Implement lightning effect using shaders

data/shaders/lightning.frag

@@ -0,0 +1,7 @@
+uniform vec3 intensity;
+out vec4 FragColor;
+
+void main()
+{
+	FragColor = vec4(intensity, 1.0f);
+}

src/graphics/post_processing.cpp

@@ -818,6 +818,24 @@ public:
     }   // render
 };   // SunLightShader
 
+// ============================================================================
+class LightningShader : public TextureShader<LightningShader, 1, 
+                                             core::vector3df>
+{
+public:
+    LightningShader()
+    {
+        loadProgram(OBJECT, GL_VERTEX_SHADER, "screenquad.vert",
+                            GL_FRAGMENT_SHADER, "lightning.frag");
+        assignUniforms("intensity");
+    }   // LightningShader
+    // ------------------------------------------------------------------------
+    void render(core::vector3df intensity)
+    {
+        drawFullScreenEffect(intensity);
+    }   // render
+};   // LightningShader
+
 // ============================================================================
 
 PostProcessing::PostProcessing(IVideoDriver* video_driver)
@@ -1408,6 +1426,18 @@ void PostProcessing::applyMLAA()
     glDisable(GL_STENCIL_TEST);
 }   // applyMLAA
 
+// ----------------------------------------------------------------------------
+void PostProcessing::renderLightning(core::vector3df intensity)
+{
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_ONE, GL_ONE);
+    glBlendEquation(GL_FUNC_ADD);
+       
+    LightningShader::getInstance()->render(intensity);
+    
+    glDisable(GL_BLEND);
+}
+
 // ----------------------------------------------------------------------------
 /** Render the post-processed scene */
 FrameBuffer *PostProcessing::render(scene::ICameraSceneNode * const camnode,

src/graphics/post_processing.hpp

@@ -105,6 +105,7 @@ public:
     void renderMotionBlur(unsigned cam, const FrameBuffer &in_fbo,
                           FrameBuffer &out_fbo);
     void renderGlow(unsigned tex);
+    void renderLightning(core::vector3df intensity);
 
     /** Render the post-processed scene */
     FrameBuffer *render(scene::ICameraSceneNode * const camnode, bool isRace);

src/states_screens/race_gui_base.cpp

@@ -22,11 +22,13 @@
 
 #include "audio/music_manager.hpp"
 #include "config/user_config.hpp"
-#include "graphics/camera.hpp"
 #include "graphics/2dutils.hpp"
+#include "graphics/camera.hpp"
+#include "graphics/central_settings.hpp"
 #include "graphics/irr_driver.hpp"
 #include "graphics/material.hpp"
 #include "graphics/material_manager.hpp"
+#include "graphics/post_processing.hpp"
 #include "graphics/referee.hpp"
 #include "guiengine/scalable_font.hpp"
 #include "io/file_manager.hpp"
@@ -410,6 +412,17 @@ void RaceGUIBase::preRenderCallback(const Camera *camera)
 // ----------------------------------------------------------------------------
 void RaceGUIBase::renderPlayerView(const Camera *camera, float dt)
 {
+    if (CVS->isGLSL())
+    {
+        if (m_lightning > 0.0f)
+        {
+            core::vector3df intensity = {0.7f * m_lightning, 
+                                         0.7f * m_lightning, 
+                                         0.7f * std::min(1.0f, m_lightning * 1.5f)};
+            irr_driver->getPostProcessing()->renderLightning(intensity);
+        }
+    }
+    
 #if 0
     const core::recti &viewport = camera->getViewport();