diff --git a/kitty/shaders/custom/bloom.slang b/kitty/shaders/custom/bloom.slang
index 1a65881d7..68e5d42f3 100644
--- a/kitty/shaders/custom/bloom.slang
+++ b/kitty/shaders/custom/bloom.slang
@@ -48,9 +48,7 @@ float lum(float4 c) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float2 uv = t.pos;
 
diff --git a/kitty/shaders/custom/crt.slang b/kitty/shaders/custom/crt.slang
index cd7dcad96..e38ab095d 100644
--- a/kitty/shaders/custom/crt.slang
+++ b/kitty/shaders/custom/crt.slang
@@ -16,9 +16,7 @@ static const float4 TINT = float4(0, 0.8, 0.6, 0);  // tint color set the fourth
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     // UV within the current viewport (0..1)
     float2 uv = t.pos;
@@ -32,13 +30,13 @@ public float4 fragment_main(
     uv.y -= 0.5f; uv.y *= 1.0f + (dc.x * (0.4f * WARP)); uv.y += 0.5f;
 
     // Original Y pixel coordinate within the viewport (for scanline phase)
-    float fragCoordY = (t.pos.y - viewport.y) * float(d.viewport_size_pixels.y);
+    float fragCoordY = (t.pos.y - t.viewport.y) * float(d.viewport_size_pixels.y);
 
     // Scanline darkness at this pixel row
     float apply = abs(sin(fragCoordY) * 0.25f * SCAN);
 
     // Sample the backbuffer at the warped viewport UV
-    float2 sample_uv = viewport.xy + uv * viewport.zw;
+    float2 sample_uv = t.viewport.xy + uv * t.viewport.zw;
     float3 col = t.backbuffer.Sample(sample_uv).rgb;
     // apply the tint
     col = lerp(col, col * TINT.rgb, TINT.a);
diff --git a/kitty/shaders/custom/cursor-trail-blaze.slang b/kitty/shaders/custom/cursor-trail-blaze.slang
index db64b4dbc..1dcff5c3c 100644
--- a/kitty/shaders/custom/cursor-trail-blaze.slang
+++ b/kitty/shaders/custom/cursor-trail-blaze.slang
@@ -72,9 +72,7 @@ static float movementVertexFactor(float2 a, float2 b) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     if (d.cursor_trail_color.a <= 0.0) return color;
 
@@ -85,7 +83,7 @@ public float4 fragment_main(
     if (easedProgress <= 0.0) return color;
 
     // Work in pixel space for correct aspect-ratio distance measurements.
-    float2 pixelDims = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims = float2(d.viewport_size_pixels) * t.viewport.zw;
     float2 px        = t.pos * pixelDims;
 
     // Current cursor rect in pixel space (edge: .x=left .y=right .z=top .w=bottom, y-up).
diff --git a/kitty/shaders/custom/cursor-trail-default.slang b/kitty/shaders/custom/cursor-trail-default.slang
index f94ec18c5..bc07738b6 100644
--- a/kitty/shaders/custom/cursor-trail-default.slang
+++ b/kitty/shaders/custom/cursor-trail-default.slang
@@ -32,9 +32,7 @@ bool inside_trail_quad(float2 uv, float2 c0, float2 c1, float2 c2, float2 c3) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float opacity = d.cursor_trail_color.a;
     if (opacity <= 0.0) return color;
diff --git a/kitty/shaders/custom/cursor-trail-lightning.slang b/kitty/shaders/custom/cursor-trail-lightning.slang
index c05363fc1..29c79f91e 100644
--- a/kitty/shaders/custom/cursor-trail-lightning.slang
+++ b/kitty/shaders/custom/cursor-trail-lightning.slang
@@ -87,14 +87,12 @@ static float forkDist(float2 p, float2 a, float2 b, float seed) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float age = clamp((d.timestamp - d.cursor_trail_change_time) / DURATION, 0.0, 1.0);
     if (age >= 1.0) return color;
 
-    float2 pixelDims = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims = float2(d.viewport_size_pixels) * t.viewport.zw;
 
     // Cursor centres in pixel space (edge: .x=left .y=right .z=top .w=bottom, y-up).
     float2 curCenter  = float2(
diff --git a/kitty/shaders/custom/fireworks-rockets.slang b/kitty/shaders/custom/fireworks-rockets.slang
index 55cb62a14..6ce46cddb 100644
--- a/kitty/shaders/custom/fireworks-rockets.slang
+++ b/kitty/shaders/custom/fireworks-rockets.slang
@@ -100,11 +100,9 @@ float3 drawFireworks(float time, float2 uv, float3 particolor, float seed) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
-    float2 pixelDims = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims = float2(d.viewport_size_pixels) * t.viewport.zw;
     float  aspect    = pixelDims.x / pixelDims.y;
 
     // Map to [-aspect, aspect] × [-1, 1] with y=1 at top (matching the original)
diff --git a/kitty/shaders/custom/fireworks.slang b/kitty/shaders/custom/fireworks.slang
index 10583c39a..d750b99d7 100644
--- a/kitty/shaders/custom/fireworks.slang
+++ b/kitty/shaders/custom/fireworks.slang
@@ -78,11 +78,9 @@ float3 rainbow(float3 c, float time) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
-    float2 pixelDims = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims = float2(d.viewport_size_pixels) * t.viewport.zw;
     float  aspect    = pixelDims.x / pixelDims.y;
     float  time      = fmod(d.timestamp, 3600.0f) * TIME_SCALE;
 
diff --git a/kitty/shaders/custom/focus-highlight.slang b/kitty/shaders/custom/focus-highlight.slang
index 0a3d3dbcb..031519f45 100644
--- a/kitty/shaders/custom/focus-highlight.slang
+++ b/kitty/shaders/custom/focus-highlight.slang
@@ -22,9 +22,7 @@ static const float INACTIVE_DIM = 0.3;
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float4 g = d.active_window_geometry;
     // Pass through unchanged if no active window geometry is known.
@@ -35,7 +33,7 @@ public float4 fragment_main(
     float2 winMax = g.xy + g.zw;
 
     // Effect strength decays from 1 at animation start to 0 at the end.
-    float strength = 1.0 - animation_progress;
+    float strength = 1.0 - t.animation_progress;
 
     bool inWindow = all(uv >= winMin) && all(uv <= winMax);
 
diff --git a/kitty/shaders/custom/inside-the-matrix.slang b/kitty/shaders/custom/inside-the-matrix.slang
index a6858db3f..02ee7b74e 100644
--- a/kitty/shaders/custom/inside-the-matrix.slang
+++ b/kitty/shaders/custom/inside-the-matrix.slang
@@ -237,9 +237,7 @@ float smoothstep1(float x) { return smoothstep(0.0f, 1.0f, x); }
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float2 uv   = t.pos;
     float  time = fmod(d.timestamp, 300.0f) * SPEED;
diff --git a/kitty/shaders/custom/negative.slang b/kitty/shaders/custom/negative.slang
index e1fdf99b4..4f0224a5c 100644
--- a/kitty/shaders/custom/negative.slang
+++ b/kitty/shaders/custom/negative.slang
@@ -9,9 +9,7 @@ import kitty_custom_shader_types;
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     return float4(1.0 - color.r, 1.0 - color.g, 1.0 - color.b, color.a);
 }
diff --git a/kitty/shaders/custom/pipeline.slang b/kitty/shaders/custom/pipeline.slang
index 9e48828dd..801ce5f0d 100644
--- a/kitty/shaders/custom/pipeline.slang
+++ b/kitty/shaders/custom/pipeline.slang
@@ -64,7 +64,7 @@ uniform Sampler2D backbuffer, a, b, persist;
 public float4 pipeline_fragment_main(float2 backbuffer_pos, int group, float4 viewport, float animation_progress, bool convert_to_srgb) {
     float4 color = backbuffer.Sample(backbuffer_pos);  // pre multiplied linear RGB
     color = float4(color.rgb / color.a, color.a);  // un pre multiplied color passed through pipeline
-    KittyTextures t = {backbuffer, a, b, persist, backbuffer_pos};
+    KittyTextures t = {backbuffer, a, b, persist, backbuffer_pos, viewport, animation_progress};
     // PIPELINE
     return vec4_premul(color.rgb, color.a);
 }
diff --git a/kitty/shaders/custom/pond-ripple.slang b/kitty/shaders/custom/pond-ripple.slang
index c22805374..cef48c99e 100644
--- a/kitty/shaders/custom/pond-ripple.slang
+++ b/kitty/shaders/custom/pond-ripple.slang
@@ -28,11 +28,9 @@ static const float DIFFUSE_STRENGTH  = 0.10;
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
-    float2 pixelDims = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims = float2(d.viewport_size_pixels) * t.viewport.zw;
     float  aspect    = pixelDims.x / pixelDims.y;
 
     // d.mouse_pos.zw is the UV position of the last left-button press (y=0 at bottom).
@@ -44,20 +42,20 @@ public float4 fragment_main(
     float2 dir   = delta / max(dist, 1e-5);
 
     // Wavefront radius advances linearly with animation_progress.
-    float front = WAVE_SPEED * animation_progress;
+    float front = WAVE_SPEED * t.animation_progress;
 
     // Signed distance from the wavefront (negative = wave has passed, positive = not yet reached).
     float behind = dist - front;
 
     // Gaussian spatial envelope centered at the wavefront; grows in width over time.
-    float sigma = WAVE_WIDTH * (1.0 + animation_progress);
+    float sigma = WAVE_WIDTH * (1.0 + t.animation_progress);
     float env   = exp(-behind * behind / (2.0 * sigma * sigma));
 
     // Causality: suppress any energy ahead of the wavefront.
     env *= 1.0 - smoothstep(-0.01, 0.02, behind);
 
     // Temporal amplitude decay as the wave expands outward.
-    float decay = pow(1.0 - animation_progress, 0.7);
+    float decay = pow(1.0 - t.animation_progress, 0.7);
 
     float k    = WAVE_FREQUENCY * 6.28318530718;
     float wave = sin(behind * k);
diff --git a/kitty/shaders/custom/sample.slang b/kitty/shaders/custom/sample.slang
index 51a4fb709..b6446c8af 100644
--- a/kitty/shaders/custom/sample.slang
+++ b/kitty/shaders/custom/sample.slang
@@ -13,18 +13,7 @@ public float4 fragment_main(
     KittyTextures t,
 
     // See types.slang for details on the data in this structure
-    KittyCustomShaderData d,
-
-    // The viewport used for this group. In the form (x, y, width, height)
-    // where (x, y) is the bottom-left corner of the viewport, with (0, 0) at
-    // the bottom-left of the screen and y increasing upwards (standard UV
-    // coordinates). All numbers are unit floats. If no viewport is defined for
-    // the group defaults to (0, 0, 1, 1) that is, the full backbuffer.
-    float4 viewport,
-
-    // The value after applying the animation easing curve to time since
-    // animation start.
-    float animation_progress
+    KittyCustomShaderData d
 )
 { // END_FUNCTION_SIGNATURE
     return float4(color.r, min(max(0.1, color.g) * 2, 1), color.b, color.a);
diff --git a/kitty/shaders/custom/spotlight.slang b/kitty/shaders/custom/spotlight.slang
index 61d3493cb..d283f8a0a 100644
--- a/kitty/shaders/custom/spotlight.slang
+++ b/kitty/shaders/custom/spotlight.slang
@@ -24,15 +24,13 @@ static const int   HIDE_WHEN_POINTER_HIDDEN = 1;
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     if (HIDE_WHEN_POINTER_HIDDEN == 1 && d.mouse_pointer_hidden != 0.0) return color;
     float2 uv = t.pos;
 
     // Viewport pixel dimensions for aspect-ratio correction
-    float2 pixelDims   = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 pixelDims   = float2(d.viewport_size_pixels) * t.viewport.zw;
     float  aspectRatio = pixelDims.x / pixelDims.y;
 
     // Random oscillating center (different frequencies and phases on each axis)
diff --git a/kitty/shaders/custom/tab-change.slang b/kitty/shaders/custom/tab-change.slang
index d60c4e00d..a5532bba0 100644
--- a/kitty/shaders/custom/tab-change.slang
+++ b/kitty/shaders/custom/tab-change.slang
@@ -54,14 +54,12 @@ float wipe_pixel_pos(float2 uv, float4 ca) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float4 ca = d.central_area;
     if (ca.z <= 0.0 || ca.w <= 0.0) return color;
 
-    float p = animation_progress;
+    float p = t.animation_progress;
     float brightness;
 
     if (ANIMATION_TYPE == 0) {
diff --git a/kitty/shaders/custom/tft.slang b/kitty/shaders/custom/tft.slang
index 9b62cff99..eae38713f 100644
--- a/kitty/shaders/custom/tft.slang
+++ b/kitty/shaders/custom/tft.slang
@@ -21,9 +21,7 @@ void scanline(inout float3 color, float2 pixel_pos) {
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float2 pixel_pos = t.pos * float2(d.viewport_size_pixels);
     float3 c = color.rgb;
diff --git a/kitty/shaders/custom/types.slang b/kitty/shaders/custom/types.slang
index c86a709f5..d9d8c8bf1 100644
--- a/kitty/shaders/custom/types.slang
+++ b/kitty/shaders/custom/types.slang
@@ -52,8 +52,8 @@ public struct KittyCustomShaderData {
 
     // the size in pixels of the full underlying viewport we are rendering too,
     // before applying any viewport transforms from the current group.
-    // You can use the viewport vector passed to fragment_main to derive the
-    // actual size and position of the viewport currently being rendered too.
+    // You can use t.viewport to derive the actual size and position of the
+    // viewport currently being rendered too.
     public uint2 viewport_size_pixels;
 
     public float mouse_pointer_hidden;  // 1.0 if the mouse pointer is currently hidden, 0.0 if visible
@@ -80,5 +80,13 @@ public struct KittyTextures {
     public Sampler2D persist;
 
     public float2 pos;  // the position of this pixel in the textures (UV coordinates)
+
+    // The viewport for this group in the form (x, y, width, height) where (x, y) is the
+    // bottom-left corner, with (0, 0) at the bottom-left of the screen and y increasing upwards
+    // (UV coordinates). Defaults to (0, 0, 1, 1) when no viewport is defined for the group.
+    public float4 viewport;
+    // The value after applying the animation easing curve to time since animation start.
+    // Zero when no animation is active.
+    public float animation_progress;
 }
 // END_TYPES_DEFINITION
diff --git a/kitty/shaders/custom/underwater.slang b/kitty/shaders/custom/underwater.slang
index 427a253fa..d1f8fe7de 100644
--- a/kitty/shaders/custom/underwater.slang
+++ b/kitty/shaders/custom/underwater.slang
@@ -65,11 +65,9 @@ float rayStrength(
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
-    float2 iResolution = float2(d.viewport_size_pixels) * viewport.zw;
+    float2 iResolution = float2(d.viewport_size_pixels) * t.viewport.zw;
     float  iTime       = d.timestamp;
 
     // Convert kitty UV (y=0 at bottom) to a top-left-origin pixel coordinate,
diff --git a/kitty/shaders/custom/water.slang b/kitty/shaders/custom/water.slang
index d0e219757..5a0ba4dd1 100644
--- a/kitty/shaders/custom/water.slang
+++ b/kitty/shaders/custom/water.slang
@@ -15,9 +15,7 @@ static const float  UV_DISPLACEMENT = 0.04;                   // UV warp magnitu
 public float4 fragment_main(
     float4 color,
     KittyTextures t,
-    KittyCustomShaderData d,
-    float4 viewport,
-    float animation_progress
+    KittyCustomShaderData d
 ) {
     float  wtime = d.timestamp * 0.5 + 23.0;
     float2 uv    = t.pos;
diff --git a/kitty/shaders/slang.py b/kitty/shaders/slang.py
index fb2dbe9a4..70f7bef5e 100644
--- a/kitty/shaders/slang.py
+++ b/kitty/shaders/slang.py
@@ -1410,7 +1410,7 @@ def build_custom_shader_pipeline_ir(pipeline: Pipeline, cache_dir: str, invocati
     # inactive animated groups do not cause an extra blit draw call.
     pipeline_parts: list[str] = []
     for g_idx, group in enumerate(pipeline['groups']):
-        calls = '\n'.join(f'        color = {entry_point(g_idx, j)}(color, t, csd, viewport, animation_progress);' for j in range(len(group['shaders'])))
+        calls = '\n'.join(f'        color = {entry_point(g_idx, j)}(color, t, csd);' for j in range(len(group['shaders'])))
         calls += '\n        if (convert_to_srgb) color = float4(linear2srgb(color.rgb), color.a);'
         prefix = '} else ' if g_idx else ''
         pipeline_parts.append(f'    {prefix}if (group == {g_idx}) {{\n{calls}')