From 8c01f7fafff2385275eb3b94f2cf7afa75319468 Mon Sep 17 00:00:00 2001
From: rdb <git@rdb.name>
Date: Mon, 30 Aug 2021 14:02:41 +0200
Subject: [PATCH] gles2gsg: Implement support for GL_EXT_clear_texture in
 OpenGL ES 2+

---
 panda/src/gles2gsg/panda_esgl2ext.h               | 10 ++++++++++
 panda/src/glstuff/glGraphicsStateGuardian_src.cxx | 12 ++++++++++++
 panda/src/glstuff/glGraphicsStateGuardian_src.h   |  6 +++---
 3 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/panda/src/gles2gsg/panda_esgl2ext.h b/panda/src/gles2gsg/panda_esgl2ext.h
index 888e8e2553..a95d9b001b 100644
--- a/panda/src/gles2gsg/panda_esgl2ext.h
+++ b/panda/src/gles2gsg/panda_esgl2ext.h
@@ -1050,6 +1050,16 @@ GL_APICALL void GL_APIENTRY glBufferStorageEXT (GLenum target, GLsizeiptr size,
 #endif
 #endif /* GL_EXT_buffer_storage */
 
+#ifndef GL_EXT_clear_texture
+#define GL_EXT_clear_texture 1
+typedef void (GL_APIENTRYP PFNGLCLEARTEXIMAGEEXTPROC) (GLuint texture, GLint level, GLenum format, GLenum type, const void *data);
+typedef void (GL_APIENTRYP PFNGLCLEARTEXSUBIMAGEEXTPROC) (GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const void *data);
+#ifdef GL_GLEXT_PROTOTYPES
+GL_APICALL void GL_APIENTRY glClearTexImageEXT (GLuint texture, GLint level, GLenum format, GLenum type, const void *data);
+GL_APICALL void GL_APIENTRY glClearTexSubImageEXT (GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const void *data);
+#endif
+#endif /* GL_EXT_clear_texture */
+
 #ifndef GL_EXT_clip_control
 #define GL_EXT_clip_control 1
 #define GL_LOWER_LEFT_EXT                 0x8CA1
diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
index 2bbeff7665..8aba915666 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.cxx
@@ -1080,6 +1080,18 @@ reset() {
       _supports_clear_texture = true;
     }
   }
+#elif !defined(OPENGLES_1)
+  if (has_extension("GL_EXT_clear_texture")) {
+    _glClearTexImage = (PFNGLCLEARTEXIMAGEEXTPROC)
+      get_extension_func("glClearTexImageEXT");
+
+    if (_glClearTexImage == nullptr) {
+      GLCAT.warning()
+        << "GL_EXT_clear_texture advertised as supported by OpenGL runtime, but could not get pointers to extension function.\n";
+    } else {
+      _supports_clear_texture = true;
+    }
+  }
 #endif
 
   _supports_clear_buffer = false;
diff --git a/panda/src/glstuff/glGraphicsStateGuardian_src.h b/panda/src/glstuff/glGraphicsStateGuardian_src.h
index c889545fc9..6457cc920c 100644
--- a/panda/src/glstuff/glGraphicsStateGuardian_src.h
+++ b/panda/src/glstuff/glGraphicsStateGuardian_src.h
@@ -229,10 +229,10 @@ typedef void (APIENTRYP PFNGLPROGRAMBINARYPROC) (GLuint program, GLenum binaryFo
 typedef void (APIENTRYP PFNGLGETINTERNALFORMATIVPROC) (GLenum target, GLenum internalformat, GLenum pname, GLsizei bufSize, GLint *params);
 typedef void (APIENTRYP PFNGLBUFFERSTORAGEPROC) (GLenum target, GLsizeiptr size, const void *data, GLbitfield flags);
 typedef void (APIENTRYP PFNGLBINDIMAGETEXTUREPROC) (GLuint unit, GLuint texture, GLint level, GLboolean layered, GLint layer, GLenum access, GLenum format);
-#endif  // OPENGLES_1
-#ifndef OPENGLES
 typedef void (APIENTRYP PFNGLCLEARTEXIMAGEPROC) (GLuint texture, GLint level, GLenum format, GLenum type, const void *data);
 typedef void (APIENTRYP PFNGLCLEARTEXSUBIMAGEPROC) (GLuint texture, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const void *data);
+#endif  // OPENGLES_1
+#ifndef OPENGLES
 typedef void (APIENTRYP PFNGLBINDTEXTURESPROC) (GLuint first, GLsizei count, const GLuint *textures);
 typedef void (APIENTRYP PFNGLBINDSAMPLERSPROC) (GLuint first, GLsizei count, const GLuint *samplers);
 typedef void (APIENTRYP PFNGLBINDIMAGETEXTURESPROC) (GLuint first, GLsizei count, const GLuint *textures);
@@ -804,7 +804,7 @@ public:
 #endif
 
   bool _supports_clear_texture;
-#ifndef OPENGLES
+#ifndef OPENGLES_1
   PFNGLCLEARTEXIMAGEPROC _glClearTexImage;
 #endif