[core] Added save/restore capabilities to GL config

include/mbgl/map/mode.hpp

@@ -10,6 +10,10 @@ enum class MapMode : uint8_t {
     Still, // a once-off still image
 };
 
+// We can avoid redundant GL calls when it is known that the GL context is not
+// being shared. In a shared GL context case, we need to make sure that the
+// correct GL configurations are in use - they might have changed between render
+// calls.
 enum class GLContextMode : uint8_t {
     Unique,
     Shared,

src/mbgl/renderer/gl_config.hpp

@@ -25,6 +25,14 @@ public:
         T::Set(current);
     }
 
+    inline void save() {
+        current = T::Get();
+    }
+
+    inline void restore() {
+        T::Set(current);
+    }
+
 private:
     typename T::Type current = T::Default;
 };
@@ -35,14 +43,24 @@ struct ClearDepth {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glClearDepth(value));
     }
+    inline static Type Get() {
+        Type clearDepth;
+        MBGL_CHECK_ERROR(glGetFloatv(GL_DEPTH_CLEAR_VALUE, &clearDepth));
+        return clearDepth;
+    }
 };
 
 struct ClearColor {
-    struct Type { float r, g, b, a; };
+    struct Type { GLfloat r, g, b, a; };
     static const Type Default;
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glClearColor(value.r, value.g, value.b, value.a));
     }
+    inline static Type Get() {
+        GLfloat floats[4];
+        MBGL_CHECK_ERROR(glGetFloatv(GL_COLOR_CLEAR_VALUE, floats));
+        return { floats[0], floats[1], floats[2], floats[3] };
+    }
 };
 
 inline bool operator!=(const ClearColor::Type& a, const ClearColor::Type& b) {
@@ -55,6 +73,11 @@ struct ClearStencil {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glClearStencil(value));
     }
+    inline static Type Get() {
+        Type clearStencil;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_CLEAR_VALUE, &clearStencil));
+        return clearStencil;
+    }
 };
 
 struct StencilMask {
@@ -63,6 +86,11 @@ struct StencilMask {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glStencilMask(value));
     }
+    inline static Type Get() {
+        GLint stencilMask;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_WRITEMASK, &stencilMask));
+        return stencilMask;
+    }
 };
 
 struct DepthMask {
@@ -71,6 +99,11 @@ struct DepthMask {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glDepthMask(value));
     }
+    inline static Type Get() {
+        Type depthMask;
+        MBGL_CHECK_ERROR(glGetBooleanv(GL_DEPTH_WRITEMASK, &depthMask));
+        return depthMask;
+    }
 };
 
 struct ColorMask {
@@ -79,6 +112,11 @@ struct ColorMask {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glColorMask(value.r, value.g, value.b, value.a));
     }
+    inline static Type Get() {
+        GLfloat floats[4];
+        MBGL_CHECK_ERROR(glGetFloatv(GL_COLOR_WRITEMASK, floats));
+        return { floats[0], floats[1], floats[2], floats[3] };
+    }
 };
 
 inline bool operator!=(const ColorMask::Type& a, const ColorMask::Type& b) {
@@ -91,6 +129,13 @@ struct StencilFunc {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glStencilFunc(value.func, value.ref, value.mask));
     }
+    inline static Type Get() {
+        GLint func, ref, mask;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_FUNC, &func));
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_REF, &ref));
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_VALUE_MASK, &mask));
+        return { static_cast<GLenum>(func), ref, static_cast<GLuint>(mask) };
+    }
 };
 
 inline bool operator!=(const StencilFunc::Type& a, const StencilFunc::Type& b) {
@@ -103,6 +148,11 @@ struct StencilTest {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(value ? glEnable(GL_STENCIL_TEST) : glDisable(GL_STENCIL_TEST));
     }
+    inline static Type Get() {
+        Type stencilTest;
+        MBGL_CHECK_ERROR(stencilTest = glIsEnabled(GL_STENCIL_TEST));
+        return stencilTest;
+    }
 };
 
 struct StencilOp {
@@ -111,6 +161,13 @@ struct StencilOp {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glStencilOp(value.sfail, value.dpfail, value.dppass));
     }
+    inline static Type Get() {
+        GLint sfail, dpfail, dppass;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_FAIL, &sfail));
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_PASS_DEPTH_FAIL, &dpfail));
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_STENCIL_PASS_DEPTH_PASS, &dppass));
+        return { static_cast<GLenum>(sfail), static_cast<GLenum>(dpfail), static_cast<GLuint>(dppass) };
+    }
 };
 
 struct DepthRange {
@@ -119,6 +176,11 @@ struct DepthRange {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glDepthRange(value.near, value.far));
     }
+    inline static Type Get() {
+        GLfloat floats[2];
+        MBGL_CHECK_ERROR(glGetFloatv(GL_DEPTH_RANGE, floats));
+        return { floats[0], floats[1] };
+    }
 };
 
 inline bool operator!=(const DepthRange::Type& a, const DepthRange::Type& b) {
@@ -131,6 +193,11 @@ struct DepthTest {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(value ? glEnable(GL_DEPTH_TEST) : glDisable(GL_DEPTH_TEST));
     }
+    inline static Type Get() {
+        Type depthTest;
+        MBGL_CHECK_ERROR(depthTest = glIsEnabled(GL_DEPTH_TEST));
+        return depthTest;
+    }
 };
 
 struct DepthFunc {
@@ -139,6 +206,11 @@ struct DepthFunc {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glDepthFunc(value));
     }
+    inline static Type Get() {
+        GLint depthFunc;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_DEPTH_FUNC, &depthFunc));
+        return depthFunc;
+    }
 };
 
 struct Blend {
@@ -147,6 +219,11 @@ struct Blend {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(value ? glEnable(GL_BLEND) : glDisable(GL_BLEND));
     }
+    inline static Type Get() {
+        Type blend;
+        MBGL_CHECK_ERROR(blend = glIsEnabled(GL_BLEND));
+        return blend;
+    }
 };
 
 struct BlendFunc {
@@ -155,6 +232,12 @@ struct BlendFunc {
     inline static void Set(const Type& value) {
         MBGL_CHECK_ERROR(glBlendFunc(value.sfactor, value.dfactor));
     }
+    inline static Type Get() {
+        GLint sfactor, dfactor;
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_BLEND_SRC_ALPHA, &sfactor));
+        MBGL_CHECK_ERROR(glGetIntegerv(GL_BLEND_DST_ALPHA, &dfactor));
+        return { static_cast<GLenum>(sfactor), static_cast<GLenum>(dfactor) };
+    }
 };
 
 class Config {
@@ -176,6 +259,40 @@ public:
         clearStencil.reset();
     }
 
+    void restore() {
+        stencilFunc.restore();
+        stencilMask.restore();
+        stencilTest.restore();
+        stencilOp.restore();
+        depthRange.restore();
+        depthMask.restore();
+        depthTest.restore();
+        depthFunc.restore();
+        blend.restore();
+        blendFunc.restore();
+        colorMask.restore();
+        clearDepth.restore();
+        clearColor.restore();
+        clearStencil.restore();
+    }
+
+    void save() {
+        stencilFunc.save();
+        stencilMask.save();
+        stencilTest.save();
+        stencilOp.save();
+        depthRange.save();
+        depthMask.save();
+        depthTest.save();
+        depthFunc.save();
+        blend.save();
+        blendFunc.save();
+        colorMask.save();
+        clearDepth.save();
+        clearColor.save();
+        clearStencil.save();
+    }
+
     Value<StencilFunc> stencilFunc;
     Value<StencilMask> stencilMask;
     Value<StencilTest> stencilTest;

src/mbgl/renderer/painter.cpp

@@ -147,6 +147,10 @@ void Painter::render(const Style& style, TransformState state_, const FrameData&
     state = state_;
     frame = frame_;
 
+    if (data.contextMode == GLContextMode::Shared) {
+        config.restore();
+    }
+
     glyphAtlas = style.glyphAtlas.get();
     spriteAtlas = style.spriteAtlas.get();
     lineAtlas = style.lineAtlas.get();
@@ -244,6 +248,10 @@ void Painter::render(const Style& style, TransformState state_, const FrameData&
         MBGL_CHECK_ERROR(glBindTexture(GL_TEXTURE_2D, 0));
         MBGL_CHECK_ERROR(VertexArrayObject::Unbind());
     }
+
+    if (data.contextMode == GLContextMode::Shared) {
+        config.save();
+    }
 }
 
 template <class Iterator>