From be6151730dac8a5f14887d4770285e885d944d2f Mon Sep 17 00:00:00 2001
From: Kovid Goyal <kovid@kovidgoyal.net>
Date: Thu, 23 Nov 2017 19:56:07 +0530
Subject: [PATCH] Fix SPECIAL stage in interleaved rendering

---
 kitty/cell_fragment.glsl |  4 ++--
 kitty/cell_vertex.glsl   | 18 ++++++++++++------
 kitty/shaders.c          |  4 +++-
 3 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/kitty/cell_fragment.glsl b/kitty/cell_fragment.glsl
index f58106dea..f1b07b9c7 100644
--- a/kitty/cell_fragment.glsl
+++ b/kitty/cell_fragment.glsl
@@ -12,7 +12,7 @@
 
 #ifdef NEEDS_BACKROUND
 in vec3 background;
-#ifdef TRANSPARENT
+#if defined(TRANSPARENT) || defined(SPECIAL)
 in float bg_alpha;
 #endif
 #endif
@@ -63,7 +63,7 @@ vec4 calculate_foreground() {
 
 void main() {
 #if defined(BACKGROUND) || defined(SPECIAL)
-#ifdef TRANSPARENT
+#if defined(TRANSPARENT) || defined(SPECIAL)
     final_color = vec4(background.rgb * bg_alpha, bg_alpha);
 #else
     final_color = vec4(background.rgb, 1.0f);
diff --git a/kitty/cell_vertex.glsl b/kitty/cell_vertex.glsl
index c628f5ce9..d0b800e00 100644
--- a/kitty/cell_vertex.glsl
+++ b/kitty/cell_vertex.glsl
@@ -41,7 +41,7 @@ const uvec2 cell_pos_map[] = uvec2[4](
 
 #ifdef NEEDS_BACKROUND
 out vec3 background;
-#ifdef TRANSPARENT
+#if defined(TRANSPARENT) || defined(SPECIAL)
 out float bg_alpha;
 #endif
 #endif
@@ -173,18 +173,24 @@ void main() {
 
 #if defined(BACKGROUND)
     background = bg;
-#else
-    // Selection and cursor
-    bg = choose_color(is_selected, color_to_vec(highlight_bg), bg);
-    background = choose_color(cursor, color_to_vec(cursor_color), bg);
 #endif
 
-#ifdef TRANSPARENT
+#if defined(TRANSPARENT) && !defined(SPECIAL)
     // If the background color is default, set its opacity to background_opacity, otherwise it should be opaque
     bg_alpha = step(0.5, float(colors[bg_index] & BYTE_MASK));
     bg_alpha = bg_alpha + (1.0f - bg_alpha) * background_opacity;
 #endif
 
+#if defined(SPECIAL) || defined(SIMPLE)
+    // Selection and cursor
+    bg = choose_color(is_selected, color_to_vec(highlight_bg), bg);
+    background = choose_color(cursor, color_to_vec(cursor_color), bg);
+#ifdef SPECIAL
+    // bg_alpha should be 1 if cursor/selection otherwise 0
+    bg_alpha = mix(0.0, 1.0, step(0.5, is_selected + cursor));
+#endif
+#endif
+
 #endif
     // }}}
 
diff --git a/kitty/shaders.c b/kitty/shaders.c
index e6e709b9b..0a9798c57 100644
--- a/kitty/shaders.c
+++ b/kitty/shaders.c
@@ -279,8 +279,8 @@ cell_prepare_to_render(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, GLfloa
 
 static void
 draw_graphics(int program, ssize_t vao_idx, ssize_t gvao_idx, ImageRenderData *data, GLuint start, GLuint count) {
-    bind_vertex_array(gvao_idx);
     bind_program(program);
+    bind_vertex_array(gvao_idx);
     static bool graphics_constants_set = false;
     if (!graphics_constants_set) { 
         glUniform1i(glGetUniformLocation(program_id(GRAPHICS_PROGRAM), "image"), GRAPHICS_UNIT);  
@@ -332,6 +332,7 @@ draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWind
     glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, screen->lines * screen->columns); 
     glEnable(GL_BLEND);
     glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);  // blending of pre-multiplied colors
+
     if (screen->grman->num_of_negative_refs) draw_graphics(GRAPHICS_PREMULT_PROGRAM, vao_idx, gvao_idx, screen->grman->render_data, 0, screen->grman->num_of_negative_refs);
 
     bind_program(CELL_SPECIAL_PROGRAM); 
@@ -341,6 +342,7 @@ draw_cells_interleaved(ssize_t vao_idx, ssize_t gvao_idx, Screen *screen, OSWind
     glDrawArraysInstanced(GL_TRIANGLE_FAN, 0, 4, screen->lines * screen->columns); 
 
     if (screen->grman->num_of_positive_refs) draw_graphics(GRAPHICS_PREMULT_PROGRAM, vao_idx, gvao_idx, screen->grman->render_data, screen->grman->num_of_negative_refs, screen->grman->num_of_positive_refs);
+
     glDisable(GL_BLEND);
     glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);