From b1a2513b61761d09b3ae08904c03d28caedd09fe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Konstantin=20K=C3=A4fer?= <mail@kkaefer.com>
Date: Wed, 3 Apr 2019 14:18:54 +0200
Subject: [core] test OffscreenTexture renderability before using them

---
 src/mbgl/gfx/offscreen_texture.hpp                | 2 ++
 src/mbgl/gl/offscreen_texture.cpp                 | 9 +++++++++
 src/mbgl/gl/offscreen_texture.hpp                 | 2 ++
 src/mbgl/renderer/layers/render_heatmap_layer.cpp | 5 +----
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/src/mbgl/gfx/offscreen_texture.hpp b/src/mbgl/gfx/offscreen_texture.hpp
index 1eaf4557c6..5690ff7625 100644
--- a/src/mbgl/gfx/offscreen_texture.hpp
+++ b/src/mbgl/gfx/offscreen_texture.hpp
@@ -17,6 +17,8 @@ protected:
 public:
     virtual ~OffscreenTexture() = default;
 
+    virtual bool isRenderable() = 0;
+
     virtual PremultipliedImage readStillImage() = 0;
     virtual gfx::Texture& getTexture() = 0;
 };
diff --git a/src/mbgl/gl/offscreen_texture.cpp b/src/mbgl/gl/offscreen_texture.cpp
index 96d8b7e4c4..0b06fedf46 100644
--- a/src/mbgl/gl/offscreen_texture.cpp
+++ b/src/mbgl/gl/offscreen_texture.cpp
@@ -75,6 +75,15 @@ OffscreenTexture::OffscreenTexture(
           size, std::make_unique<OffscreenTextureResource>(context, size_, renderbuffer, type)) {
 }
 
+bool OffscreenTexture::isRenderable() {
+    try {
+        getResource<OffscreenTextureResource>().bind();
+        return true;
+    } catch (const std::runtime_error& ex) {
+        return false;
+    }
+}
+
 PremultipliedImage OffscreenTexture::readStillImage() {
     return getResource<OffscreenTextureResource>().readStillImage();
 }
diff --git a/src/mbgl/gl/offscreen_texture.hpp b/src/mbgl/gl/offscreen_texture.hpp
index 5b211df505..07da4f57e2 100644
--- a/src/mbgl/gl/offscreen_texture.hpp
+++ b/src/mbgl/gl/offscreen_texture.hpp
@@ -18,6 +18,8 @@ public:
                      gfx::Renderbuffer<gfx::RenderbufferPixelType::Depth>&,
                      gfx::TextureChannelDataType type = gfx::TextureChannelDataType::UnsignedByte);
 
+    bool isRenderable() override;
+
     PremultipliedImage readStillImage() override;
     gfx::Texture& getTexture() override;
 };
diff --git a/src/mbgl/renderer/layers/render_heatmap_layer.cpp b/src/mbgl/renderer/layers/render_heatmap_layer.cpp
index 15345ffe9e..f8a159f3da 100644
--- a/src/mbgl/renderer/layers/render_heatmap_layer.cpp
+++ b/src/mbgl/renderer/layers/render_heatmap_layer.cpp
@@ -62,10 +62,7 @@ void RenderHeatmapLayer::render(PaintParameters& parameters, RenderSource*) {
             if (parameters.context.supportsHalfFloatTextures) {
                 renderTexture = parameters.context.createOffscreenTexture(size, gfx::TextureChannelDataType::HalfFloat);
 
-                // TODO: try binding in the offscreen texture constructor
-                try {
-                    renderTexture->getResource<gl::RenderableResource>().bind();
-                } catch (const std::runtime_error& ex) {
+                if (!renderTexture->isRenderable()) {
                     // can't render to a half-float texture; falling back to unsigned byte one
                     renderTexture.reset();
                     parameters.context.supportsHalfFloatTextures = false;
-- 
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