surfaceflinger: use Vulkan coordinate system

In Vulkan coordinate system, (0, 0) always maps to memory address 0.
In GL coordinate system, (0, 0) maps to the bottom-left corner.  The
two agree when doing offscreen rendering.  But when rendering to a
window, GL maps (0, 0) to memory address (winHeight-1)*rowStride,
because that is where the bottom-left pixel is.

Let's pick the simpler one for RenderEngine in preparation for
multiple backends.  As a result, we don't need yswap when rendering
to offscreen buffers (it is hidden behind the RenderEngine API).  It
also makes no sense to flip Y coordinate for both vertex postions
and the viewing volume.

Test: chrome, youtube, camera, screen rotation, screenshots, recents
Change-Id: I6d6317bac3de6f208700a67e518011362c600ced
diff --git a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.cpp b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.cpp
index e0f1850..42d4887 100644
--- a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.cpp
+++ b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.cpp
@@ -160,21 +160,15 @@
 }
 
 void GLES20RenderEngine::setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop,
-                                                  size_t hwh, bool yswap,
                                                   ui::Transform::orientation_flags rotation) {
     int32_t l = sourceCrop.left;
     int32_t r = sourceCrop.right;
-
-    // In GL, (0, 0) is the bottom-left corner, so flip y coordinates
-    int32_t t = hwh - sourceCrop.top;
-    int32_t b = hwh - sourceCrop.bottom;
-
-    mat4 m;
-    if (yswap) {
-        m = mat4::ortho(l, r, t, b, 0, 1);
-    } else {
-        m = mat4::ortho(l, r, b, t, 0, 1);
+    int32_t b = sourceCrop.bottom;
+    int32_t t = sourceCrop.top;
+    if (mRenderToFbo) {
+        std::swap(t, b);
     }
+    mat4 m = mat4::ortho(l, r, b, t, 0, 1);
 
     // Apply custom rotation to the projection.
     float rot90InRadians = 2.0f * static_cast<float>(M_PI) / 4.0f;
@@ -284,9 +278,13 @@
     *status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
     *texName = tname;
     *fbName = name;
+
+    mRenderToFbo = true;
 }
 
 void GLES20RenderEngine::unbindFramebuffer(uint32_t texName, uint32_t fbName) {
+    mRenderToFbo = false;
+
     glBindFramebuffer(GL_FRAMEBUFFER, 0);
     glDeleteFramebuffers(1, &fbName);
     glDeleteTextures(1, &texName);
diff --git a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
index c830184..e6a7a00 100644
--- a/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/gl/GLES20RenderEngine.h
@@ -62,8 +62,8 @@
 
 protected:
     virtual void dump(String8& result);
-    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop, size_t hwh,
-                                          bool yswap, ui::Transform::orientation_flags rotation);
+    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop,
+                                          ui::Transform::orientation_flags rotation);
     virtual void setupLayerBlending(bool premultipliedAlpha, bool opaque, bool disableTexture,
                                     const half4& color) override;
 
@@ -108,6 +108,8 @@
     // with PQ or HLG transfer function.
     bool isHdrDataSpace(const ui::Dataspace dataSpace) const;
     bool needsXYZTransformMatrix() const;
+
+    bool mRenderToFbo = false;
 };
 
 }  // namespace gl
diff --git a/services/surfaceflinger/RenderEngine/include/renderengine/RenderEngine.h b/services/surfaceflinger/RenderEngine/include/renderengine/RenderEngine.h
index c532adc..a363cd4 100644
--- a/services/surfaceflinger/RenderEngine/include/renderengine/RenderEngine.h
+++ b/services/surfaceflinger/RenderEngine/include/renderengine/RenderEngine.h
@@ -96,14 +96,15 @@
     virtual void deleteTextures(size_t count, uint32_t const* names) = 0;
     virtual void bindExternalTextureImage(uint32_t texName, const renderengine::Image& image) = 0;
     virtual void readPixels(size_t l, size_t b, size_t w, size_t h, uint32_t* pixels) = 0;
+    // When binding a native buffer, it must be done before setViewportAndProjection
     virtual void bindNativeBufferAsFrameBuffer(ANativeWindowBuffer* buffer,
                                                BindNativeBufferAsFramebuffer* bindHelper) = 0;
     virtual void unbindNativeBufferAsFrameBuffer(BindNativeBufferAsFramebuffer* bindHelper) = 0;
 
     // set-up
     virtual void checkErrors() const;
-    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop, size_t hwh,
-                                          bool yswap, ui::Transform::orientation_flags rotation) = 0;
+    virtual void setViewportAndProjection(size_t vpw, size_t vph, Rect sourceCrop,
+                                          ui::Transform::orientation_flags rotation) = 0;
     virtual void setupLayerBlending(bool premultipliedAlpha, bool opaque, bool disableTexture,
                                     const half4& color) = 0;
     virtual void setupLayerTexturing(const Texture& texture) = 0;