From bbf293240fbd6d3be94f1971ed779ce398e3ba3d Mon Sep 17 00:00:00 2001
From: "Carsten Haitzler (Rasterman)" <raster@rasterman.com>
Date: Fri, 2 Apr 2021 23:28:38 +0100
Subject: [PATCH] evas gl - add env var to disable dither because some gl's are
 broken

this adds a

EVAS_GL_RENDER_DISABLE_DITHER=1

env var (set it to anything) to disable dithered rendering.p this is
an added cost, but normally not much at all, but it seems some gl
implementations are broken, and they can't generate correct code for
the dither shader, so this disables this if this env var above is set
---
 .../evas/engines/gl_common/evas_gl_shader.c   | 35 +++++++++++++------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/src/modules/evas/engines/gl_common/evas_gl_shader.c b/src/modules/evas/engines/gl_common/evas_gl_shader.c
index 489ea3d8c5..b3802f2c70 100644
--- a/src/modules/evas/engines/gl_common/evas_gl_shader.c
+++ b/src/modules/evas/engines/gl_common/evas_gl_shader.c
@@ -84,6 +84,7 @@ static const char *_shader_flags[SHADER_FLAG_COUNT] = {
 };
 
 static Eina_Bool compiler_released = EINA_FALSE;
+static Eina_Bool _do_dither = EINA_TRUE;
 
 static void
 gl_compile_link_error(GLuint target, const char *action, Eina_Bool is_shader)
@@ -553,17 +554,18 @@ evas_gl_common_shader_precompile_list(Evas_GL_Shared *shared)
 {
    int bgra, mask, sam, masksam, img, nomul, afill, yuv;
    Eina_List *li = NULL;
+   unsigned int baseflags = 0;
 
    if (!shared) return NULL;
-
+   if (_do_dither) baseflags |= BASEFLAG;
    // rect
-   li = eina_list_append(li, P(BASEFLAG));
+   li = eina_list_append(li, P(baseflags));
 
    // text
    for (mask = 0; mask <= 1; mask++)
      for (masksam = SHD_SAM11; masksam < (mask ? SHD_SAM_LAST : 1); masksam++)
        {
-          int           flags  = BASEFLAG | SHADER_FLAG_TEX | SHADER_FLAG_ALPHA;
+          int           flags  = baseflags | SHADER_FLAG_TEX | SHADER_FLAG_ALPHA;
           if (mask)     flags |= SHADER_FLAG_MASK;
           if (masksam)  flags |= (1 << (SHADER_FLAG_MASKSAM_BITSHIFT + masksam - 1));
           li = eina_list_append(li, P(flags));
@@ -578,7 +580,7 @@ evas_gl_common_shader_precompile_list(Evas_GL_Shared *shared)
              for (nomul = 0; nomul <= 1; nomul++)
                for (afill = 0; afill <= (mask ? 0 : 1); afill++)
                  {
-                    int           flags  = BASEFLAG | SHADER_FLAG_TEX;
+                    int           flags  = baseflags | SHADER_FLAG_TEX;
                     if (mask)     flags |= SHADER_FLAG_MASK;
                     if (masksam)  flags |= (1 << (SHADER_FLAG_MASKSAM_BITSHIFT + masksam - 1));
                     if (sam)      flags |= (1 << (SHADER_FLAG_SAM_BITSHIFT + sam - 1));
@@ -595,7 +597,7 @@ evas_gl_common_shader_precompile_list(Evas_GL_Shared *shared)
        for (masksam = SHD_SAM11; masksam < (mask ? SHD_SAM_LAST : 1); masksam++)
          for (nomul = 0; nomul <= 1; nomul++)
            {
-              int           flags  = BASEFLAG | SHADER_FLAG_TEX | yuv;
+              int           flags  = baseflags | SHADER_FLAG_TEX | yuv;
               if (mask)     flags |= SHADER_FLAG_MASK;
               if (masksam)  flags |= (1 << (SHADER_FLAG_MASKSAM_BITSHIFT + masksam - 1));
               if (yuv == SHADER_FLAG_YUV_709) flags |= SHADER_FLAG_YUV;
@@ -666,15 +668,25 @@ evas_gl_common_shader_program_init(Evas_GL_Shared *shared)
 {
    /* most popular shaders */
    const int BGRA = (shared->info.bgra ? SHADER_FLAG_BGRA : 0);
-   const int autoload[] = {
-      /* rect */ BASEFLAG,
-      /* text */ BASEFLAG | SHADER_FLAG_TEX | SHADER_FLAG_ALPHA,
-      /* img1 */ BASEFLAG | SHADER_FLAG_TEX | SHADER_FLAG_IMG | BGRA,
-      /* img2 */ BASEFLAG | SHADER_FLAG_TEX | SHADER_FLAG_IMG | SHADER_FLAG_NOMUL | BGRA,
+   unsigned int autoload[] = {
+      /* rect */ 0,
+      /* text */ 0 | SHADER_FLAG_TEX | SHADER_FLAG_ALPHA,
+      /* img1 */ 0 | SHADER_FLAG_TEX | SHADER_FLAG_IMG | BGRA,
+      /* img2 */ 0 | SHADER_FLAG_TEX | SHADER_FLAG_IMG | SHADER_FLAG_NOMUL | BGRA,
    };
    Evas_GL_Program *p;
    unsigned i;
 
+   if (getenv("EVAS_GL_RENDER_DISABLE_DITHER"))
+     _do_dither = EINA_FALSE;
+
+   if (_do_dither)
+     {
+        autoload[0] |= BASEFLAG;
+        autoload[1] |= BASEFLAG;
+        autoload[2] |= BASEFLAG;
+        autoload[3] |= BASEFLAG;
+     }
    shared->shaders_hash = eina_hash_int32_new(_shaders_hash_free_cb);
    if (_evas_gl_common_shader_binary_init(shared))
      {
@@ -770,8 +782,9 @@ evas_gl_common_shader_flags_get(Evas_GL_Shared *shared, Shader_Type type,
 {
    Shader_Sampling sam = SHD_SAM11, masksam = SHD_SAM11;
    int nomul = 1, bgra = 0, k;
-   unsigned int flags = BASEFLAG;
+   unsigned int flags = 0;
 
+   if (_do_dither) flags |= BASEFLAG;
    // image downscale sampling
    if (smooth && ((type == SHD_IMAGE) || (type == SHD_IMAGENATIVE)))
      {