From 3f8b2184a6081c616378e34452c5dba9a47f2620 Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Fri, 13 Oct 2017 10:06:12 +0530
Subject: [PATCH] Add a sanity check to ensure the attribute location binding
 worked

---
 kitty/cell_vertex.glsl     | 8 ++++----
 kitty/graphics_vertex.glsl | 2 +-
 kitty/shaders.c            | 8 ++++++++
 kitty/window.py            | 2 +-
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/kitty/cell_vertex.glsl b/kitty/cell_vertex.glsl
index 55117a9bc..f772099a7 100644
--- a/kitty/cell_vertex.glsl
+++ b/kitty/cell_vertex.glsl
@@ -13,10 +13,10 @@ layout(std140) uniform CellRenderData {
 };
 
 // Have to use fixed locations here as all variants of the cell program share the same VAO
-// locations after 2 are used in the graphics program which also shares the same VAO
-layout(location=0) in uvec3 colors;
-layout(location=1) in uvec4 sprite_coords;
-layout(location=2) in float is_selected;
+// location 0 is used in the graphics program which uses the same VAO
+layout(location=1) in uvec3 colors;
+layout(location=2) in uvec4 sprite_coords;
+layout(location=3) in float is_selected;
 
 #if defined(FOREGROUND) || defined(ALL)
 
diff --git a/kitty/graphics_vertex.glsl b/kitty/graphics_vertex.glsl
index 9345339b4..8fe913fb3 100644
--- a/kitty/graphics_vertex.glsl
+++ b/kitty/graphics_vertex.glsl
@@ -1,6 +1,6 @@
 #version GLSL_VERSION
 
-layout(location=3) in vec4 src;
+layout(location=0) in vec4 src;
 out vec2 texcoord;
 
 void main() {
diff --git a/kitty/shaders.c b/kitty/shaders.c
index a4ca95e6f..d1de716ba 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -191,6 +191,14 @@ init_cell_program() {
         cell_program_layouts[i].color_table.offset = get_uniform_information(i, "color_table[0]", GL_UNIFORM_OFFSET);
         cell_program_layouts[i].color_table.stride = get_uniform_information(i, "color_table[0]", GL_UNIFORM_ARRAY_STRIDE);
     }
+    // Sanity check to ensure the attribute location binding worked
+#define C(p, name, expected) { int aloc = attrib_location(p, #name); if (aloc != expected && aloc != -1) fatal("The attribute location for %s is %d != %d in program: %d", #name, aloc, expected, p); }
+    for (int p = CELL_PROGRAM; p <= CELL_FOREGROUND_PROGRAM; p++) {
+        C(p, colors, 1); C(p, sprite_coords, 2); C(p, is_selected, 3);
+    }
+    C(GRAPHICS_PROGRAM, src, 0);
+#undef C
+
 }
 
 #define CELL_BUFFERS enum { cell_data_buffer, selection_buffer, uniform_buffer, graphics_buffer };
diff --git a/kitty/window.py b/kitty/window.py
index fa1f1222d..f187f3447 100644
--- a/kitty/window.py
+++ b/kitty/window.py
@@ -53,6 +53,7 @@ def calculate_gl_geometry(window_geometry, viewport_width, viewport_height, cell
 
 def load_shader_programs():
     v, f = load_shaders('cell')
+    compile_program(GRAPHICS_PROGRAM, *load_shaders('graphics'))
     for which, p in {
             'ALL': CELL_PROGRAM, 'BACKGROUND': CELL_BACKGROUND_PROGRAM, 'SPECIAL': CELL_SPECIAL_PROGRAM,
             'FOREGROUND': CELL_FOREGROUND_PROGRAM
@@ -62,7 +63,6 @@ def load_shader_programs():
     init_cell_program()
     compile_program(CURSOR_PROGRAM, *load_shaders('cursor'))
     init_cursor_program()
-    compile_program(GRAPHICS_PROGRAM, *load_shaders('graphics'))
 
 
 class Window: