From 91d86a4f85732a6f689ec500d083751d3c634b80 Mon Sep 17 00:00:00 2001
From: Zack Buhman <zack@buhman.org>
Date: Mon, 9 Mar 2026 23:24:34 -0500
Subject: [PATCH] use line points from eye position

---
 include/test.h       |  3 ++-
 main.lua             |  8 +++++--
 shader/lighting.frag |  5 ++++-
 src/test.cpp         | 50 +++++++++++++++++++++++++++++++++-----------
 4 files changed, 50 insertions(+), 16 deletions(-)

diff --git a/include/test.h b/include/test.h
index da9779a..380d938 100644
--- a/include/test.h
+++ b/include/test.h
@@ -9,7 +9,8 @@ extern "C" {
   void kb_update(int up, int down, int left, int right);
   void update(float lx, float ly, float rx, float ry, float tl, float tr,
               int up, int down, int left, int right,
-              int a, int b, int x, int y);
+              int a, int b, int x, int y,
+              int leftshoulder, int rightshoulder);
 
 #ifdef __cplusplus
 }
diff --git a/main.lua b/main.lua
index b9b1425..f2c1986 100644
--- a/main.lua
+++ b/main.lua
@@ -11,7 +11,8 @@ void draw();
 void kb_update(int kbup, int kbdown, int kbleft, int kbright);
 void update(float lx, float ly, float rx, float ry, float tl, float tr,
             int up, int down, int left, int right,
-            int a, int b, int x, int y);
+            int a, int b, int x, int y,
+            int leftshoulder, int rightshoulder);
 ]]
    local source_path = love.filesystem.getSource()
    test = ffi.load(source_path .. "/test.so")
@@ -35,10 +36,13 @@ local update = function(dt)
       local b = joystick:isGamepadDown("b")
       local x = joystick:isGamepadDown("x")
       local y = joystick:isGamepadDown("y")
+      local leftshoulder = joystick:isGamepadDown("leftshoulder")
+      local rightshoulder = joystick:isGamepadDown("rightshoulder")
 
       test.update(lx, ly, rx, ry, tl, tr,
                   up, down, left, right,
-                  a, b, x, y)
+                  a, b, x, y,
+                  leftshoulder, rightshoulder)
    end
 
    local up = love.keyboard.isDown("up")
diff --git a/shader/lighting.frag b/shader/lighting.frag
index 291f122..ed27865 100644
--- a/shader/lighting.frag
+++ b/shader/lighting.frag
@@ -32,9 +32,12 @@ void main()
     //float attenuation = 1.0 / (1.0 + Linear * light_distance + Quadratic * light_distance * light_distance);
 
     float attenuation = 1.0 / (1.0 + Quadratic * light_distance * light_distance);
-    out_color += color.xyz * attenuation * diffuse;
+    //out_color += color.xyz * attenuation * diffuse;
     //out_color = vec3(diffuse);
   }
+  vec3 light_direction = normalize(Eye.xyz - position.xyz);
+  float diffuse = max(dot(normal.xyz, light_direction), 0.0);
+  out_color = color.xyz * diffuse;
 
   Color = vec4(out_color, 1.0);
 }
diff --git a/src/test.cpp b/src/test.cpp
index b7bdddd..77b2a90 100644
--- a/src/test.cpp
+++ b/src/test.cpp
@@ -470,7 +470,7 @@ static_assert((sizeof (short_point)) == 6);
 short_point line_points[128];
 static int line_point_ix = 0;
 
-void line_point(int x, int y, int z)
+void append_line_point(int x, int y, int z)
 {
   if (line_point_ix >= 128)
     return;
@@ -543,22 +543,38 @@ void load_line_instance_buffer()
   glBindBuffer(GL_ARRAY_BUFFER, 0);
 }
 
+struct line_state {
+  struct {
+    int x;
+    int y;
+    int z;
+  } point[2];
+};
+static line_state line_state = {};
+
 void load_line()
 {
-  int x1 = -55;
-  int z1 = 48;
-  int y1 = 50;
-
-  int x2 = -60;
-  int z2 = 55;
-  int y2 = 53;
-
   line_point_ix = 0;
-  bresenham(x1, y1, z1, x2, y2, z2, line_point);
+  bresenham(line_state.point[0].x, line_state.point[0].y, line_state.point[0].z,
+            line_state.point[1].x, line_state.point[1].y, line_state.point[1].z,
+            append_line_point);
 
   load_line_instance_buffer();
 }
 
+void load_line_point_from_eye(int point_ix)
+{
+  int x = XMVectorGetX(view_state.eye);
+  int y = XMVectorGetY(view_state.eye);
+  int z = XMVectorGetZ(view_state.eye);
+
+  line_state.point[point_ix].x = x;
+  line_state.point[point_ix].y = z;
+  line_state.point[point_ix].z = y;
+
+  load_line();
+}
+
 void load(const char * source_path)
 {
   g_source_path_length = strlen(source_path);
@@ -612,7 +628,6 @@ void load(const char * source_path)
   load_line_vertex_attributes();
 
   glGenBuffers(1, &line_instance_buffer);
-  load_line();
 }
 
 float _ry = 0.0;
@@ -635,7 +650,8 @@ void kb_update(int up, int down, int left, int right)
 
 void update(float lx, float ly, float rx, float ry, float tl, float tr,
             int up, int down, int left, int right,
-            int a, int b, int x, int y)
+            int a, int b, int x, int y,
+            int leftshoulder, int rightshoulder)
 {
   //view_state.yaw += rx;
   XMMATRIX mrz = XMMatrixRotationZ(rx * -0.035);
@@ -662,6 +678,13 @@ void update(float lx, float ly, float rx, float ry, float tl, float tr,
   lighting.linear += 0.01 * x + -0.01 * y;
   if (lighting.linear < 0.0f)
     lighting.linear = 0.0f;
+
+  if (leftshoulder) {
+    load_line_point_from_eye(0);
+  }
+  if (rightshoulder) {
+    load_line_point_from_eye(1);
+  }
 }
 
 static inline int popcount(int x)
@@ -860,6 +883,9 @@ void draw_lighting()
 
 void draw_line()
 {
+  if (line_point_ix == 0)
+    return;
+
   glUseProgram(line_program);
 
   glBlendFunc(GL_ONE, GL_ZERO);