From 74786231c547e9c555f0f1a650f9184c0bdf0e93 Mon Sep 17 00:00:00 2001
From: SarahW <SarahW@localhost>
Date: Fri, 8 Apr 2016 21:40:15 +0100
Subject: [PATCH] Added Voodoo depth biasing.

---
 src/vid_voodoo.c                | 7 ++++++-
 src/vid_voodoo_codegen_x86-64.h | 9 +++++++++
 src/vid_voodoo_codegen_x86.h    | 9 +++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/src/vid_voodoo.c b/src/vid_voodoo.c
index 35fe473..9c430ac 100644
--- a/src/vid_voodoo.c
+++ b/src/vid_voodoo.c
@@ -594,7 +594,9 @@ enum
         FBZ_DRAW_FRONT = 0x0000,
         FBZ_DRAW_BACK  = 0x4000,
         FBZ_DRAW_MASK  = 0xc000,
-        
+
+        FBZ_DEPTH_BIAS = (1 << 16),
+                
         FBZ_PARAM_ADJUST = (1 << 26)
 };
 
@@ -1962,6 +1964,9 @@ static void voodoo_half_triangle(voodoo_t *voodoo, voodoo_params_t *params, vood
                                 else
                                         new_depth = CLAMP16(state->z >> 12);
                                 
+                                if (params->fbzMode & FBZ_DEPTH_BIAS)
+                                        new_depth = (new_depth + params->zaColor) & 0xffff;
+                                
                                 if (params->fbzMode & FBZ_DEPTH_ENABLE)
                                 {
                                         uint16_t old_depth = aux_mem[x];
diff --git a/src/vid_voodoo_codegen_x86-64.h b/src/vid_voodoo_codegen_x86-64.h
index 8794d93..8155127 100644
--- a/src/vid_voodoo_codegen_x86-64.h
+++ b/src/vid_voodoo_codegen_x86-64.h
@@ -231,6 +231,15 @@ static inline void voodoo_generate(uint8_t *code_block, voodoo_t *voodoo, voodoo
                 addbyte(0xc3);
         }
 
+        if (params->fbzMode & FBZ_DEPTH_BIAS)
+        {
+                addbyte(0x03); /*ADD EAX, params->zaColor[ESI]*/
+                addbyte(0x86);
+                addlong(offsetof(voodoo_params_t, zaColor));                
+                addbyte(0x25); /*AND EAX, 0xffff*/
+                addlong(0xffff);
+        }
+
         addbyte(0x89); /*MOV state->new_depth[EDI], EAX*/
         addbyte(0x87);
         addlong(offsetof(voodoo_state_t, new_depth));
diff --git a/src/vid_voodoo_codegen_x86.h b/src/vid_voodoo_codegen_x86.h
index 23a2845..11f87b2 100644
--- a/src/vid_voodoo_codegen_x86.h
+++ b/src/vid_voodoo_codegen_x86.h
@@ -212,6 +212,15 @@ static inline void voodoo_generate(uint8_t *code_block, voodoo_t *voodoo, voodoo
                 addbyte(0x47);
                 addbyte(0xc3);
         }
+        
+        if (params->fbzMode & FBZ_DEPTH_BIAS)
+        {
+                addbyte(0x03); /*ADD EAX, params->zaColor[ESI]*/
+                addbyte(0x86);
+                addlong(offsetof(voodoo_params_t, zaColor));                
+                addbyte(0x25); /*AND EAX, 0xffff*/
+                addlong(0xffff);
+        }
 
         addbyte(0x89); /*MOV state->new_depth[EDI], EAX*/
         addbyte(0x87);