From fc6ebb73b8556b9b5456b18044ed0e3141775d48 Mon Sep 17 00:00:00 2001
From: duck <duck@duckdesktop>
Date: Sat, 20 Sep 2025 19:03:36 +0500
Subject: [PATCH] Use reversed infinite projection for camera

---
 data/shaders/basic.vert  |  2 +-
 src/graphics.zig         |  5 ++---
 src/graphics/camera.zig  | 18 +++++++-----------
 src/graphics/presets.zig |  2 +-
 src/world.zig            |  2 +-
 5 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/data/shaders/basic.vert b/data/shaders/basic.vert
index 3797185..f5e3dec 100644
--- a/data/shaders/basic.vert
+++ b/data/shaders/basic.vert
@@ -13,6 +13,6 @@ layout(set = 1, binding = 1) uniform Object{
 
 void main() {
     gl_Position = vec4(inCoord, 1.0) * object.transform * camera.transform;
-    gl_ClipDistance[0] = gl_Position.z;
+    gl_ClipDistance[0] = gl_Position.w - gl_Position.z;
     outUV = inUV;
 }
diff --git a/src/graphics.zig b/src/graphics.zig
index 56b39be..a43f353 100644
--- a/src/graphics.zig
+++ b/src/graphics.zig
@@ -142,7 +142,6 @@ pub fn create() void {
     Graphics.camera = Camera{
         .transform = .{},
         .near = 1.0 / 16.0,
-        .far = 128.0,
         .lens = 1.5,
         .aspect = 16.0 / 9.0,
         .matrix = undefined,
@@ -193,7 +192,7 @@ pub fn beginDraw() bool {
         .mip_level = 0,
         .texture = Graphics.fsaa_target,
     }, 1, &.{
-        .clear_depth = 1.0,
+        .clear_depth = 0.0,
         .load_op = sdl.GPU_LOADOP_CLEAR,
         .store_op = sdl.GPU_STOREOP_DONT_CARE,
         .stencil_load_op = sdl.GPU_STOREOP_DONT_CARE,
@@ -219,7 +218,7 @@ pub fn clearDepth() void {
         .mip_level = 0,
         .texture = Graphics.fsaa_target,
     }, 1, &.{
-        .clear_depth = 1.0,
+        .clear_depth = 0.0,
         .load_op = sdl.GPU_LOADOP_CLEAR,
         .store_op = sdl.GPU_STOREOP_DONT_CARE,
         .stencil_load_op = sdl.GPU_STOREOP_DONT_CARE,
diff --git a/src/graphics/camera.zig b/src/graphics/camera.zig
index 8790923..ebbd7e2 100644
--- a/src/graphics/camera.zig
+++ b/src/graphics/camera.zig
@@ -8,7 +8,6 @@ transform: Transform,
 /// tangent of the half of the view angle (90 degress = 1 "lens")
 lens: f32,
 near: f32,
-far: f32,
 /// width = height * aspect
 aspect: f32,
 
@@ -19,14 +18,11 @@ pub fn computeMatrix(camera: *Camera) void {
 
     const xx = 1.0 / (camera.lens * camera.aspect);
     const yy = 1.0 / camera.lens;
-    const fnmod = 1.0 / (camera.far - camera.near);
-    const zz = camera.far * fnmod;
-    const wz = -camera.near * camera.far * fnmod;
     const projection = @Vector(16, f32){
-        xx, 0,  0,   0,
-        0,  yy, 0,   0,
-        0,  0,  -zz, wz,
-        0,  0,  -1,  0,
+        xx, 0,  0,  0,
+        0,  yy, 0,  0,
+        0,  0,  0,  camera.near,
+        0,  0,  -1, 0,
     };
     camera.matrix = Transform.multiplyMatrix(projection, camera.transform.inverseMatrix());
 }
@@ -61,9 +57,9 @@ pub fn mouse_in_quad(camera: Camera, mouse: @Vector(2, f32), quad_transform: Tra
     const hh = height * 0.5;
     const pi: [4]@Vector(2, f32) = .{
         .{ -hw, -hh },
-        .{ -hw,  hh },
-        .{  hw,  hh },
-        .{  hw, -hh },
+        .{ -hw, hh },
+        .{ hw, hh },
+        .{ hw, -hh },
     };
     var po: [4]@Vector(2, f32) = undefined;
     for (0..4) |i| {
diff --git a/src/graphics/presets.zig b/src/graphics/presets.zig
index d9673f0..e4e008b 100644
--- a/src/graphics/presets.zig
+++ b/src/graphics/presets.zig
@@ -12,7 +12,7 @@ pub const BLEND_NORMAL = sdl.GPUColorTargetBlendState{
 };
 
 pub const DEPTH_ENABLED = sdl.GPUDepthStencilState{
-    .compare_op = sdl.GPU_COMPAREOP_LESS,
+    .compare_op = sdl.GPU_COMPAREOP_GREATER,
     .enable_depth_test = true,
     .enable_depth_write = true,
 };
diff --git a/src/world.zig b/src/world.zig
index 950de95..670578a 100644
--- a/src/world.zig
+++ b/src/world.zig
@@ -459,7 +459,7 @@ pub fn draw() void {
     );
 
     Graphics.drawObject(&World.cubemap, .{
-        .scale = Graphics.camera.far,
+        .scale = 1e20,
         .position = Graphics.camera.transform.position,
     });
     Graphics.clearDepth();