parsons/ParsonsMasterSystem2026
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases 3 Wiki Activity

Implemenmted rendering priorities

Browse Source
This commit is contained in:
Marc Parsons
2026-05-12 00:30:28 +01:00
parent f825e102a2
commit 95ac0ec7c1
5 changed files with 125 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

58
Core/Video/SmsVdp.cs
View File

@@ -9,6 +9,7 @@ namespace Core.Video
public byte[] CRAM { get; private set; } = new byte[0x20]; // 32 Bytes Color Palette
public byte[] Registers { get; private set; } = new byte[16]; // 11 Hardware Control Registers
public int[] FrameBuffer { get; private set; } = new int[256 * 192];
private bool[] _priorityBuffer = new bool[256 * 192]; // Tracks priority pixels!
// The Control Port State Machine (Port 0xBF)
private bool _isSecondControlByte = false;
@@ -131,18 +132,19 @@ namespace Core.Video
private void RenderBackground()
{
ushort nameTableBase = (ushort)((Registers[2] & 0x0E) << 10);
byte scrollX = Registers[8];
byte scrollY = Registers[9];
bool lockRowScroll = (Registers[0] & 0x80) != 0; // Top 2 rows (Y < 16)
bool lockColScroll = (Registers[0] & 0x40) != 0; // Right 8 columns (X >= 192)
bool lockRowScroll = (Registers[0] & 0x80) != 0;
bool lockColScroll = (Registers[0] & 0x40) != 0;
// Clear the priority mask for the new frame!
Array.Clear(_priorityBuffer, 0, _priorityBuffer.Length);
for (int screenY = 0; screenY < 192; screenY++)
{
for (int screenX = 0; screenX < 256; screenX++)
{
// Apply Vertical Scrolling (Depends on X for column locking!)
int effectiveScrollY = scrollY;
if (lockColScroll && screenX >= 192) effectiveScrollY = 0;
@@ -150,7 +152,6 @@ namespace Core.Video
int row = vdpY / 8;
int tileY = vdpY % 8;
// Apply Horizontal Scrolling (Depends on Y for row locking!)
int effectiveScrollX = scrollX;
if (lockRowScroll && screenY < 16) effectiveScrollX = 0;
@@ -158,31 +159,34 @@ namespace Core.Video
int col = vdpX / 8;
int tileX = vdpX % 8;
// 1. Read the 16-bit Tile instruction from the Name Table
// 1. Read the 16-bit Tile instruction
ushort nameTableAddr = (ushort)(nameTableBase + (row * 64) + (col * 2));
byte lowByte = VRAM[nameTableAddr];
byte highByte = VRAM[nameTableAddr + 1];
ushort tileData = (ushort)((highByte << 8) | lowByte);
// 2. Extract Tile Index and Palette Info
// 2. EXTRACT ALL THE HARDWARE BITS!
int tileIndex = tileData & 0x01FF;
bool useSpritePalette = (tileData & 0x0800) != 0;
bool flipH = (tileData & 0x0200) != 0; // Bit 9
bool flipV = (tileData & 0x0400) != 0; // Bit 10
bool useSpritePalette = (tileData & 0x0800) != 0; // Bit 11
bool priority = (tileData & 0x1000) != 0; // Bit 12
// 3. Find the tile data in VRAM
// 3. Apply Vertical Flip (Read from the bottom of the tile instead of the top)
int readY = flipV ? (7 - tileY) : tileY;
ushort tileAddress = (ushort)(tileIndex * 32);
// 4. Fetch the 4 bitplanes
byte bp0 = VRAM[tileAddress + (tileY * 4) + 0];
byte bp1 = VRAM[tileAddress + (tileY * 4) + 1];
byte bp2 = VRAM[tileAddress + (tileY * 4) + 2];
byte bp3 = VRAM[tileAddress + (tileY * 4) + 3];
byte bp0 = VRAM[tileAddress + (readY * 4) + 0];
byte bp1 = VRAM[tileAddress + (readY * 4) + 1];
byte bp2 = VRAM[tileAddress + (readY * 4) + 2];
byte bp3 = VRAM[tileAddress + (readY * 4) + 3];
// 5. Extract color index
int shift = 7 - tileX;
int colorIndex = ((bp0 >> shift) & 1) |
(((bp1 >> shift) & 1) << 1) |
(((bp2 >> shift) & 1) << 2) |
(((bp3 >> shift) & 1) << 3);
// 4. Apply Horizontal Flip (Shift from right-to-left instead of left-to-right)
int readX = flipH ? tileX : (7 - tileX);
int colorIndex = ((bp0 >> readX) & 1) |
(((bp1 >> readX) & 1) << 1) |
(((bp2 >> readX) & 1) << 2) |
(((bp3 >> readX) & 1) << 3);
int paletteOffset = useSpritePalette ? 16 : 0;
byte smsColor = CRAM[paletteOffset + colorIndex];
@@ -191,7 +195,16 @@ namespace Core.Video
int g = ((smsColor >> 2) & 0x03) * 85;
int b = ((smsColor >> 4) & 0x03) * 85;
FrameBuffer[(screenY * 256) + screenX] = (255 << 24) | (r << 16) | (g << 8) | b;
int screenAddress = (screenY * 256) + screenX;
FrameBuffer[screenAddress] = (255 << 24) | (r << 16) | (g << 8) | b;
// 5. FLAG THE PRIORITY PIXEL!
// If this tile has priority AND the pixel isn't transparent (color 0),
// tell the sprite renderer not to draw over it!
if (priority && colorIndex != 0)
{
_priorityBuffer[screenAddress] = true;
}
}
}
}
@@ -262,6 +275,9 @@ namespace Core.Video
// If the color index is 0, DO NOT draw it! Let the background show through.
if (colorIndex == 0) continue;
// If the background tile at this exact pixel claimed priority, hide the sprite!
if (_priorityBuffer[(screenY * 256) + screenX]) continue;
// Sprites ALWAYS use the second half of CRAM (Palette 1: Indices 16-31)
byte smsColor = CRAM[16 + colorIndex];