From ea250ff5c57301b6ea3e529c811484c743c1fde1 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Fri, 10 Sep 2021 21:59:29 +0200
Subject: Fix GLES2 discard behaviour (texture transparency)

---
 client/shaders/nodes_shader/opengl_fragment.glsl  | 9 ++++++---
 client/shaders/object_shader/opengl_fragment.glsl | 9 ++++++---
 src/client/shader.cpp                             | 8 ++++++--
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/client/shaders/nodes_shader/opengl_fragment.glsl b/client/shaders/nodes_shader/opengl_fragment.glsl
index f85ca7b48..87ef9af7d 100644
--- a/client/shaders/nodes_shader/opengl_fragment.glsl
+++ b/client/shaders/nodes_shader/opengl_fragment.glsl
@@ -463,13 +463,16 @@ void main(void)
 	vec2 uv = varTexCoord.st;
 
 	vec4 base = texture2D(baseTexture, uv).rgba;
-#ifdef USE_DISCARD
 	// If alpha is zero, we can just discard the pixel. This fixes transparency
 	// on GPUs like GC7000L, where GL_ALPHA_TEST is not implemented in mesa,
 	// and also on GLES 2, where GL_ALPHA_TEST is missing entirely.
-	if (base.a == 0.0) {
+#ifdef USE_DISCARD
+	if (base.a == 0.0)
+		discard;
+#endif
+#ifdef USE_DISCARD_REF
+	if (base.a < 0.5)
 		discard;
-	}
 #endif
 
 	color = base.rgb;
diff --git a/client/shaders/object_shader/opengl_fragment.glsl b/client/shaders/object_shader/opengl_fragment.glsl
index 8d6f57a44..9a0b90f15 100644
--- a/client/shaders/object_shader/opengl_fragment.glsl
+++ b/client/shaders/object_shader/opengl_fragment.glsl
@@ -328,13 +328,16 @@ void main(void)
 	vec2 uv = varTexCoord.st;
 	vec4 base = texture2D(baseTexture, uv).rgba;
 
-#ifdef USE_DISCARD
 	// If alpha is zero, we can just discard the pixel. This fixes transparency
 	// on GPUs like GC7000L, where GL_ALPHA_TEST is not implemented in mesa,
 	// and also on GLES 2, where GL_ALPHA_TEST is missing entirely.
-	if (base.a == 0.0) {
+#ifdef USE_DISCARD
+	if (base.a == 0.0)
+		discard;
+#endif
+#ifdef USE_DISCARD_REF
+	if (base.a < 0.5)
 		discard;
-	}
 #endif
 
 	color = base.rgb;
diff --git a/src/client/shader.cpp b/src/client/shader.cpp
index 0b35c37af..dc9e9ae6d 100644
--- a/src/client/shader.cpp
+++ b/src/client/shader.cpp
@@ -674,8 +674,12 @@ ShaderInfo ShaderSource::generateShader(const std::string &name,
 	if (strstr(gl_renderer, "GC7000"))
 		use_discard = true;
 #endif
-	if (use_discard && shaderinfo.base_material != video::EMT_SOLID)
-		shaders_header << "#define USE_DISCARD 1\n";
+	if (use_discard) {
+		if (shaderinfo.base_material == video::EMT_TRANSPARENT_ALPHA_CHANNEL)
+			shaders_header << "#define USE_DISCARD 1\n";
+		else if (shaderinfo.base_material == video::EMT_TRANSPARENT_ALPHA_CHANNEL_REF)
+			shaders_header << "#define USE_DISCARD_REF 1\n";
+	}
 
 #define PROVIDE(constant) shaders_header << "#define " #constant " " << (int)constant << "\n"
 
-- 
cgit v1.2.3