Add esp source and header, with "utils" functions

src/features/esp.c

@@ -0,0 +1,66 @@
+
+#include "include/esp.h"
+#include "../include/globals.h"
+#include "../include/cvars.h"
+
+/* TODO: Move all these to utils.c */
+/* TODO: Replace src/features/include/X.h -> src/features/features.h */
+static bool is_alive(cl_entity_t* ent) {
+    return ent && ent->curstate.movetype != 6 && ent->curstate.movetype != 0;
+}
+
+static bool valid_client(cl_entity_t* ent) {
+    return is_alive(ent) && ent->index != localplayer->index;
+}
+
+static bool vec_is_zero(vec3_t v) {
+    return v[0] == 0.0f && v[1] == 0.0f && v[2] == 0.0f;
+}
+
+static char* get_name(int ent_idx) {
+    hud_player_info_t info;
+    i_engine->pfnGetPlayerInfo(ent_idx, &info);
+
+    return info.name;
+}
+
+typedef float vec2_t[2];
+static bool world_to_screen(vec3_t vec, vec2_t screen) {
+    int engine_w2s = i_engine->pTriAPI->WorldToScreen(vec, screen);
+    if (engine_w2s)
+        return false;
+
+    SCREENINFO scr_inf;
+    scr_inf.iSize = sizeof(SCREENINFO);
+    i_engine->pfnGetScreenInfo(&scr_inf);
+
+    /* If within bounds, transform to screen scale */
+    if (screen[0] < 1 && screen[1] < 1 && screen[0] > -1 && screen[1] > -1) {
+        screen[0] = screen[0] * (scr_inf.iWidth / 2) + (scr_inf.iWidth / 2);
+        screen[1] = -screen[1] * (scr_inf.iHeight / 2) + (scr_inf.iHeight / 2);
+
+        return true;
+    }
+
+    return false;
+}
+
+void esp(void) {
+    if (!CVAR_ON(esp))
+        return;
+
+    /* Iterate all clients */
+    for (int i = 1; i <= i_engine->GetMaxClients(); i++) {
+        cl_entity_t* ent = i_engine->GetEntityByIndex(i);
+
+        if (!valid_client(ent) || vec_is_zero(ent->origin))
+            continue;
+
+        float screen_point[2];
+        if (world_to_screen(ent->origin, screen_point)) {
+            i_engine->pfnDrawSetTextColor(1, 1, 1);
+            i_engine->pfnDrawConsoleString(screen_point[0], screen_point[1],
+                                           get_name(ent->index));
+        }
+    }
+}

src/features/include/esp.h

@@ -0,0 +1,6 @@
+#ifndef _ESP_H
+#define _ESP_H
+
+void esp(void);
+
+#endif /* _ESP_H */