Renderer|FX|libgui: Working on accessing the depth buffer from a shader

doomsday/client/data/renderer.pack/shaders/lensflares.fsh

@@ -5,16 +5,9 @@ varying highp vec2 vUV;
 void main(void) {
     highp vec4 tex = texture2D(uTex, vUV);
     gl_FragColor = tex * vColor;
-
-    /*
-    highp vec4 original = texture2D(uTex, vUV);
-    highp float intens = 
-        (0.2125 * original.r) + 
-        (0.7154 * original.g) + 
-        (0.0721 * original.b);
-    gl_FragColor = vec4(vec3(intens), 1.0);
-    if(uFadeInOut < 1.0) {
-        gl_FragColor = mix(original, gl_FragColor, uFadeInOut);
+
+    // Discard fragments without alpha.
+    if(gl_FragColor.a <= 0.0) { 
+        discard; 
     }
-    */
 }

doomsday/client/data/renderer.pack/shaders/lensflares.vsh

@@ -1,10 +1,13 @@
 uniform highp mat4 uMvpMatrix;
 uniform highp vec2 uViewUnit;
+uniform sampler2D uDepthBuf;
+
 attribute highp vec4 aVertex;
 attribute highp vec4 aColor;
 attribute highp vec2 aUV;
 attribute highp vec2 aUV2;
 attribute highp vec2 aUV3;
+
 varying highp vec4 vColor;
 varying highp vec2 vUV;
 
@@ -14,9 +17,26 @@ void main(void) {
     // Position on the axis that passes through the center of the view.
     highp float axisPos = aUV3.s;
     gl_Position.xy *= axisPos;
+
+    // Is this occluded in the depth buffer?
+    highp vec2 depthUv = gl_Position.xy / gl_Position.w / 2.0 + vec2(0.5, 0.5);
+    float depth = texture2D(uDepthBuf, depthUv).r;
+/*    if(depth < (gl_Position.z/gl_Position.w + 1.0)/2.0) {
+        // Occluded!
+        vUV = aUV;
+        vColor = vec4(0.0, 0.0, 0.0, 0.0);
+        return;        
+    }    */
 
     gl_Position.xy += aUV2 * uViewUnit * vec2(gl_Position.w);
 
     vUV = aUV;
     vColor = aColor;
+
+    if(depth < (gl_Position.z/gl_Position.w + 1)/2) {
+        // Occluded!
+        vColor = vec4(1.0, 0.0, 0.0, 1.0);
+        return;        
+    }    
+
 }

doomsday/client/src/render/fx/lensflares.cpp

@@ -228,6 +228,7 @@ DENG2_PIMPL(LensFlares)
     GLUniform uMvpMatrix;
     GLUniform uViewUnit;
     GLUniform uAtlas;
+    GLUniform uDepthBuf;
 
     Instance(Public *i)
         : Base(i)
@@ -236,6 +237,7 @@ DENG2_PIMPL(LensFlares)
         , uMvpMatrix("uMvpMatrix", GLUniform::Mat4)
         , uViewUnit ("uViewUnit",  GLUniform::Vec2)
         , uAtlas    ("uTex",       GLUniform::Sampler2D)
+        , uDepthBuf ("uDepthBuf",  GLUniform::Sampler2D)
     {}
 
     ~Instance()
@@ -254,9 +256,10 @@ DENG2_PIMPL(LensFlares)
         drawable.addBuffer(buffer);
         self.shaders().build(drawable.program(), "fx.lensflares")
                 << uMvpMatrix << uViewUnit
-                << uAtlas;
+                << uAtlas << uDepthBuf;
 
         uAtlas = res->atlas;
+        //uDepthBuf = ClientWindow::main().canvas().depthTexture();
     }
 
     void glDeinit()

doomsday/libgui/include/de/gui/canvas.h

@@ -160,6 +160,13 @@ class LIBGUI_PUBLIC Canvas : public QGLWidget, public KeyEventSource, public Mou
      */
     GLTarget &renderTarget() const;
 
+    /**
+     * Returns the GL texture containing the depth buffer.
+     *
+     * @return GL depth target.
+     */
+    GLTexture &depthTexture() const;
+
 protected:
     void initializeGL();
     void resizeGL(int w, int h);

doomsday/libgui/include/de/gui/gltarget.h

@@ -54,6 +54,7 @@ class LIBGUI_PUBLIC GLTarget : public Asset
 
         ColorDepth        = Color | Depth,
         ColorDepthStencil = Color | Depth | Stencil,
+        ColorStencil      = Color | Stencil,
         DepthStencil      = Depth | Stencil,
 
         NoAttachments = 0,
@@ -101,6 +102,17 @@ class LIBGUI_PUBLIC GLTarget : public Asset
 
     Flags flags() const;
 
+    /**
+     * Changes the configuration of the render target. Any previously allocated
+     * renderbuffers are released.
+     *
+     * @param attachment  Where to attach @a texture.
+     * @param texture     Texture to render on.
+     * @param otherAttachments  Other supporting attachments (renderbuffers).
+     */
+    void configure(Flags const &attachment, GLTexture &texture,
+                   Flags const &otherAttachments = NoAttachments);
+
     /**
      * Activates this render target as the one where GL drawing is being done.
      */

doomsday/libgui/include/de/gui/gltexture.h

@@ -150,6 +150,10 @@ class LIBGUI_PUBLIC GLTexture : public Asset
      */
     void setUndefinedImage(gl::CubeFace face, Size const &size, Image::Format format, int level = 0);
 
+    void setUndefinedContent(Size const &size, Image::GLFormat const &glFormat, int level = 0);
+
+    void setUndefinedContent(gl::CubeFace face, Size const &size, Image::GLFormat const &glFormat, int level = 0);
+
     /**
      * Sets the image content of the texture at a particular level. The format
      * of the image determines which GL format is chosen for the texture.

doomsday/libgui/src/canvas.cpp

@@ -20,6 +20,7 @@
 #include "de/Canvas"
 #include "de/CanvasWindow"
 #include "de/GLState"
+#include "de/GLTexture"
 #include "de/gui/opengl.h"
 
 #include <de/App>
@@ -44,6 +45,8 @@ static const int MOUSE_WHEEL_CONTINUOUS_THRESHOLD_MS = 100;
 DENG2_PIMPL(Canvas)
 {
     GLTarget target;
+    GLTexture depthTexture; ///< Texture where framebuffer depth values are available.
+
     CanvasWindow *parent;
     bool readyNotified;
     Size currentSize;
@@ -62,7 +65,7 @@ DENG2_PIMPL(Canvas)
           readyNotified(false),
           //mouseDisabled(false),
           mouseGrabbed(false)
-    {
+    {        
         wheelDir[0] = wheelDir[1] = 0;
 #ifdef WIN32
         altIsDown = false;
@@ -268,6 +271,11 @@ GLTarget &Canvas::renderTarget() const
     return d->target;
 }
 
+GLTexture &Canvas::depthTexture() const
+{
+    return d->depthTexture;
+}
+
 void Canvas::initializeGL()
 {
     LOG_AS("Canvas");
@@ -320,6 +328,10 @@ void Canvas::notifyReady()
 
     d->readyNotified = true;
 
+    // Set up a rendering target with depth texture.
+    //d->depthTexture.setUndefinedContent(size(), Image::GLFormat(GL_DEPTH_COMPONENT, GL_UNSIGNED_SHORT, 2));
+    //d->target.configure(GLTarget::Depth, d->depthTexture, GLTarget::Color);
+
     LOG_DEBUG("Notifying GL ready");
 
     DENG2_FOR_AUDIENCE(GLReady, i) i->canvasGLReady(*this);

doomsday/libgui/src/gltarget.cpp

@@ -247,6 +247,19 @@ GLTarget::GLTarget(Vector2ui const &size, Flags const &flags)
     d->alloc();
 }
 
+void GLTarget::configure(Flags const &attachment, GLTexture &texture, Flags const &otherAttachments)
+{
+    d->release();
+
+    // Set new configuration.
+    d->texture = &texture;
+    d->textureAttachment = attachment;
+    d->flags = attachment | otherAttachments;
+    d->size = texture.size();
+
+    d->alloc();
+}
+
 void GLTarget::glBind() const
 {
     if(!isReady()) return;

doomsday/libgui/src/gltexture.cpp

@@ -309,6 +309,34 @@ void GLTexture::setUndefinedImage(CubeFace face, GLTexture::Size const &size,
     setState(Ready);
 }
 
+void GLTexture::setUndefinedContent(Size const &size, Image::GLFormat const &glFormat, int level)
+{
+    d->texTarget = GL_TEXTURE_2D;
+    d->size = size;
+    d->format = Image::Unknown;
+
+    d->alloc();
+    d->glBind();
+    d->glImage(level, size, glFormat, NULL);
+    d->glUnbind();
+
+    setState(Ready);
+}
+
+void GLTexture::setUndefinedContent(CubeFace face, Size const &size, Image::GLFormat const &glFormat, int level)
+{
+    d->texTarget = GL_TEXTURE_CUBE_MAP;
+    d->size = size;
+    d->format = Image::Unknown;
+
+    d->alloc();
+    d->glBind();
+    d->glImage(level, size, glFormat, NULL, face);
+    d->glUnbind();
+
+    setState(Ready);
+}
+
 void GLTexture::setImage(Image const &image, int level)
 {
     d->texTarget = GL_TEXTURE_2D;