Add transition/blending progress to render context

Author: kblaschke

src/libprojectM/ProjectM.cpp

@@ -456,6 +456,15 @@ auto ProjectM::GetRenderContext() -> Renderer::RenderContext
     ctx.textureManager = m_textureManager.get();
     ctx.shaderCache = m_shaderCache.get();
 
+    if (m_transition)
+    {
+        ctx.blendProgress = m_transition->Progress(ctx.time);
+    }
+    else
+    {
+        ctx.blendProgress = 0.0;
+    }
+
     return ctx;
 }
 

src/libprojectM/Renderer/PresetTransition.cpp

@@ -2,6 +2,7 @@
 
 #include "TextureManager.hpp"
 
+#include <algorithm>
 #include <array>
 #include <cmath>
 #include <cstddef>
@@ -40,6 +41,11 @@ auto PresetTransition::IsDone(double currentFrameTime) const -> bool
     return m_durationSeconds <= 0.0 || secondsSinceStart >= m_durationSeconds;
 }
 
+auto PresetTransition::Progress(double currentFrameTime) const -> double
+{
+    return std::min(std::max((currentFrameTime - m_transitionStartTime) / m_durationSeconds, 0.0), 1.0);
+}
+
 void PresetTransition::Draw(const Preset& oldPreset,
                             const Preset& newPreset,
                             const RenderContext& context,

src/libprojectM/Renderer/PresetTransition.hpp

@@ -40,6 +40,13 @@ class PresetTransition : public RenderItem
      */
     auto IsDone(double currentFrameTime) const -> bool;
 
+    /**
+     * @brief Returns the current linear blending progress according to the given frame time.
+     * @param currentFrameTime The time in seconds since start of the current frame.
+     * @return The linear blending progress from 0.0 to 1.0.
+     */
+    auto Progress(double currentFrameTime) const -> double;
+
     /**
      * @brief Updates the transition variables and renders the shader quad to the current FBO.
      * @param oldPreset A reference to the old (fading out) preset.

src/libprojectM/Renderer/RenderContext.hpp

@@ -16,16 +16,17 @@ class TextureManager;
 class RenderContext
 {
 public:
-    float time{0.0f};      //!< Time since the preset started, in seconds.
-    int frame{0};          //!< Frames rendered so far.
-    float fps{0.0f};       //!< Frames per second.
-    float progress{0.0f};  //!< Preset progress.
-    int viewportSizeX{0};  //!< Horizontal viewport size in pixels
-    int viewportSizeY{0};  //!< Vertical viewport size in pixels
-    float aspectX{1.0};    //!< X aspect ratio.
-    float aspectY{1.0};    //!< Y aspect ratio.
-    float invAspectX{1.0}; //!< Inverse X aspect ratio.
-    float invAspectY{1.0}; //!< Inverse Y aspect ratio.
+    float time{0.0f};          //!< Time since the preset started, in seconds.
+    int frame{0};              //!< Frames rendered so far.
+    float fps{0.0f};           //!< Frames per second.
+    float progress{0.0f};      //!< Preset progress.
+    float blendProgress{0.0f}; //!< Preset transition/blending progress.
+    int viewportSizeX{0};      //!< Horizontal viewport size in pixels
+    int viewportSizeY{0};      //!< Vertical viewport size in pixels
+    float aspectX{1.0};        //!< X aspect ratio.
+    float aspectY{1.0};        //!< Y aspect ratio.
+    float invAspectX{1.0};     //!< Inverse X aspect ratio.
+    float invAspectY{1.0};     //!< Inverse Y aspect ratio.
 
     int perPixelMeshX{64}; //!< Per-pixel/per-vertex mesh X resolution.
     int perPixelMeshY{48}; //!< Per-pixel/per-vertex mesh Y resolution.