Get rid of transparency specialisation in cell shader

It's not a significant optimisation anymore as it only
elides call to adjust_alpha_for_incorrect_blending_by_compositor,
which will probably not be needed anymore anyway.

kitty/cell_defines.glsl

@@ -1,4 +1,3 @@
-#define HAS_TRANSPARENCY {TRANSPARENT}
 #define DO_FG_OVERRIDE {DO_FG_OVERRIDE}
 #define FG_OVERRIDE_THRESHOLD {FG_OVERRIDE_THRESHOLD}
 #define FG_OVERRIDE_ALGO {FG_OVERRIDE_ALGO}
@@ -13,9 +12,5 @@
 #define USE_SELECTION_FG
 #define NUM_COLORS 256
 
-#if (HAS_TRANSPARENCY == 1)
-#define TRANSPARENT
-#endif
-
 // sRGB luminance values
 const vec3 Y = vec3(0.2126, 0.7152, 0.0722);

kitty/cell_fragment.glsl

@@ -112,11 +112,7 @@ void main() {
     vec4 text_fg = load_text_foreground_color();
     text_fg = adjust_foreground_contrast_with_background(text_fg, background);
     vec4 text_fg_premul = calculate_premul_foreground_from_sprites(text_fg);
-#ifdef TRANSPARENT
     final_color = alpha_blend_premul(text_fg_premul, vec4_premul(background, bg_alpha));
     final_color.a = adjust_alpha_for_incorrect_blending_by_compositor(text_fg_premul.a, final_color.a);
-#else
-    final_color = alpha_blend_premul(text_fg_premul, background);
-#endif
     output_color = final_color;
 }

kitty/fast_data_types.pyi

@@ -604,7 +604,7 @@ def create_os_window(
     wm_class_name: str,
     wm_class_class: str,
     window_state: Optional[int] = WINDOW_NORMAL,
-    load_programs: Optional[Callable[[bool], None]] = None,
+    load_programs: Optional[Callable[[], None]] = None,
     x: Optional[int] = None,
     y: Optional[int] = None,
     disallow_override_title: bool = False,

kitty/glfw.c

@@ -1487,7 +1487,7 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
         }
     }
     if (is_first_window) {
-        PyObject *ret = PyObject_CallFunction(load_programs, "O", is_semi_transparent ? Py_True : Py_False);
+        PyObject *ret = PyObject_CallNoArgs(load_programs);
         if (ret == NULL) return NULL;
         Py_DECREF(ret);
         get_platform_dependent_config_values(glfw_window);
@@ -1495,7 +1495,6 @@ create_os_window(PyObject UNUSED *self, PyObject *args, PyObject *kw) {
         glGetFramebufferAttachmentParameteriv(GL_FRAMEBUFFER, GL_BACK_LEFT, GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING, &encoding);
         if (encoding != GL_SRGB) log_error("The output buffer does not support sRGB color encoding, colors will be incorrect.");
         is_first_window = false;
-
     }
     OSWindow *w = add_os_window();
     w->handle = glfw_window;

kitty/main.py

@@ -86,9 +86,9 @@ def set_custom_ibeam_cursor() -> None:
         log_error(f'Failed to set custom beam cursor with error: {e}')
 
 
-def load_all_shaders(semi_transparent: bool = False) -> None:
+def load_all_shaders() -> None:
     try:
-        load_shader_programs(semi_transparent)
+        load_shader_programs()
         load_borders_program()
     except CompileError as err:
         raise SystemExit(err)

kitty/shaders.c

@@ -16,9 +16,9 @@
 
 /*
  * TODO: for shader refactoring
- * Get rid of TRANSPARENT define and always use premul colors
  * Change rendering of cursor -- should now be rendered with full blending as a layer between bg and fg layers
  * Check that rendering of special cells aka selections still works
+ * Check color fringing issues and background lightness isssues are properly fixed
  * Port graphics rendering to start use a dummy 1 pixel empty texture then possibly replace with defines so that the most
  * common use case of no graphics has zero performance overhead.
  * Convert all images loaded to GPU to linear space for correct blending or alternately do conversion to linear space in

kitty/shaders.py

@@ -136,7 +136,6 @@ class TextFgOverrideThreshold(NamedTuple):
 class LoadShaderPrograms:
     text_fg_override_threshold: TextFgOverrideThreshold = TextFgOverrideThreshold()
     text_old_gamma: bool = False
-    semi_transparent: bool = False
     cell_program_replacer: MultiReplacer = null_replacer
 
     @property
@@ -149,10 +148,9 @@ class LoadShaderPrograms:
 
     def recompile_if_needed(self) -> None:
         if self.needs_recompile:
-            self(self.semi_transparent, allow_recompile=True)
+            self(allow_recompile=True)
 
-    def __call__(self, semi_transparent: bool = False, allow_recompile: bool = False) -> None:
-        self.semi_transparent = semi_transparent
+    def __call__(self, allow_recompile: bool = False) -> None:
         opts = get_options()
         self.text_old_gamma = opts.text_composition_strategy == 'legacy'
 
@@ -179,7 +177,6 @@ class LoadShaderPrograms:
 
         def resolve_cell_defines(src: str) -> str:
             r = self.cell_program_replacer.replacements
-            r['TRANSPARENT'] = '1' if semi_transparent else '0'
             r['DO_FG_OVERRIDE'] = '1' if self.text_fg_override_threshold.scaled_value else '0'
             r['FG_OVERRIDE_ALGO'] = '1' if self.text_fg_override_threshold.unit == '%' else '2'
             r['FG_OVERRIDE_THRESHOLD'] = str(self.text_fg_override_threshold.scaled_value)