From e6d4fbd1824f9a58ba4d19af23193bca98c5b5be Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Sun, 8 Mar 2026 14:02:35 -0500
Subject: [PATCH] flying first-person camera

---
 include/test.h |  3 ++-
 main.lua       | 12 ++++++++++--
 src/test.cpp   | 43 ++++++++++++++++++++++++++++++-------------
 3 files changed, 42 insertions(+), 16 deletions(-)

diff --git a/include/test.h b/include/test.h
index 96e34a7..aa4a777 100644
--- a/include/test.h
+++ b/include/test.h
@@ -6,7 +6,8 @@ extern "C" {
 
   void load();
   void draw();
-  void update(float lx, float ly, float ry);
+  void update(float lx, float ly, float rx, float ry, float tl, float tr,
+              int up, int down, int left, int right);
 
 #ifdef __cplusplus
 }
diff --git a/main.lua b/main.lua
index 8161182..9bf1941 100644
--- a/main.lua
+++ b/main.lua
@@ -7,7 +7,8 @@ function init()
    ffi.cdef[[
 void load();
 void draw();
-void update(float lx, float ly, float ry);
+void update(float lx, float ly, float rx, float ry, float tl, float tr,
+            int up, int down, int left, int right);
 ]]
    test = ffi.load("./test.so")
    test.load()
@@ -18,8 +19,15 @@ local update = function(dt)
    for _, joystick in ipairs(joysticks) do
       local lx = joystick:getGamepadAxis("leftx")
       local ly = joystick:getGamepadAxis("lefty")
+      local rx = joystick:getGamepadAxis("rightx")
       local ry = joystick:getGamepadAxis("righty")
-      test.update(lx, ly, ry)
+      local tl = joystick:getGamepadAxis("triggerleft")
+      local tr = joystick:getGamepadAxis("triggerright")
+      local up = joystick:isGamepadDown("dpup")
+      local down = joystick:isGamepadDown("dpdown")
+      local left = joystick:isGamepadDown("dpleft")
+      local right = joystick:isGamepadDown("dpright")
+      test.update(lx, ly, rx, ry, tl, tr, up, down, left, right)
    end
 end
 
diff --git a/src/test.cpp b/src/test.cpp
index c3d900c..752468e 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -237,6 +237,15 @@ extern "C" {
   void * SDL_GL_GetProcAddress(const char *proc);
 }
 
+struct view_state {
+  XMVECTOR up;
+  XMVECTOR eye;
+  XMVECTOR direction;
+  float fov;
+};
+
+view_state view_state;
+
 void load()
 {
   fprintf(stderr, "getproc %p\n", SDL_GL_GetProcAddress);
@@ -245,6 +254,13 @@ void load()
   load_program();
   load_buffers();
   load_textures();
+
+  view_state.up = XMVectorSet(0.0f, 0.0f, 1.0f, 0.0f);
+  view_state.eye = XMVectorSet(0, 0, 0, 1);
+  view_state.direction = XMVectorSet(1, 0, 0, 0);
+
+  view_state.fov = 1.0;
+
   //load_texture_shader_storage();
 
   //unsigned int textures_layout = glGetUniformBlockIndex(test_program, "TexturesLayout");
@@ -252,15 +268,18 @@ void load()
   //printf("textures_layout %d\n", textures_layout);
 }
 
-static float vx = 0.0;
-static float vy = 0.0;
-static float vz = 0.0;
-
-void update(float lx, float ly, float ry)
+void update(float lx, float ly, float rx, float ry, float tl, float tr,
+            int up, int down, int left, int right)
 {
-  vx += 2.5 * lx;
-  vy += -2.5 * ry;
-  vz += -2.5 * ly;
+  //view_state.yaw += rx;
+  XMMATRIX mrz = XMMatrixRotationZ(rx * -0.035);
+  XMMATRIX mry = XMMatrixRotationY(ry * -0.035);
+  view_state.direction = XMVector3Transform(view_state.direction, mrz * mry);
+
+  XMVECTOR normal = XMVector3Cross(view_state.direction, view_state.up);
+  view_state.eye += view_state.direction * -ly + normal * lx + view_state.up * (tl - tr);
+
+  view_state.fov += 0.01 * up + -0.01 * down;
 }
 
 static inline int popcount(int x)
@@ -270,12 +289,10 @@ static inline int popcount(int x)
 
 void draw()
 {
-  XMVECTOR eye = XMVectorSet(vx + -50.0f, vz + -50.0f, vy + 150.0f, 0.0f);
-  XMVECTOR at = XMVectorSet(vx + 50.0f, vz + 50.0f, vy + 50.0f, 0.0f);
-  XMVECTOR up = XMVectorSet(0.0f, 0.0f, 1.0f, 0.0f);
-  XMMATRIX view = XMMatrixLookAtRH(eye, at, up);
+  XMVECTOR at = XMVectorAdd(view_state.eye, view_state.direction);
+  XMMATRIX view = XMMatrixLookAtRH(view_state.eye, at, view_state.up);
 
-  float fov_angle_y = XMConvertToRadians(45 * 0.75);
+  float fov_angle_y = XMConvertToRadians(45 * view_state.fov);
   float aspect_ratio = 1.0;
   float near_z = 1.0;
   float far_z = 0.1;