Section: BONUS! Interactive Light

text_and_shaders.cpp

@@ -1,14 +1,54 @@
 #include <orx.h>
 
+orxOBJECT * light_bulb;
+
+// Now we need to keep the viewport in a global variable
+orxVIEWPORT * viewport;
+
+// This method will be called whenever Orx needs the parameters for our shader
+orxSTATUS orxFASTCALL lightPosHandler(const orxEVENT *_pstEvent) {
+    if(_pstEvent->eID == orxSHADER_EVENT_SET_PARAM) {
+        orxSHADER_EVENT_PAYLOAD * payload = (orxSHADER_EVENT_PAYLOAD *)_pstEvent->pstPayload;
+        if(strcmp(payload->zParamName, "LightPos") == 0) {
+            // Here we set the "LightPos" parameter to be the mouse position
+            orxMouse_GetPosition(&(payload->vValue));
+            payload->vValue.fZ = 100;
+        }
+    }
+    return orxSTATUS_SUCCESS;
+}
+
 orxSTATUS orxFASTCALL Init()
 {
-  orxViewport_CreateFromConfig("Viewport");
+  viewport = orxViewport_CreateFromConfig("Viewport");
   orxObject_CreateFromConfig("TextObject");
+
+  // Create the light bulb
+  light_bulb = orxObject_CreateFromConfig("LightBulb");
+
+  // Register our shader parameter handler
+  orxEvent_AddHandler ( orxEVENT_TYPE_SHADER, lightPosHandler);
   return orxSTATUS_SUCCESS;
 }
 
 orxSTATUS orxFASTCALL Run()
 {
+  orxVECTOR mousePos;
+  orxVECTOR mouseInWorld;
+
+  // Get the mouse position on screen
+  orxMouse_GetPosition(&mousePos);
+
+  // Get the mouse position in the game world,
+  // note that the mouse might not be in our game's window
+  orxVECTOR * inWindow = orxRender_GetWorldPosition(&mousePos, viewport, &mouseInWorld);
+  if(inWindow) {
+    mouseInWorld.fZ = -0.1;
+  } else {
+    mouseInWorld.fZ = -2; // Out of camera frustum, so the light_bulb is hidden
+  }
+  orxObject_SetPosition(light_bulb, &mouseInWorld);
+
   return orxSTATUS_SUCCESS;
 }
 

text_and_shaders.ini

@@ -55,6 +55,14 @@ void main() {
 }"
 BorderColor = (0,0,255) ; Let's make the border blue, just for fun.
 LightPos = (200,150,100) ;
-LightColor = (1,0.7,0.7) ;
+LightColor = (1,1,0.18) ;
+UseCustomParam = true ; Since the LightPos parameter will change at runtime we need this.
+
+[LightBulb]
+Graphic = @
+Texture = light_bulb.png
+Pivot = (64,53,0)
+Scale = 0.5
+Position = (0,0,-0.1)
 
 @plump.ini@