From fdb130651de99cbe67116351808c91e09c08c014 Mon Sep 17 00:00:00 2001
From: Bartosz Taudul <wolf@nereid.pl>
Date: Sat, 15 Oct 2022 12:56:19 +0200
Subject: Detect if hardware supports S3TC.

---
 profiler/src/main.cpp   |  1 +
 server/TracyTexture.cpp | 28 +++++++++++++++++++++++++++-
 server/TracyTexture.hpp |  1 +
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/profiler/src/main.cpp b/profiler/src/main.cpp
index 6035b590..a579564b 100644
--- a/profiler/src/main.cpp
+++ b/profiler/src/main.cpp
@@ -221,6 +221,7 @@ int main( int argc, char** argv )
 
     ImGuiTracyContext imguiContext;
     Backend backend( title, DrawContents, &mainThreadTasks );
+    tracy::InitTexture();
     iconTex = tracy::MakeTexture();
     iconThread.join();
     backend.SetIcon( iconPx, iconX, iconY );
diff --git a/server/TracyTexture.cpp b/server/TracyTexture.cpp
index 1fa748c2..dd07751f 100644
--- a/server/TracyTexture.cpp
+++ b/server/TracyTexture.cpp
@@ -1,6 +1,7 @@
 #include <inttypes.h>
 
 #ifdef __EMSCRIPTEN__
+#  include <emscripten/html5.h>
 #  include <GLES2/gl2.h>
 #else
 #  include "../profiler/src/imgui/imgui_impl_opengl3_loader.h"
@@ -14,6 +15,28 @@
 namespace tracy
 {
 
+static bool s_hardwareS3tc;
+
+void InitTexture()
+{
+#ifdef __EMSCRIPTEN__
+    s_hardwareS3tc = emscripten_webgl_enable_extension( emscripten_webgl_get_current_context(), "WEBGL_compressed_texture_s3tc" );
+#else
+    s_hardwareS3tc = false;
+    GLint num;
+    glGetIntegerv( GL_NUM_EXTENSIONS, &num );
+    for( GLint i=0; i<num; i++ )
+    {
+        auto ext = (const char*)glGetStringi( GL_EXTENSIONS, GLuint( i ) );
+        if( strcmp( ext, "GL_EXT_texture_compression_s3tc" ) == 0 )
+        {
+            s_hardwareS3tc = true;
+            break;
+        }
+    }
+#endif
+}
+
 void* MakeTexture()
 {
     GLuint tex;
@@ -36,7 +59,10 @@ void UpdateTexture( void* _tex, const char* data, int w, int h )
 {
     auto tex = (GLuint)(intptr_t)_tex;
     glBindTexture( GL_TEXTURE_2D, tex );
-    glCompressedTexImage2D( GL_TEXTURE_2D, 0, COMPRESSED_RGB_S3TC_DXT1_EXT, w, h, 0, w * h / 2, data );
+    if( s_hardwareS3tc )
+    {
+        glCompressedTexImage2D( GL_TEXTURE_2D, 0, COMPRESSED_RGB_S3TC_DXT1_EXT, w, h, 0, w * h / 2, data );
+    }
 }
 
 void UpdateTextureRGBA( void* _tex, void* data, int w, int h )
diff --git a/server/TracyTexture.hpp b/server/TracyTexture.hpp
index 128834da..bcc8a455 100644
--- a/server/TracyTexture.hpp
+++ b/server/TracyTexture.hpp
@@ -6,6 +6,7 @@
 namespace tracy
 {
 
+void InitTexture();
 void* MakeTexture();
 void FreeTexture( void* tex, void(*runOnMainThread)(std::function<void()>, bool) );
 void UpdateTexture( void* tex, const char* data, int w, int h );
-- 
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