fix #33188 MSAA depth buffer not used for external texture

When rendering to an external texture and MSAA was active (as happened
in the Oculus Mobile ARVR plugin) no MSAA was rendered as the correct
depth buffer and multisample texture target was not used.
This also fixes https://github.com/GodotVR/godot_oculus_mobile/issues/54

drivers/gles2/rasterizer_storage_gles2.cpp

@@ -5156,14 +5156,26 @@ void RasterizerStorageGLES2::render_target_set_external_texture(RID p_render_tar
 
 		// is there a point to setting the internal formats? we don't know them..
 
-		// set our texture as the destination for our framebuffer
-		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, p_texture_id, 0);
-
-		// seeing we're rendering into this directly, better also use our depth buffer, just use our existing one :)
-		if (config.support_depth_texture) {
-			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, rt->depth, 0);
+		// check if MSAA is active to set the correct depth buffer and target texture for android
+		if (rt->multisample_active) {
+#if defined(GLES_OVER_GL) || defined(IPHONE_ENABLED)
+			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, p_texture_id);
+#elif ANDROID_ENABLED
+			static const int msaa_value[] = { 0, 2, 4, 8, 16 };
+			int msaa = msaa_value[rt->msaa];
+			glFramebufferTexture2DMultisample(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, p_texture_id, 0, msaa);
+#endif
+			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rt->multisample_depth);
 		} else {
-			glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rt->depth);
+			// set our texture as the destination for our framebuffer
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, p_texture_id, 0);
+
+			// seeing we're rendering into this directly, better also use our depth buffer, just use our existing one :)
+			if (config.support_depth_texture) {
+				glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, rt->depth, 0);
+			} else {
+				glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, rt->depth);
+			}
 		}
 
 		// check status and unbind