Code cleanup, final fix for sprite lag problem.

[thunder] / src / screen.cpp

diff --git a/src/screen.cpp b/src/screen.cpp
index d3f5672c214db805ef7779b2e120f6a7c34e933e..f08927073766ea2f26c7b9cda0fcaca437a5a2ca 100644 (file)
--- a/src/screen.cpp
+++ b/src/screen.cpp
@@ -41,7 +41,6 @@ uint8_t spr_color_index;              // Sprite color index
 
 extern bool show_text;                 // Whether or not to show text
 
-
 //
 // Render the NAMCO screen
 //
@@ -109,7 +108,6 @@ PP = which 4K block to write to?
        RenderScreenBuffer();
 }
 
-
 //
 // Render tilemap
 //
@@ -121,14 +119,10 @@ static inline void DrawScreen(uint16_t ramBlock, uint16_t xAddress, uint16_t yAd
        for(uint8_t sy=0; sy<29; sy++)
        {
                for(uint8_t sx=0; sx<37; sx++)
-               {
-
                        DrawChar(sx, sy, ramBase, tileBase << 16, xAddress & 0x07, yAddress & 0x07, transparent);
-               }
        }
 }
 
-
 //
 // Draw character on screen
 //
@@ -174,10 +168,8 @@ static inline void DrawChar(uint8_t sx, uint8_t sy, uint16_t ramBase, uint32_t t
        }
 }
 
-
 //
 // Copy sprites in sprite RAM from positions 4-9 to 10-15
-// (N.B.: This still doesn't solve the shifting signs on the walls problem...)
 //
 void CopySprites(void)
 {
@@ -192,9 +184,10 @@ void CopySprites(void)
        }
 }
 
-
 //
-// Draw sprites at priority level (new code)
+// Draw sprites at priority level
+// We read from the sprite copy RAM to render sprites, as that seems to be the
+// way the real H/W does it.
 //
 void DrawSprites(uint8_t priority)
 {
@@ -202,42 +195,44 @@ void DrawSprites(uint8_t priority)
 //
 // Offset  Note
 // ------  --------------------------------------------------------------------
-// 4       h.fb .nnn (f = horz. flip, h = horz. expand, b = sprite offset lo
+// 4 (10)  h.fb .nnn (f = horz. flip, h = horz. expand, b = sprite offset lo
 //         bit, nnn = upper bits of sprite #)
-// 5       Lower 7 bits of sprite #
-// 6       Sprite color index (top 7 bits only), bottom bit is bit 8 of X
+// 5 (11)  Lower 7 bits of sprite #
+// 6 (12)  Sprite color index (top 7 bits only), bottom bit is bit 8 of X
 //         position
-// 7       Sprite X position (bits 0-7)
-// 8       Top two bits are sprite priority, bits 4 & 2 are sprite offset hi
+// 7 (13)  Sprite X position (bits 0-7)
+// 8 (14)  Top two bits are sprite priority, bits 4 & 2 are sprite offset hi
 //         bit, vert. expand
-// 9       Sprite Y position (192 - value)
+// 9 (15)  Sprite Y position (192 - value)
 
-       extern uint8_t gram1[];                                                 // Game RAM space
+       extern uint8_t gram1[];                                 // Game RAM space
 
        for(uint16_t i=0x5800; i<0x6000; i+=0x10)
        {
-               if ((gram1[i + 8 + 6] & 0xC0) == priority)              // Check for correct layer...
-               {
-                       spr_color_index = gram1[i + 6 + 6] >> 1;        // Set color...
-                       uint16_t x = ((gram1[i + 6 + 6] & 0x01) << 8) | gram1[i + 7 + 6];
+               uint8_t * sprRAM = &gram1[i];
 
-                       if (x > 512 - 32)
-                               x -= 512;                                                       // Handle neg x values
+               // Skip sprite if it's not on the correct layer...
+               if ((sprRAM[14] & 0xC0) != priority)
+                       continue;
 
-                       uint16_t y = 192 - gram1[i + 9 + 6];
-                       uint8_t flip = gram1[i + 4 + 6] & 0x20;         // Horizontal flip
-                       uint32_t spr_num = ((gram1[i + 4 + 6] & 0x07) << 9)
-                               | ((gram1[i + 5 + 6] & 0x7F) << 2)
-                               | ((gram1[i + 4 + 6] & 0x10) >> 4)
-                               | ((gram1[i + 8 + 6] & 0x10) >> 3);
+               spr_color_index = sprRAM[12] >> 1;      // Set color...
+               uint16_t x = ((sprRAM[12] & 0x01) << 8) | sprRAM[13];
 
-                       // Draw sprite...
-                       Sprite(spr_num, x, y, flip, gram1[i + 4 + 6] & 0x80, gram1[i + 8 + 6] & 0x04);
-               }
+               if (x > 512 - 32)
+                       x -= 512;                                               // Handle neg x values
+
+               uint16_t y = 192 - sprRAM[15];
+               uint8_t horzFlip = sprRAM[10] & 0x20;
+               uint32_t spr_num = ((sprRAM[10] & 0x07) << 9)
+                       | ((sprRAM[11] & 0x7F) << 2)
+                       | ((sprRAM[10] & 0x10) >> 4)
+                       | ((sprRAM[14] & 0x10) >> 3);
+
+               // Draw the sprite...
+               Sprite(spr_num, x, y, horzFlip, sprRAM[10] & 0x80, sprRAM[14] & 0x04);
        }
 }
 
-
 static inline void DrawSpriteBlock(uint32_t & sprnum, uint16_t x, uint16_t y, uint16_t xStart, uint16_t xEnd, int16_t xInc)
 {
        extern uint8_t spr_rom[];
@@ -263,7 +258,6 @@ static inline void DrawSpriteBlock(uint32_t & sprnum, uint16_t x, uint16_t y, ui
        }
 }
 
-
 static inline void DrawSpriteBlock2(uint32_t & sprnum, uint16_t x, uint16_t y, uint16_t xStart, uint16_t xEnd, int16_t xInc)
 {
        extern uint8_t spr_rom[];
@@ -289,7 +283,6 @@ static inline void DrawSpriteBlock2(uint32_t & sprnum, uint16_t x, uint16_t y, u
        }
 }
 
-
 //
 // Sprite handler
 //
@@ -343,7 +336,6 @@ void Sprite(uint32_t sprnum, uint16_t x, uint16_t y, uint8_t flip,
        }
 }
 
-
 int FindPCXName(void)
 {
        static int pcxNum = -1; // This needs to go elsewhere... (or does it?)
@@ -366,7 +358,6 @@ int FindPCXName(void)
        return -1;
 }
 
-
 void SavePCXSnapshot(void)
 {
        char filename[30];
@@ -465,4 +456,3 @@ void SavePCXSnapshot(void)
        // Success!
        fclose(fw);
 }
-