From 36b249d4dc77ef6cc81c0fd3991e3ec80f9c1bcc Mon Sep 17 00:00:00 2001
From: Brad Davis <bdavis@saintandreas.org>
Date: Thu, 25 Jul 2019 18:24:53 -0700
Subject: [PATCH] BUGZ-964: fix for incorrect color curve when rendering 3D
 into QML

---
 interface/src/ui/ResourceImageItem.cpp | 70 +++++++++++++++++++++++---
 interface/src/ui/ResourceImageItem.h   | 11 ++--
 2 files changed, 70 insertions(+), 11 deletions(-)

diff --git a/interface/src/ui/ResourceImageItem.cpp b/interface/src/ui/ResourceImageItem.cpp
index f14f4ca78e..46ffffe62d 100644
--- a/interface/src/ui/ResourceImageItem.cpp
+++ b/interface/src/ui/ResourceImageItem.cpp
@@ -11,11 +11,52 @@
 #include "ResourceImageItem.h"
 
 #include <gl/Config.h>
-
+#include <gl/GLHelpers.h>
 #include <QOpenGLFramebufferObjectFormat>
+#include <QOpenGLShaderProgram>
 
 #include <plugins/DisplayPlugin.h>
 
+
+static const char* VERTEX_SHADER = R"SHADER(
+#version 450 core
+
+out vec2 vTexCoord;
+
+void main(void) {
+    const float depth = 0.0;
+    const vec4 UNIT_QUAD[4] = vec4[4](
+        vec4(-1.0, -1.0, depth, 1.0),
+        vec4(1.0, -1.0, depth, 1.0),
+        vec4(-1.0, 1.0, depth, 1.0),
+        vec4(1.0, 1.0, depth, 1.0)
+    );
+    vec4 pos = UNIT_QUAD[gl_VertexID];
+
+    gl_Position = pos;
+    vTexCoord = (pos.xy + 1.0) * 0.5;
+}
+)SHADER";
+
+static const char* FRAGMENT_SHADER = R"SHADER(
+#version 450 core
+
+uniform sampler2D sampler;
+
+in vec2 vTexCoord;
+
+out vec4 FragColor;
+
+vec3 color_LinearTosRGB(vec3 lrgb) {
+    return mix(vec3(1.055) * pow(vec3(lrgb), vec3(0.41666)) - vec3(0.055), vec3(lrgb) * vec3(12.92), vec3(lessThan(lrgb, vec3(0.0031308))));
+}
+
+void main() {
+    FragColor = vec4(color_LinearTosRGB(texture(sampler, vTexCoord).rgb), 1.0);
+}
+)SHADER";
+
+
 ResourceImageItem::ResourceImageItem() : QQuickFramebufferObject() {
     auto textureCache = DependencyManager::get<TextureCache>();
     connect(textureCache.data(), SIGNAL(spectatorCameraFramebufferReset()), this, SLOT(update()));
@@ -95,16 +136,29 @@ void ResourceImageItemRenderer::render() {
     }
     if (_ready) {
         _fboMutex.lock();
-        _copyFbo->bind();
-        QOpenGLFramebufferObject::blitFramebuffer(framebufferObject(), _copyFbo, GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT, GL_NEAREST);
 
-        // this clears the copyFbo texture
-        // so next frame starts fresh - helps
-        // when aspect ratio changes
-        _copyFbo->takeTexture();
+
+        if (!_shader) {
+            _shader = new QOpenGLShaderProgram();
+            _shader->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, VERTEX_SHADER);
+            _shader->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment, FRAGMENT_SHADER);
+            _shader->link();
+            glGenVertexArrays(1, &_vao);
+        }
+        framebufferObject()->bind();
+        _shader->bind();
+
+        auto sourceTextureId = _copyFbo->takeTexture();
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, sourceTextureId);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+        glBindVertexArray(_vao);
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+        glDeleteTextures(1, &sourceTextureId);
+
         _copyFbo->bind();
         _copyFbo->release();
-
         _fboMutex.unlock();
     }
     glFlush();
diff --git a/interface/src/ui/ResourceImageItem.h b/interface/src/ui/ResourceImageItem.h
index d154588094..1a679ba2ee 100644
--- a/interface/src/ui/ResourceImageItem.h
+++ b/interface/src/ui/ResourceImageItem.h
@@ -22,6 +22,9 @@
 
 #include <TextureCache.h>
 
+class QOpenGLFramebufferObject;
+class QOpenGLShaderProgram;
+
 class ResourceImageItemRenderer : public QObject, public QQuickFramebufferObject::Renderer {
     Q_OBJECT
 public:
@@ -30,14 +33,16 @@ public:
     void synchronize(QQuickFramebufferObject* item) override;
     void render() override;
 private:
-    bool _ready;
+    bool _ready{ false };
     QString _url;
-    bool _visible;
+    bool _visible{ false };
 
     NetworkTexturePointer _networkTexture;
-    QQuickWindow* _window;
+    QQuickWindow* _window{ nullptr };
     QMutex _fboMutex;
+    uint32_t _vao{ 0 };
     QOpenGLFramebufferObject* _copyFbo { nullptr };
+    QOpenGLShaderProgram* _shader{ nullptr };
     GLsync _fenceSync { 0 };
     QTimer _updateTimer;
 public slots: