Fix displacement to use full screen buffer, not just viewport.

.gitignore

@@ -41,3 +41,4 @@ res/keeperfx_icon.ico
 /src/ver_defs.h
 keeperfx.log
 crash_log.txt
+.local/

config/fxdata/lenses.cfg

@@ -13,9 +13,11 @@ Name = LENS_WIBBLE
 ; For displacement kind=1, following parameters are:
 ; magnitude and period
 Displacement = 1 9 10
-; Overlay has two parameters: file name of a RAW texture (or name of a custom lens),
-; Alpha transparency scaled 0..255, where 255 is fully opaque
-; Overlay = frac00.raw 0 
+; Overlay effect parameters (can be combined with Mist, which renders first):
+;   1. File name of a RAW texture (or name of a custom lens overlay)
+;   2. Alpha transparency 0..255 (0=transparent, 255=fully opaque)
+; Note: Palette index 255 in overlay files is treated as transparent
+; Overlay = frac00.raw 0
 
 [lens2]
 Name = FISH_EYE
@@ -29,9 +31,17 @@ Displacement = 3 1 1
 
 [lens4]
 Name = MIST_WATER
-; Mist effect has three parameters: file name of a RAW texture (or name of a custom lens),
-; lightness scaled 0..63, and ghost position (irrelevant)
-Mist = frac00.raw 0 0
+; Mist effect parameters:
+;   1. File name of a RAW texture (or name of a custom lens)
+;   2. Lightness scaled 0..63 (0=darkest, 63=lightest)
+;   3. Ghost position 0..255 (transparency effect)
+;   4-7. Optional animation parameters (0..255):
+;        4. Primary layer X movement speed (default: 2)
+;        5. Primary layer Y movement speed (default: 1)
+;        6. Secondary layer X movement speed (default: 253)
+;        7. Secondary layer Y movement speed (default: 3)
+;        Set all to 0 for static/frozen mist (no animation)
+Mist = frac00.raw 0 0 2 1 253 3
 
 [lens5]
 Name = MIST_TWO_LAYERED_WATER

src/config_lenses.c

@@ -58,6 +58,10 @@ const struct NamedField lenses_data_named_fields[] = {
     {"MIST",              0, field(lenses_conf.lenses[0].mist_file),                0,        0,        0, NULL,         value_mist,      assign_null},
     {"MIST",              1, field(lenses_conf.lenses[0].mist_lightness),           0,        0,       63, NULL,         value_default,   assign_default},
     {"MIST",              2, field(lenses_conf.lenses[0].mist_ghost),               0,        0,      255, NULL,         value_default,   assign_default},
+    {"MIST",              3, field(lenses_conf.lenses[0].mist_pos_x_step),          2,        0,      255, NULL,         value_default,   assign_default},
+    {"MIST",              4, field(lenses_conf.lenses[0].mist_pos_y_step),          1,        0,      255, NULL,         value_default,   assign_default},
+    {"MIST",              5, field(lenses_conf.lenses[0].mist_sec_x_step),        253,        0,      255, NULL,         value_default,   assign_default},
+    {"MIST",              6, field(lenses_conf.lenses[0].mist_sec_y_step),          3,        0,      255, NULL,         value_default,   assign_default},
     {"DISPLACEMENT",      0, field(lenses_conf.lenses[0].displace_kind),            0,        0,      255, NULL,         value_default,   assign_default},
     {"DISPLACEMENT",      1, field(lenses_conf.lenses[0].displace_magnitude),       0,        0,      511, NULL,         value_default,   assign_default},
     {"DISPLACEMENT",      2, field(lenses_conf.lenses[0].displace_period),          1,        0,      511, NULL,         value_displace,  assign_default},
@@ -124,11 +128,6 @@ static int64_t value_overlay(const struct NamedField* named_field, const char* v
     lenses_conf.lenses[idx].flags |= LCF_HasOverlay;
     struct LensConfig* lenscfg = &lenses_conf.lenses[idx];
 
-    // Clear mist flag and mist_file if this lens only has an overlay
-    // This prevents garbage mist data from previous lens configurations
-    lenscfg->flags &= ~LCF_HasMist;
-    lenscfg->mist_file[0] = '\0';
-
     // Only store the overlay name when processing position 0 (the name field)
     // Position 1 is the alpha value, handled by value_default
     if (named_field->argnum == 0)

src/config_lenses.h

@@ -45,6 +45,10 @@ struct LensConfig {
     short mist_lightness;
     short mist_ghost;
     char mist_file[DISKPATH_SIZE];
+    short mist_pos_x_step;
+    short mist_pos_y_step;
+    short mist_sec_x_step;
+    short mist_sec_y_step;
     short displace_kind;
     short displace_magnitude;
     short displace_period;

src/lens_api.c

@@ -452,6 +452,8 @@ void setup_eye_lens(long nlens)
     }
     if (nlens == 0)
     {
+        // Switching to no lens - free mist to reset state
+        free_mist();
         game.active_lens_type = 0;
         game.applied_lens_type = 0;
         return;
@@ -461,6 +463,13 @@ void setup_eye_lens(long nlens)
         game.applied_lens_type = nlens;
         return;
     }
+
+    // Clear the spare screen buffer when switching lenses to prevent corruption
+    // This ensures we don't have stale data from previous lens renders
+    if (eye_lens_spare_screen_memory != NULL) {
+        memset(eye_lens_spare_screen_memory, 0, (eye_lens_width * eye_lens_height) * sizeof(TbPixel));
+    }
+
     struct LensConfig* lenscfg = get_lens_config(nlens);
     if ((lenscfg->flags & LCF_HasMist) != 0)
     {        
@@ -494,7 +503,11 @@ void setup_eye_lens(long nlens)
 
         setup_mist((unsigned char *)eye_lens_memory,
             &pixmap.fade_tables[(lenscfg->mist_lightness)*256],
-            &pixmap.ghost[(lenscfg->mist_ghost)*256]);
+            &pixmap.ghost[(lenscfg->mist_ghost)*256],
+            (unsigned char)lenscfg->mist_pos_x_step,
+            (unsigned char)lenscfg->mist_pos_y_step,
+            (unsigned char)lenscfg->mist_sec_x_step,
+            (unsigned char)lenscfg->mist_sec_y_step);
     }
     if ((lenscfg->flags & LCF_HasDisplace) != 0)
     {
@@ -544,11 +557,13 @@ void reinitialise_eye_lens(long nlens)
   SYNCDBG(18,"Finished");
 }
 
-static void draw_displacement_lens(unsigned char *dstbuf, unsigned char *srcbuf, uint32_t *lens_mem, int width, int height, int dstpitch)
+static void draw_displacement_lens(unsigned char *dstbuf, unsigned char *srcbuf, uint32_t *lens_mem, int width, int height, int dstpitch, int lens_pitch)
 {
     SYNCDBG(16,"Starting");
     unsigned char* dst = dstbuf;
     uint32_t* mem = lens_mem;
+    // srcbuf is the full screen buffer - pos_map indexes into it correctly
+    // lens_pitch is the width of the displacement map (full screen width)
     for (int h = 0; h < height; h++)
     {
         for (int w = 0; w < width; w++)
@@ -558,6 +573,8 @@ static void draw_displacement_lens(unsigned char *dstbuf, unsigned char *srcbuf,
             mem++;
         }
         dst += dstpitch;
+        // Skip to the next row in the displacement map if it's wider than our render width
+        mem += (lens_pitch - width);
     }
 }
 
@@ -650,7 +667,7 @@ static void draw_overlay(unsigned char *dstbuf, long dstpitch, long width, long
     }
 }
 
-void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, long srcpitch, long width, long height, long effect)
+void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, long srcpitch, long width, long height, long viewport_x, long effect)
 {
     long copied = 0;
     if ((effect < 1) || (effect > lenses_conf.lenses_count))
@@ -660,9 +677,13 @@ void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbu
         effect = 0;
     }
     struct LensConfig* lenscfg = &lenses_conf.lenses[effect];
+
+    // For sequential operations (mist, copy), offset srcbuf by viewport_x
+    unsigned char* viewport_srcbuf = srcbuf + viewport_x;
+
     if ((lenscfg->flags & LCF_HasMist) != 0)
     {
-        draw_mist(dstbuf, dstpitch, srcbuf, srcpitch, width, height);
+        draw_mist(dstbuf, dstpitch, viewport_srcbuf, srcpitch, width, height);
         copied = true;
     }
     if ((lenscfg->flags & LCF_HasDisplace) != 0)
@@ -671,12 +692,18 @@ void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbu
         {
         case 1:
         case 2:
-            draw_displacement_lens(dstbuf, srcbuf, eye_lens_memory,
-                width, height, dstpitch);
+            // For displacement, use full srcbuf (not offset) because displacement map contains absolute positions
+            // Offset the displacement map to start at the viewport position
+            long full_width = eye_lens_width;
+            uint32_t* viewport_lens_mem = eye_lens_memory + viewport_x;
+            draw_displacement_lens(dstbuf, srcbuf, viewport_lens_mem,
+                width, height, dstpitch, full_width);
             copied = true;
             break;
         case 3:
-            flyeye_blitsec(srcbuf, srcpitch, dstbuf, dstpitch, 1, height);
+            // Flyeye effect uses its own optimized blitting function that handles displacement internally
+            // It also expects the full srcbuf and uses the viewport_x internally for lookups, so we pass the full srcbuf
+            flyeye_blitsec(viewport_srcbuf, srcpitch, dstbuf, dstpitch, 1, height);
             copied = true;
             break;
         }
@@ -691,7 +718,7 @@ void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbu
         // First, copy the source buffer to destination if not already done
         if (!copied)
         {
-            draw_copy(dstbuf, dstpitch, srcbuf, srcpitch, width, height);
+            draw_copy(dstbuf, dstpitch, viewport_srcbuf, srcpitch, width, height);
         }
         // Load overlay if not already loaded
         if (load_overlay_image(effect)) {
@@ -704,7 +731,7 @@ void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbu
     // If we haven't copied the buffer to screen yet, do so now
     if (!copied)
     {
-        draw_copy(dstbuf, dstpitch, srcbuf, srcpitch, width, height);
+        draw_copy(dstbuf, dstpitch, viewport_srcbuf, srcpitch, width, height);
     }
 }
 

src/lens_api.h

@@ -41,7 +41,7 @@ void initialise_eye_lenses(void);
 void setup_eye_lens(long nlens);
 void reinitialise_eye_lens(long nlens);
 void reset_eye_lenses(void);
-void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, long srcpitch, long width, long height, long effect);
+void draw_lens_effect(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, long srcpitch, long width, long height, long viewport_x, long effect);
 /******************************************************************************/
 #ifdef __cplusplus
 }

src/lens_mist.cpp

@@ -30,7 +30,9 @@ class CMistFade {
   public:
     CMistFade(void);
     virtual ~CMistFade(void);
-    void setup(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost);
+    void setup(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost, 
+               unsigned char pos_x_step, unsigned char pos_y_step, 
+               unsigned char sec_x_step, unsigned char sec_y_step);
     void animset(long a1, long a2);
     void mist(unsigned char *dstbuf, long dstwidth, unsigned char *srcbuf, long srcwidth, long width, long height);
     void animate(void);
@@ -56,7 +58,9 @@ class CMistFade {
 CMistFade *mist = NULL;
 /******************************************************************************/
 
-void CMistFade::setup(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost)
+void CMistFade::setup(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost, 
+                      unsigned char pos_x_step, unsigned char pos_y_step, 
+                      unsigned char sec_x_step, unsigned char sec_y_step)
 {
   this->lens_data = lens_mem;
   this->fade_data = fade;
@@ -68,10 +72,10 @@ void CMistFade::setup(unsigned char *lens_mem, unsigned char *fade, unsigned cha
   this->secondary_offset_y = 128;
   this->animation_speed = 1024;
   this->animation_counter = 0;
-  this->position_x_step = 2;
-  this->position_y_step = 1;
-  this->secondary_x_step = 253;
-  this->secondary_y_step = 3;
+  this->position_x_step = pos_x_step;
+  this->position_y_step = pos_y_step;
+  this->secondary_x_step = sec_x_step;
+  this->secondary_y_step = sec_y_step;
 }
 
 void CMistFade::animset(long a1, long a2)
@@ -161,7 +165,7 @@ void CMistFade::mist(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf
 
 CMistFade::CMistFade(void)
 {
-  setup(NULL, NULL, NULL);
+  setup(NULL, NULL, NULL, 2, 1, 253, 3);
 }
 
 CMistFade::~CMistFade(void)
@@ -181,12 +185,14 @@ TbBool draw_mist(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, lo
     return true;
 }
 
-void setup_mist(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost)
+void setup_mist(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost,
+                unsigned char pos_x_step, unsigned char pos_y_step, 
+                unsigned char sec_x_step, unsigned char sec_y_step)
 {
     SYNCDBG(8,"Starting");
     if (mist == NULL)
         mist = new CMistFade();
-    mist->setup(lens_mem, fade, ghost);
+    mist->setup(lens_mem, fade, ghost, pos_x_step, pos_y_step, sec_x_step, sec_y_step);
     mist->animset(0, 1024);
 }
 

src/lens_mist.h

@@ -26,7 +26,9 @@
 extern "C" {
 #endif
 /******************************************************************************/
-void setup_mist(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost);
+void setup_mist(unsigned char *lens_mem, unsigned char *fade, unsigned char *ghost,
+                unsigned char pos_x_step, unsigned char pos_y_step, 
+                unsigned char sec_x_step, unsigned char sec_y_step);
 TbBool draw_mist(unsigned char *dstbuf, long dstpitch, unsigned char *srcbuf, long srcpitch, long width, long height);
 void free_mist(void);
 /******************************************************************************/

src/thing_creature.c

@@ -4286,8 +4286,9 @@ void draw_creature_view(struct Thing *thing)
   // Draw the buffer on real screen using actual viewport dimensions
   setup_engine_window(0, 0, MyScreenWidth, MyScreenHeight);
   // Apply lens effect to the viewport area only (not including sidebar)
+  // Pass full srcbuf so displacement map lookups work correctly
   draw_lens_effect(lbDisplay.WScreen + view_x, lbDisplay.GraphicsScreenWidth, 
-      scrmem + view_x, eye_lens_width, view_width, view_height, game.applied_lens_type);
+      scrmem, eye_lens_width, view_width, view_height, view_x, game.applied_lens_type);
 }
 
 struct Thing *get_creature_near_for_controlling(PlayerNumber plyr_idx, MapCoord x, MapCoord y)