Correct graphics scaling logic

3 files changed, 54 insertions, 33 deletions

diff --git a/apps/graphics/traveler/include/trv_graphics.h b/apps/graphics/traveler/include/trv_graphics.h
index 69790e627..b51a8d4fc 100644
--- a/apps/graphics/traveler/include/trv_graphics.h
+++ b/apps/graphics/traveler/include/trv_graphics.h
@@ -86,14 +86,16 @@ struct trv_graphics_info_s
   NXHANDLE hnx;                 /* The connection handle */
   NXHANDLE bgwnd;               /* Background window handle */
 #else
-  trv_coord_t stride;           /* Length of a line in bytes */
+  trv_coord_t hoffset;          /* Horizontal to start of data (in columns) */
+  trv_coord_t voffset;          /* Offset to start of data (in rows) */
+  trv_coord_t stride;           /* Length of a line (in bytes) */
 #endif
   trv_coord_t hwwidth;          /* Display width (pixels) */
   trv_coord_t hwheight;         /* Display height (rows) */
   trv_coord_t swwidth;          /* Software render width (pixels) */
   trv_coord_t swheight;         /* Software render height height (rows) */
-  uint8_t vscale;               /* Log2 vertical image scale factor */
-  uint8_t hscale;               /* Log2 horizontal image scale factor */
+  uint8_t vscale;               /* Vertical image scale factor */
+  uint8_t hscale;               /* Horizontal image scale factor */
   struct trv_palette_s palette; /* Color palette */
   FAR dev_pixel_t *hwbuffer;    /* Hardware frame buffer */
   FAR trv_pixel_t *swbuffer;    /* Software render buffer */
diff --git a/apps/graphics/traveler/include/trv_raycntl.h b/apps/graphics/traveler/include/trv_raycntl.h
index ffcf2b6d3..47bc6bf54 100644
--- a/apps/graphics/traveler/include/trv_raycntl.h
+++ b/apps/graphics/traveler/include/trv_raycntl.h
@@ -41,12 +41,16 @@
  ****************************************************************************/
 
 #include "trv_types.h"
-#include "trv_graphics.h"
 
 /****************************************************************************
  * Pre-processor Definitions
  ****************************************************************************/
 
+/* This is the size of the buffer supported by the ray caster */
+
+#define TRV_SCREEN_WIDTH  320
+#define TRV_SCREEN_HEIGHT 200
+
 /****************************************************************************
  * Public Types
  ****************************************************************************/
@@ -55,6 +59,9 @@
  * Public Function Prototypes
  ****************************************************************************/
 
+struct trv_camera_s;
+struct trv_graphics_info_s;
+
 void trv_raycaster(FAR struct trv_camera_s *player,
                    FAR struct trv_graphics_info_s *ginfo);
 
diff --git a/apps/graphics/traveler/src/trv_graphics.c b/apps/graphics/traveler/src/trv_graphics.c
index 02d9b61b9..19f5b81e5 100644
--- a/apps/graphics/traveler/src/trv_graphics.c
+++ b/apps/graphics/traveler/src/trv_graphics.c
@@ -41,6 +41,7 @@
 #include "trv_main.h"
 #include "trv_mem.h"
 #include "trv_color.h"
+#include "trv_raycntl.h"
 #include "trv_debug.h"
 #include "trv_graphics.h"
 
@@ -329,24 +330,21 @@ void trv_row_update(struct trv_graphics_info_s *ginfo,
                     FAR const trv_pixel_t *src,
                     FAR dev_pixel_t *dest)
 {
-  trv_coord_t hexpand;
   dev_pixel_t pixel;
   trv_coord_t srccol;
   int i;
 
   /* Loop for each column in the src render buffer */
 
-  hexpand = (1 << ginfo->hscale);
-
-  for (srccol = 0; srccol < ginfo->swwidth; srccol++)
+  for (srccol = 0; srccol < TRV_SCREEN_WIDTH; srccol++)
     {
       /* Map the source pixel */
 
       pixel = ginfo->palette.lut[*src++];
 
-      /* Copy it to the destination, expanding as necessary */
+      /* Expand pixels horizontally via pixel replication */
 
-      for (i = 0; i < hexpand; i++)
+      for (i = 0; i < ginfo->hscale; i++)
         {
           *dest++ = pixel;
         }
@@ -383,8 +381,8 @@ void trv_display_update(struct trv_graphics_info_s *ginfo,
 
 int trv_graphics_initialize(FAR struct trv_graphics_info_s *ginfo)
 {
-  int swwidth;
-  int swheight;
+  int width;
+  int height;
   int scale;
 
   /* Initialize the graphics device and get information about the display */
@@ -397,31 +395,38 @@ int trv_graphics_initialize(FAR struct trv_graphics_info_s *ginfo)
   trv_nxsu_initialize(ginfo);
 #endif
 
+  /* Check the size of the display */
+
+  width = ginfo->hwwidth;
+  height = ginfo->hwheight;
+
+  if (width < TRV_SCREEN_WIDTH || height < TRV_SCREEN_HEIGHT)
+    {
+      trv_abort("ERROR: Display is too small\n");
+    }
+
   /* Check if we need to scale the image */
 
-  swwidth = ginfo->hwwidth;
-  scale   = 0;
+  scale = 0;
 
-  while (swwidth > MAX_REND_WIDTH)
+  while (width >= TRV_SCREEN_WIDTH)
     {
-      swwidth >>= 1;
+      width -= TRV_SCREEN_WIDTH;
       scale++;
     }
 
-  ginfo->swwidth = swwidth;
-  ginfo->hscale   = scale;
+  ginfo->hscale  = scale;
+  ginfo->hoffset = (width >> 1);
 
-  swheight = ginfo->hwheight;
-  scale    = 0;
-
-  while (swheight > MAX_REND_WIDTH)
+  scale = 0;
+  while (height >= TRV_SCREEN_HEIGHT)
     {
-      swheight >>= 1;
+      height -= TRV_SCREEN_HEIGHT;
       scale++;
     }
 
-  ginfo->swheight = swheight;
-  ginfo->vscale   = scale;
+  ginfo->vscale  = scale;
+  ginfo->voffset = (height >> 1);
 
   /* Allocate buffers
    *
@@ -431,7 +436,7 @@ int trv_graphics_initialize(FAR struct trv_graphics_info_s *ginfo)
    */
 
    ginfo->swbuffer = (trv_pixel_t*)
-     trv_malloc(swwidth * swheight * sizeof(trv_pixel_t));
+     trv_malloc(TRV_SCREEN_WIDTH * TRV_SCREEN_HEIGHT * sizeof(trv_pixel_t));
    if (!ginfo->swbuffer)
      {
        trv_abort("ERROR: Failed to allocate render buffer\n");
@@ -503,8 +508,8 @@ void trv_graphics_terminate(FAR struct trv_graphics_info_s *ginfo)
 
 void trv_display_update(struct trv_graphics_info_s *ginfo)
 {
-  FAR const uint8_t *src = (FAR const uint8_t *)ginfo->swbuffer;
-  FAR uint8_t *dest = (FAR uint8_t *)ginfo->hwbuffer;
+  FAR const uint8_t *src;
+  FAR uint8_t *dest;
   trv_coord_t srcrow;
 #ifdef CONFIG_NX
   trv_coord_t destrow;
@@ -512,12 +517,19 @@ void trv_display_update(struct trv_graphics_info_s *ginfo)
   FAR uint8_t *first;
   trv_coord_t lnwidth;
 #endif
-  trv_coord_t vexpand;
   int i;
 
-  /* Loop for each row in the srce render buffer */
+  /* Get the star tof the first source row */
+
+  src = (FAR const uint8_t *)ginfo->swbuffer;
+
+  /* Get the start of the first destination row */
+
+  dest = (FAR uint8_t *)ginfo->hwbuffer +
+         (ginfo->hoffset * ginfo->stride) + ginfo->voffset;
+
+  /* Loop for each row in the src render buffer */
 
-  vexpand = (1 << ginfo->vscale);
 #ifdef CONFIG_NX
   destrow = 0;
 #else
@@ -543,7 +555,7 @@ void trv_display_update(struct trv_graphics_info_s *ginfo)
 
       /* Then replicate as many times as is necessary */
 
-      for (i = 1; i < vexpand; i++)
+      for (i = 1; i < ginfo->vscale; i++)
         {
 #ifdef CONFIG_NX
           /* Transfer the row buffer to the NX window */
@@ -560,7 +572,7 @@ void trv_display_update(struct trv_graphics_info_s *ginfo)
 
       /* Point to the next src row */
 
-      src += ginfo->swwidth;
+      src += TRV_SCREEN_WIDTH;
     }
 }