Android support for the OpenGL 3 backend (#840)

Backends/RmlUi_Backend_SDL_GL3.cpp

@@ -160,18 +160,24 @@ bool Backend::Initialize(const char* window_name, int width, int height, bool al
 	SDL_SetHint(SDL_HINT_MOUSE_TOUCH_EVENTS, "1");
 #endif
 
-#if defined RMLUI_PLATFORM_EMSCRIPTEN
-	// GLES 3.0 (WebGL 2.0)
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+#if defined(RMLUI_PLATFORM_EMSCRIPTEN)
+    // GLES 3.0 (WebGL 2.0)
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+#elif defined(__ANDROID__)
+    // GLES 3.2 on Android
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_ES);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 2);
 #else
-	// GL 3.3 Core
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
-	SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
+    // GL 3.3 Core
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, 0);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);
 #endif
 
 	SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);

Backends/RmlUi_Renderer_GL3.cpp

@@ -48,6 +48,9 @@
 #if defined RMLUI_PLATFORM_EMSCRIPTEN
 	#define RMLUI_SHADER_HEADER_VERSION "#version 300 es\nprecision highp float;\n"
 	#include <GLES3/gl3.h>
+#elif defined __ANDROID__
+	#define RMLUI_SHADER_HEADER_VERSION "#version 320 es\nprecision highp float;\n"
+	#include <GLES3/gl32.h>
 #elif defined RMLUI_GL3_CUSTOM_LOADER
 	#define RMLUI_SHADER_HEADER_VERSION "#version 330\n"
 	#include RMLUI_GL3_CUSTOM_LOADER
@@ -618,7 +621,7 @@ static bool CreateProgram(GLuint& out_program, Uniforms& inout_uniform_map, Prog
 static bool CreateFramebuffer(FramebufferData& out_fb, int width, int height, int samples, FramebufferAttachment attachment,
 	GLuint shared_depth_stencil_buffer)
 {
-#ifdef RMLUI_PLATFORM_EMSCRIPTEN
+#if defined(RMLUI_PLATFORM_EMSCRIPTEN) || defined(__ANDROID__)
 	constexpr GLint wrap_mode = GL_CLAMP_TO_EDGE;
 #else
 	constexpr GLint wrap_mode = GL_CLAMP_TO_BORDER; // GL_REPEAT GL_MIRRORED_REPEAT GL_CLAMP_TO_EDGE
@@ -651,7 +654,7 @@ static bool CreateFramebuffer(FramebufferData& out_fb, int width, int height, in
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, min_mag_filter);
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, wrap_mode);
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, wrap_mode);
-#ifndef RMLUI_PLATFORM_EMSCRIPTEN
+#if !defined(RMLUI_PLATFORM_EMSCRIPTEN) && !defined(__ANDROID__)
 		glTexParameterfv(GL_TEXTURE_2D, GL_TEXTURE_BORDER_COLOR, &border_color[0]);
 #endif
 
@@ -894,7 +897,7 @@ void RenderInterface_GL3::BeginFrame()
 	glBlendEquation(GL_FUNC_ADD);
 	glBlendFunc(GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
 
-#ifndef RMLUI_PLATFORM_EMSCRIPTEN
+#if !defined(RMLUI_PLATFORM_EMSCRIPTEN) && !defined(__ANDROID__)
 	// We do blending in nonlinear sRGB space because that is the common practice and gives results that we are used to.
 	glDisable(GL_FRAMEBUFFER_SRGB);
 #endif
@@ -2165,9 +2168,12 @@ void RenderInterface_GL3::ResetProgram()
 
 bool RmlGL3::Initialize(Rml::String* out_message)
 {
-#if defined RMLUI_PLATFORM_EMSCRIPTEN
-	if (out_message)
-		*out_message = "Started Emscripten WebGL renderer.";
+#if defined(RMLUI_PLATFORM_EMSCRIPTEN)
+    if (out_message)
+        *out_message = "Started Emscripten WebGL renderer.";
+#elif defined(__ANDROID__)
+    if (out_message)
+        *out_message = "Started OpenGL ES 3 renderer.";
 #elif !defined RMLUI_GL3_CUSTOM_LOADER
 	const int gl_version = gladLoaderLoadGL();
 	if (gl_version == 0)
@@ -2186,7 +2192,7 @@ bool RmlGL3::Initialize(Rml::String* out_message)
 
 void RmlGL3::Shutdown()
 {
-#if !defined RMLUI_PLATFORM_EMSCRIPTEN && !defined RMLUI_GL3_CUSTOM_LOADER
+#if !defined(RMLUI_PLATFORM_EMSCRIPTEN) && !defined(__ANDROID__) && !defined(RMLUI_GL3_CUSTOM_LOADER)
 	gladLoaderUnloadGL();
 #endif
 }