Add ribbon mod

mods/ribbon.diff

@@ -0,0 +1,176 @@
+Licar mod that adds a simple visual effect, a kind of ribbon light trail.
+
+diff --git a/game.h b/game.h
+index b1db32c..e9db9be 100644
+--- a/game.h
++++ b/game.h
+@@ -335,6 +335,7 @@ struct
+   uint32_t frame;                    ///< Current frame number.
+   uint32_t nextRenderFrameTime;      ///< At which frame to render next frame.
+   uint32_t nextRacingTickTime;       ///< When to simulate next physics tick.
++  uint32_t nextRibbonTime;
+   uint8_t cameraMode;
+   uint8_t musicOn;
+   uint8_t keyStates[LCR_KEYS_TOTAL]; /**< Assures unchanging key states
+@@ -1102,6 +1103,7 @@ void LCR_gameInit(int argc, const char **argv)
+   LCR_game.musicOn = LCR_SETTING_MUSIC;
+   LCR_game.nextRenderFrameTime = 0;
+   LCR_game.nextRacingTickTime = 0;
++  LCR_game.nextRibbonTime = 0;
+   LCR_game.cameraMode = LCR_CAMERA_MODE_DRIVE;
+   LCR_currentMap.blockCount = 0; // means no map loaded
+ 
+@@ -1771,6 +1773,9 @@ uint8_t LCR_gameStep(uint32_t time)
+ 
+       uint32_t events = paused ? 0 : LCR_racingStep(input);
+ 
++      if (LCR_racing.tick % LCR_SETTING_RIBBON_INTERVAL == 0)
++        LCR_rendererRibbonUpdate();
++
+ #if LCR_SETTING_PARTICLES
+       LCR_rendererSetParticles(0);
+ 
+diff --git a/renderer.h b/renderer.h
+index 735644e..6941398 100644
+--- a/renderer.h
++++ b/renderer.h
+@@ -153,6 +153,9 @@ struct
+ #if LCR_SETTING_PARTICLES
+   uint_fast16_t particleColor;      ///< 0x0000 means no particles active.
+ #endif
++
++  int16_t ribbonPoints[LCR_SETTING_RIBBON_SEGMENTS * 3];
++  uint8_t ribbonLastSegment;
+ } LCR_renderer;
+ 
+ /**
+@@ -200,6 +203,23 @@ void LCR_rendererSetGhostTransform(LCR_GameUnit position[3],
+   _LCR_rendererSetModelTransform(LCR_renderer.ghostModel,position,rotation);
+ }
+ 
++void LCR_rendererRibbonUpdate(void)
++{
++  LCR_renderer.ribbonLastSegment =
++    (LCR_renderer.ribbonLastSegment + 1) % LCR_SETTING_RIBBON_SEGMENTS;
++
++  unsigned int n = 3 * LCR_renderer.ribbonLastSegment;
++
++  LCR_renderer.ribbonPoints[n] =
++    LCR_renderer.carModel->transform.translation.x / 2;
++  n++;
++  LCR_renderer.ribbonPoints[n] =
++    LCR_renderer.carModel->transform.translation.y / 2;
++  n++;
++  LCR_renderer.ribbonPoints[n] =
++    LCR_renderer.carModel->transform.translation.z / 2;
++}
++
+ void LCR_rendererSetCarVisibility(uint8_t visible)
+ {
+   LCR_renderer.carModel->config.visible = visible;
+@@ -2154,6 +2174,59 @@ void LCR_rendererSetWheelState(LCR_GameUnit rotation, LCR_GameUnit steer)
+ #endif
+ }
+ 
++void LCR_rendererDrawRibbon(void)
++{
++  S3L_Vec4 p, r;
++  int16_t *s = // this will go backwards
++    LCR_renderer.ribbonPoints + 3 * LCR_renderer.ribbonLastSegment + 2;
++  int16_t prev[3]; // previous values for interpolation: screen x, y and size
++
++  p.x = LCR_renderer.carModel->transform.translation.x;
++  p.y = LCR_renderer.carModel->transform.translation.y;
++  p.z = LCR_renderer.carModel->transform.translation.z;
++  p.w = (LCR_SETTING_RIBBON_SIZE * LCR_SETTING_RESOLUTION_X) / 100;
++
++  S3L_project3DPointToScreen(p,LCR_renderer.scene.camera,&r);
++
++  prev[0] = r.x;
++  prev[1] = r.y;
++  prev[2] = r.w;
++
++  for (int i = 0; i < LCR_SETTING_RIBBON_SEGMENTS; ++i)
++  {
++    p.z = *s * 2; s--;
++    p.y = *s * 2; s--;
++    p.x = *s * 2; s--;
++    p.w = (LCR_SETTING_RIBBON_SIZE * LCR_SETTING_RESOLUTION_X) / 100;
++
++    // reducing size towards the tail:
++    p.w = (p.w * (LCR_SETTING_RIBBON_SEGMENTS - 1 - i))
++      / LCR_SETTING_RIBBON_SEGMENTS;
++
++    if (s <= LCR_renderer.ribbonPoints) // wrap to the end
++      s = LCR_renderer.ribbonPoints + (LCR_SETTING_RIBBON_SEGMENTS - 1) * 3 + 2;
++
++    S3L_project3DPointToScreen(p,LCR_renderer.scene.camera,&r);
++
++    for (int j = 0; j < LCR_SETTING_RIBBON_SUBDIV; ++j)
++    {
++      int w = prev[2] + (j * (r.w - prev[2])) / LCR_SETTING_RIBBON_SUBDIV;
++      int x = prev[0] + (j * (r.x - prev[0])) / LCR_SETTING_RIBBON_SUBDIV
++        - w / 2;
++      int y = prev[1] + (j * (r.y - prev[1])) / LCR_SETTING_RIBBON_SUBDIV
++        - w / 2;
++
++      if (w > 0 && x > 0 && y > 0 &&
++        x < LCR_EFFECTIVE_RESOLUTION_X && y < LCR_EFFECTIVE_RESOLUTION_Y)
++        LCR_rendererDrawRect(x,y,w,w,LCR_SETTING_RIBBON_COLOR,1);
++    }
++
++    prev[0] = r.x;
++    prev[1] = r.y;
++    prev[2] = r.w;
++  }
++}
++
+ void LCR_rendererDraw3D(void)
+ {
+   LCR_LOG2("rendering frame (start)");
+@@ -2304,6 +2377,8 @@ void LCR_rendererDraw3D(void)
+ 
+ #endif
+ 
++  LCR_rendererDrawRibbon();
++
+   LCR_LOG2("3D rendering (end)");
+   LCR_LOG2("rendering frame (end)");
+ }
+diff --git a/settings.h b/settings.h
+index 332df45..47e27f8 100644
+--- a/settings.h
++++ b/settings.h
+@@ -200,6 +200,32 @@
+   #define LCR_SETTING_COUNTDOWN_MS 2200
+ #endif
+ 
++#ifndef LCR_SETTING_RIBBON_SEGMENTS
++  /** Ribbon mod: how many points to spawn. */
++  #define LCR_SETTING_RIBBON_SEGMENTS 10
++#endif
++
++#ifndef LCR_SETTING_RIBBON_SUBDIV
++  /** Ribbon mod: number of splats to draw per segment, it's good to keep this a
++    power of 2. */
++  #define LCR_SETTING_RIBBON_SUBDIV 16
++#endif
++
++#ifndef LCR_SETTING_RIBBON_INTERVAL
++  /** Ribbon mod: how often to spawn a new ribbon point (in physics ticks). */
++  #define LCR_SETTING_RIBBON_INTERVAL 4
++#endif
++
++#ifndef LCR_SETTING_RIBBON_SIZE
++  /** Ribbon mod: ribbon splat size (in percents of screen width). */
++  #define LCR_SETTING_RIBBON_SIZE 6
++#endif
++
++#ifndef LCR_SETTING_RIBBON_COLOR
++  /** Ribbon mod: ribbon color. */
++  #define LCR_SETTING_RIBBON_COLOR 0xffe6
++#endif
++
+ #ifndef LCR_SETTING_MAP_CHUNK_RELOAD_INTERVAL
+   /** Interval in rendering frames of reloading map chunks, should ideally be
+     kept a power of two, can't be 0. */