texture atlas for atree connectors

js/atree.js

@@ -973,7 +973,8 @@ function render_AT(UI_elem, list_elem, tree) {
             const parent_id = parent_abil.id;
 
             let connect_elem = document.createElement("div");
-            connect_elem.style = "background-size: cover; width: 200%; height: 200%; position: absolute; top: -50%; left: -50%; image-rendering: pixelated;";
+            // connect_elem.style = "background-size: cover; width: 200%; height: 200%; position: absolute; top: -50%; left: -50%; image-rendering: pixelated;";
+            connect_elem.style = "width: 112.5%; height: 112.5%; position: absolute; top: -5.55%; left: -5.55%; image-rendering: pixelated; background-image: url('../media/atree/connectors.png'); background-size: 1200% 400%;"
             // connect up
             for (let i = ability.display.row - 1; i > parent_abil.display.row; i--) {
                 const coord = i + "," + ability.display.col;
@@ -1233,26 +1234,6 @@ function set_connector_type(connector_info) {  // left right up down
     }
 }
 
-// draw the connector onto the screen
-function atree_render_connection(atree_connectors_map) {
-    for (let i of atree_connectors_map.keys()) {
-        let connector_info = atree_connectors_map.get(i);
-        let connector_elem = connector_info.connector;
-        let connector_img = document.createElement('img');
-        set_connector_type(connector_info);
-        connector_img.src = '../media/atree/connect_'+connector_info.type+'.png';
-        connector_img.style = "width: 100%; height: 100%;"
-        connector_elem.replaceChildren(connector_img);
-        connector_info.highlight = [0, 0, 0, 0];
-        let target_elem = document.getElementById("atree-row-" + i.split(",")[0]).children[i.split(",")[1]];
-        if (target_elem.children.length != 0) {
-            // janky special case...
-            connector_elem.style.display = 'none';
-        }
-        target_elem.appendChild(connector_elem);
-    };
-};
-
 // toggle the state of a node.
 function atree_set_state(node_wrapper, new_state) {
     let icon = node_wrapper.ability.display.icon;
@@ -1280,6 +1261,48 @@ function atree_set_state(node_wrapper, new_state) {
     }
 };
 
+// first key is connector type, second key is highlight, then [x, y] pair of 0-index positions in the tile atlas
+const atreeConnectorAtlasPositions = {
+    "1100": {"0000": [0, 0], "1100": [1, 0]},
+    "1010": {"0000": [2, 0], "1010": [3, 0]},
+    "0110": {"0000": [4, 0], "0110": [5, 0]},
+    "1001": {"0000": [6, 0], "1001": [7, 0]},
+    "0101": {"0000": [8, 0], "0101": [9, 0]},
+    "0011": {"0000": [10, 0], "0011": [11, 0]},
+    "1101": {"0000": [0, 1], "1101": [1, 1], "1100": [2, 1], "1001": [3, 1], "0101": [4, 1]},
+    "0111": {"0000": [5, 1], "0111": [6, 1], "0110": [7, 1], "0101": [8, 1], "0011": [9, 1]},
+    "1110": {"0000": [0, 2], "1110": [1, 2], "1100": [2, 2], "1010": [3, 2], "0110": [4, 2]},
+    "1011": {"0000": [5, 2], "1011": [6, 2], "1010": [7, 2], "1001": [8, 2], "0011": [9, 2]},
+    "1111": {"0000": [0, 3], "1111": [1, 3], "1110": [2, 3], "1101": [3, 3], "1100": [4, 3], "1011": [5, 3], "1010": [6, 3], "1001": [7, 3], "0111": [8, 3], "0110": [9, 3], "0101": [10, 3], "0011": [11, 3]}
+}
+function atlasBGPositionCalc(pos, atlasSize) {
+    // https://css-tricks.com/focusing-background-image-precise-location-percentages/
+    // p = (c + 0.5/z - 0.5) * z/(z - 1) + 0.5
+    // z = num tiles in direction
+    // c = starting pos of tile in percent of total atlas (equal to index/z)
+    let x = ((pos[0]/atlasSize[0]) + 0.5/atlasSize[0] - 0.5) * atlasSize[0]/(atlasSize[0] - 1) + 0.5
+    let y = ((pos[1]/atlasSize[1]) + 0.5/atlasSize[1] - 0.5) * atlasSize[1]/(atlasSize[1] - 1) + 0.5
+    return (x * 100) + "% " + (y * 100) + "%" // multiply by 100 to convert decimal to percent
+}
+
+// draw the connector onto the screen
+function atree_render_connection(atree_connectors_map) {
+    for (let i of atree_connectors_map.keys()) {
+        let connector_info = atree_connectors_map.get(i);
+        let connector_elem = connector_info.connector;
+        set_connector_type(connector_info);
+        connector_info.highlight = [0, 0, 0, 0];
+        connector_elem.style.backgroundPosition = atlasBGPositionCalc(atreeConnectorAtlasPositions[connector_info.type]["0000"], [12, 4]);
+        let target_elem = document.getElementById("atree-row-" + i.split(",")[0]).children[i.split(",")[1]];
+        if (target_elem.children.length != 0) {
+            // janky special case...
+            connector_elem.style.display = 'none';
+        }
+        target_elem.appendChild(connector_elem);
+    };
+};
+
+// update the connector (after being drawn the first time by atree_render_connection)
 function atree_set_edge(atree_connectors_map, parent, child, state) {
     const connectors = child.connectors.get(parent);
     const parent_row = parent.ability.display.row;
@@ -1294,8 +1317,6 @@ function atree_set_edge(atree_connectors_map, parent, child, state) {
         let connector_info = atree_connectors_map.get(connector_label);
         let connector_elem = connector_info.connector;
         let highlight_state = connector_info.highlight; // left right up down
-        let connector_img_elem = document.createElement("img");
-        connector_img_elem.style = "width: 100%; height: 100%;";
         const ctype = connector_info.type;
         let num_1s = 0;
         for (let i = 0; i < 4; i++) {
@@ -1323,23 +1344,16 @@ function atree_set_edge(atree_connectors_map, parent, child, state) {
             for (let i = 0; i < 4; i++) {
                 render += highlight_state[i] === 0 ? "0" : "1";
             }
-            if (render == "0000") {
+            connector_elem.style.backgroundPosition = atlasBGPositionCalc(atreeConnectorAtlasPositions[ctype][render], [12, 4]);
-                connector_img_elem.src = "../media/atree/connect_" + ctype + ".png";
-            } else {
-                connector_img_elem.src = "../media/atree/connect_" + ctype + "_" + render + ".png";
-            }
-            connector_elem.replaceChildren(connector_img_elem);
             continue;
-        }
+        } else {
             // lol bad overloading, [0] is just the whole state
             highlight_state[0] += state_delta;
             if (highlight_state[0] > 0) {
-            connector_img_elem.src = '../media/atree/connect_' + ctype + '_1.png';
+                connector_elem.style.backgroundPosition = atlasBGPositionCalc(atreeConnectorAtlasPositions[ctype][ctype], [12, 4]);
-            connector_elem.replaceChildren(connector_img_elem);
+            } else {
+                connector_elem.style.backgroundPosition = atlasBGPositionCalc(atreeConnectorAtlasPositions[ctype]["0000"], [12, 4]);
             }
-        else {
-            connector_img_elem.src = '../media/atree/connect_'+ctype+'.png';
-            connector_elem.replaceChildren(connector_img_elem);
         }
     }
 }