Introduce phantom shape, refactor field

Introduce phantom shape feature, yay!
Refactor field: rename attribute of invisible empty cells, remove
"color" member from struct shape, introduce shape movement functions
with embedded collision checking and success reporting,

6 files changed, 108 insertions, 53 deletions

diff --git a/README.md b/README.md
index d0cf87e..d213330 100644
--- a/README.md
+++ b/README.md
@@ -38,7 +38,7 @@ Look at the [repo releases](https://github.com/Oxore/tetris-csfml/releases)! Now
 - [x] Scoring system as in Tetris for NES which is described on [this page](https://tetris.wiki/Scoring)
 - [Wall kick](https://tetris.wiki/Wall_kick)
 - Hard drop
-- Phantom shape
+- [x] Phantom shape
 - Table of records
 - Settings menu with external `config.yml` file which allows
   - Change key bindings
diff --git a/include/field.h b/include/field.h
index 30ed56b..52b4de8 100644
--- a/include/field.h
+++ b/include/field.h
@@ -1,5 +1,7 @@
-#define FLD_ATTR_INVISIBLE      (1 << 0)
-#define FLD_ATTR_TRANSPARENT    (1 << 1)
+#define FLD_ATTR_INVISIBLE          (1 << 0)
+#define FLD_ATTR_HIDE_EMPTY_CELLS   (1 << 1)
+
+#define SHP_ATTR_GHOST              (1 << 0)
 
 struct cell {
     char a; // active/empty state of cell
@@ -24,11 +26,10 @@ struct cell {
  */
 
 struct shape {
-    int x; // x coord of shape's left side
-    int y; // y coord of shape's bottom
+    struct vector2i; // position
     int t; // shape type
-    unsigned int color; // shape color
-    char c[4][4]; // array of logic shape cells
+    unsigned int attr;
+    char c[4][4];
 };
 
 struct field {
@@ -47,6 +48,9 @@ void field_deinit(struct field *fld);
 void field_fill_random(struct field *fld);
 void field_clear(struct field *fld);
 void field_rotate_shape(struct field *fld, unsigned int index);
+int  field_move_shape_down(struct field *fld, unsigned int index);
+int  field_move_shape_left(struct field *fld, unsigned int index);
+int  field_move_shape_right(struct field *fld, unsigned int index);
 void field_put_shape(struct field *fld, struct shape *shape);
 void field_reset_walking_shape(struct field *fld, unsigned int index);
 int  field_rm_lines(struct field *fld);
diff --git a/src/engine.c b/src/engine.c
index c218105..72fdbfc 100644
--- a/src/engine.c
+++ b/src/engine.c
@@ -160,6 +160,7 @@ static void transition_game_over()
     painter_update_field(nxt.id, &nxt);
 
     fld.shape[0].y = fld.size.y;
+    fld.shape[1].y = fld.size.y;
     field_fill_random(&fld);
     painter_update_field(fld.id, &fld);
 
@@ -169,14 +170,29 @@ static void transition_game_over()
     list_foreach(texts, update_game_text);
 }
 
+static void project_ghost_shape(struct field *fld, unsigned int idreal, unsigned int idghost)
+{
+    fld->shape[idghost].t = fld->shape[idreal].t;
+    fld->shape[idghost].x = fld->shape[idreal].x;
+    fld->shape[idghost].y = fld->shape[idreal].y;
+    for (unsigned int j = 0; j < 4; j++)
+        for (unsigned int i = 0; i < 4; i++)
+            fld->shape[idghost].c[j][i] = fld->shape[idreal].c[j][i];
+    do {
+        --fld->shape[idghost].y;
+    } while (!field_shape_collision(fld, &fld->shape[idghost]));
+    ++fld->shape[idghost].y;
+}
+
 static void transition_put_shape()
 {
-    field_put_shape(&fld, &fld.shape[0]);
+    field_put_shape(&fld, &fld.shape[1]);
     int removedLines = field_rm_lines(&fld);
     game.lines += removedLines;
     game.scoreCurrent += rmlines_score[removedLines] * game.level;
-    fld.shape[0].t = nxt.shape[0].t;
-    field_reset_walking_shape(&fld, 0);
+    fld.shape[1].t = nxt.shape[0].t;
+    field_reset_walking_shape(&fld, 1);
+    project_ghost_shape(&fld, 1, 0);
     for (unsigned int s = 0; s < nxt.shape_cnt - 1; ++s) {
         nxt.shape[s] = nxt.shape[s + 1];
         nxt.shape[s].y = 4 - s * 3;
@@ -188,13 +204,12 @@ static void transition_put_shape()
 static void game_tick()
 {
     sfClock_restart(game.gameTick);
-    fld.shape[0].y--; // try
-    if (field_shape_collision(&fld, &fld.shape[0]))
-        fld.shape[0].y++; // fallback
-    else
+    if (field_move_shape_down(&fld, 1)) {
+        project_ghost_shape(&fld, 1, 0);
         sfClock_restart(game.putTick);
+    }
     if (sfClock_getElapsedTime(game.putTick).microseconds >= PUT_LATENCY) {
-        if (field_shape_out_of_bounds(&fld, &fld.shape[0]))
+        if (field_shape_out_of_bounds(&fld, &fld.shape[1]))
             transition_game_over();
         else
             transition_put_shape();
@@ -204,15 +219,14 @@ static void game_tick()
 
 static void signal_up()
 {
-    field_rotate_shape(&fld, 0);
+    field_rotate_shape(&fld, 1);
+    project_ghost_shape(&fld, 1, 0);
 }
 
 static void signal_down()
 {
-    fld.shape[0].y--;
-    if (field_shape_collision(&fld, &fld.shape[0])) {
-        fld.shape[0].y++;
-    } else {
+    if (field_move_shape_down(&fld, 1)) {
+        project_ghost_shape(&fld, 1, 0);
         sfClock_restart(game.gameTick);
         game.scoreCurrent++;
     }
@@ -221,21 +235,19 @@ static void signal_down()
 
 static void signal_left()
 {
-    fld.shape[0].x--;
-    if (field_shape_collision(&fld, &fld.shape[0]))
-        fld.shape[0].x++;
-    else
+    if (field_move_shape_left(&fld, 1)) {
+        project_ghost_shape(&fld, 1, 0);
         sfClock_restart(game.putTick);
+    }
     sfClock_restart(game.repKeyLeft);
 }
 
 static void signal_right()
 {
-    fld.shape[0].x++;
-    if (field_shape_collision(&fld, &fld.shape[0]))
-        fld.shape[0].x--;
-    else
+    if (field_move_shape_right(&fld, 1)) {
+        project_ghost_shape(&fld, 1, 0);
         sfClock_restart(game.putTick);
+    }
     sfClock_restart(game.repKeyRight);
 }
 
@@ -322,8 +334,10 @@ static void transition_game_start()
 {
     game.isStarted = 1;
     field_clear(&fld);
-    shape_gen_random(&fld.shape[0]);
-    field_reset_walking_shape(&fld, 0);
+    shape_gen_random(&fld.shape[1]);
+    field_reset_walking_shape(&fld, 1);
+    project_ghost_shape(&fld, 1, 0);
+    shape_load(&fld.shape[1]);
     for (unsigned int i = 0; i < nxt.shape_cnt; ++i)
         shape_gen_random(&nxt.shape[i]);
     nxt.attr &= ~FLD_ATTR_INVISIBLE;
diff --git a/src/field.c b/src/field.c
index 18b4fed..62b6455 100644
--- a/src/field.c
+++ b/src/field.c
@@ -29,6 +29,13 @@ void field_init(struct field *fld)
     fld->shape = calloc(fld->shape_cnt, sizeof(struct shape));
 }
 
+void field_deinit(struct field *fld) {
+    for (int j = 0; j < (int)fld->bound.y; j++)
+        free(fld->c[j]);
+    free(fld->c);
+    free(fld->shape);
+}
+
 void field_clear(struct field *fld)
 {
     for (unsigned int j = 0; j < fld->bound.y; j++)
@@ -53,7 +60,7 @@ void field_put_shape(struct field *fld, struct shape *active)
         for (int i = 0; i < 4; i++)
             if (active->c[j][i]) {
                 fld->c[j+active->y][i+active->x].a = active->c[j][i];
-                fld->c[j+active->y][i+active->x].color = active->color;
+                fld->c[j+active->y][i+active->x].color = active->t;
             }
 }
 
@@ -68,7 +75,6 @@ int field_shape_out_of_bounds(struct field *fld, struct shape *active)
 
 void shape_load(struct shape *shape)
 {
-    shape->color = shape->t;
     switch (shape->t) { // Copy cell active/inactive state
         case 1 :
             memcpy(&shape->c[0][0], &arrShapeL[0][0], sizeof(char)*4*4);
@@ -96,15 +102,15 @@ void shape_load(struct shape *shape)
 
 void field_reset_walking_shape(struct field *fld, unsigned int index)
 {
-    struct shape *active = &fld->shape[index];
-    shape_load(active);
-    active->x = 3;
-    if (active->t == 6)
-        active->y = 19;
+    struct shape *shape = &fld->shape[index];
+    shape_load(shape);
+    shape->x = 3;
+    if (shape->t == 6)
+        shape->y = 19;
     else
-        active->y = 18;
-    while (field_shape_collision(fld, active))
-        active->y++;
+        shape->y = 18;
+    while (field_shape_collision(fld, shape))
+        shape->y++;
 }
 
 void shape_gen_random(struct shape *shape)
@@ -181,6 +187,36 @@ void field_rotate_shape(struct field *fld, unsigned int index)
         rotate_shape_left(shape);
 }
 
+int field_move_shape_down(struct field *fld, unsigned int index)
+{
+    fld->shape[index].y--;
+    if (field_shape_collision(fld, &fld->shape[index])) {
+        fld->shape[index].y++;
+        return 0;
+    }
+    return -1;
+}
+
+int field_move_shape_left(struct field *fld, unsigned int index)
+{
+    fld->shape[index].x--;
+    if (field_shape_collision(fld, &fld->shape[index])) {
+        fld->shape[index].x++;
+        return 0;
+    }
+    return -1;
+}
+
+int field_move_shape_right(struct field *fld, unsigned int index)
+{
+    fld->shape[index].x++;
+    if (field_shape_collision(fld, &fld->shape[index])) {
+        fld->shape[index].x--;
+        return 0;
+    }
+    return -1;
+}
+
 int field_rm_lines(struct field *fld)
 {
     unsigned int lines = 0;
@@ -201,10 +237,3 @@ int field_rm_lines(struct field *fld)
     }
     return lines;
 }
-
-void field_deinit(struct field *fld) {
-    for (int j = 0; j < (int)fld->bound.y; j++)
-        free(fld->c[j]);
-    free(fld->c);
-    free(fld->shape);
-}
diff --git a/src/main.c b/src/main.c
index 6eafc6e..df98a0b 100644
--- a/src/main.c
+++ b/src/main.c
@@ -70,14 +70,15 @@ int main()
     fld.pos = FLD_POS;
     fld.size = (struct vector2ui){.x = FLD_SIZE_X, .y = FLD_SIZE_Y};
     fld.bound = (struct vector2ui){.x = FLD_BOUND_X, .y = FLD_BOUND_Y};
-    fld.shape_cnt = 1;
+    fld.shape_cnt = 2;
     field_init(&fld);
+    fld.shape[0].attr |= SHP_ATTR_GHOST;
 
     nxt.pos = NXT_POS;
     nxt.size = NXT_SIZE;
     nxt.bound = NXT_SIZE;
     nxt.shape_cnt = 3;
-    nxt.attr |= FLD_ATTR_TRANSPARENT | FLD_ATTR_INVISIBLE;
+    nxt.attr |= FLD_ATTR_HIDE_EMPTY_CELLS | FLD_ATTR_INVISIBLE;
     field_init(&nxt);
     nxt.shape[0].y = 4;
     nxt.shape[1].y = 1;
diff --git a/src/painter.c b/src/painter.c
index 9f6b911..c0e93ea 100644
--- a/src/painter.c
+++ b/src/painter.c
@@ -120,7 +120,7 @@ void painter_update_field(unsigned long id, struct field *fld)
             if (fld->c[j][i].a) {
                 sfRectangleShape_setFillColor(f->p[j][i], shape_color_map[fld->c[j][i].color]);
                 sfRectangleShape_setOutlineColor(f->p[j][i], (sfColor)UIFGACTIVECOLOR);
-            } else if (f->attr & FLD_ATTR_TRANSPARENT) {
+            } else if (f->attr & FLD_ATTR_HIDE_EMPTY_CELLS) {
                 sfRectangleShape_setFillColor(f->p[j][i], (sfColor)UITRANSPARENT);
                 sfRectangleShape_setOutlineColor(f->p[j][i], (sfColor)UITRANSPARENT);
             } else {
@@ -129,17 +129,24 @@ void painter_update_field(unsigned long id, struct field *fld)
             }
         }
     }
-    for (unsigned int s = 0; s < fld->shape_cnt; ++s)
+    for (unsigned int s = 0; s < fld->shape_cnt; ++s) {
+        sfColor fill_color = shape_color_map[fld->shape[s].t];
+        sfColor outline_color = (sfColor)UIFGACTIVECOLOR;
+        if (fld->shape[s].attr && SHP_ATTR_GHOST) {
+            fill_color.a = 100;
+            outline_color.a = 100;
+        }
         for (int j = 0; j < 4; j++)
             for (int i = 0; i < 4; i++)
                 if (fld->shape[s].c[j][i] && j + fld->shape[s].y < (int)fld->size.y) {
                     sfRectangleShape_setFillColor(
                             f->p[j + fld->shape[s].y][i + fld->shape[s].x],
-                            shape_color_map[fld->shape[s].color]);
+                            fill_color);
                     sfRectangleShape_setOutlineColor(
                             f->p[j + fld->shape[s].y][i + fld->shape[s].x],
-                            (sfColor)UIFGACTIVECOLOR);
+                            outline_color);
                 }
+    }
 }
 
 static void draw_field_drawable(struct drawable *d)