if(dist < circleR) {
+    result.hit = true;
+    result.depth = fx248Subfx248(circleR, dist);
+    result.normalX = nx;
+    result.normalY = ny;
+  }
+
   return result;
-}
+}

src/dusk/physics/physics.h

@@ -48,6 +48,45 @@ collisionresult_t physicsCheckCircleAABB(
   fixed248_t aabbWidth, fixed248_t aabbHeight
 );
 
+/**
+ * Calculate the closest point on a line segment to a point.
+ * 
+ * @param ax X coordinate of the first endpoint of the segment.
+ * @param ay Y coordinate of the first endpoint of the segment.
+ * @param bx X coordinate of the second endpoint of the segment.
+ * @param by Y coordinate of the second endpoint of the segment.
+ * @param px X coordinate of the point.
+ * @param py Y coordinate of the point.
+ * @param outX Pointer to store the X coordinate of the closest point.
+ * @param outY Pointer to store the Y coordinate of the closest point.
+ */
+void physicsClosestPointOnSegment(
+  fixed248_t ax, fixed248_t ay,
+  fixed248_t bx, fixed248_t by,
+  fixed248_t px, fixed248_t py,
+  fixed248_t *outX, fixed248_t *outY
+);
+
+/**
+ * Check if a point is inside a triangle defined by three vertices.
+ * 
+ * @param px X coordinate of the point.
+ * @param py Y coordinate of the point.
+ * @param x0 X coordinate of the first vertex of the triangle.
+ * @param y0 Y coordinate of the first vertex of the triangle.
+ * @param x1 X coordinate of the second vertex of the triangle.
+ * @param y1 Y coordinate of the second vertex of the triangle.
+ * @param x2 X coordinate of the third vertex of the triangle.
+ * @param y2 Y coordinate of the third vertex of the triangle.
+ * @return true if the point is inside the triangle, false otherwise.
+ */
+bool_t physicsIsPointInTriangle(
+  fixed248_t px, fixed248_t py,
+  fixed248_t x0, fixed248_t y0,
+  fixed248_t x1, fixed248_t y1,
+  fixed248_t x2, fixed248_t y2
+);
+
 /**
  * Check for collision between a circle and a triangle.
  * 

src/dusk/util/fixed.h

@@ -19,6 +19,7 @@ typedef int32_t fixed248_t;
   (((f) * FIXED248_HIGH_MULTIPLIER) / 100) \
 ))
 #define FIXED248_ONE (FIXED248(1, 0))
+#define FIXED248_ZERO (FIXED248(0, 0))
 
 /**
  * Convert an int32_t value to a fixed248_t value.