add depth prepass in preparation for moving from deferred back to forward renderer

betterRenderer/shaders/default_vertex.hlsl

@@ -7,6 +7,12 @@ struct VertexInput {
   float4 m_Tangent : Tangent;
 };
 
+#ifdef PREPASS
+struct VertexOutput {
+  float2 m_TexCoord : TexCoord;
+  float4 m_PositionSV : SV_Position;
+};
+#else
 struct VertexOutput {
   float3 m_Position : Position;
   float3 m_Normal : Normal;
@@ -16,6 +22,7 @@ struct VertexOutput {
   float4 m_PositionCS : PositionCS;
   float4 m_HistoryPositionCS : HistoryPositionCS;
 };
+#endif
 
 cbuffer VertexConstants : register(b0) {
   float4x4 g_JitteredProjection;
@@ -29,14 +36,17 @@ VertexOutput main(in VertexInput vs_in) {
   VertexOutput result;
   float4x3 model_view = GetModelView();
   float4x3 model_view_history = GetModelViewHistory();
-  result.m_Position = mul(float4(vs_in.m_Position, 1.), model_view).xyz;
-  result.m_Normal = mul(float4(vs_in.m_Normal, 0.), model_view).xyz;
+  float3 view_space_position = mul(float4(vs_in.m_Position, 1.), model_view).xyz;
   result.m_TexCoord = vs_in.m_TexCoord;
+  result.m_PositionSV = mul(g_JitteredProjection, float4(view_space_position, 1.));
+#ifndef PREPASS
+  result.m_Normal = mul(float4(vs_in.m_Normal, 0.), model_view).xyz;
+  result.m_Position = view_space_position;
   result.m_Tangent.xyz = mul(float4(vs_in.m_Tangent.xyz, 0.), model_view).xyz;
   result.m_Tangent.w = vs_in.m_Tangent.w;
-  result.m_PositionSV = mul(g_JitteredProjection, float4(result.m_Position, 1.));
   result.m_PositionCS = mul(g_Projection, float4(result.m_Position, 1.));
   float3 history_position = mul(float4(vs_in.m_Position, 1.), model_view_history);
   result.m_HistoryPositionCS = mul(g_ProjectionHistory, float4(history_position, 1.));
+#endif
   return result;
 }

betterRenderer/shaders/instanced_vertex.hlsl

@@ -8,6 +8,12 @@ struct VertexInput {
   float4 m_InstanceTransform[3] : InstanceTransform;
 };
 
+#ifdef PREPASS
+struct VertexOutput {
+  float2 m_TexCoord : TexCoord;
+  float4 m_PositionSV : SV_Position;
+};
+#else
 struct VertexOutput {
   float3 m_Position : Position;
   float3 m_Normal : Normal;
@@ -17,6 +23,7 @@ struct VertexOutput {
   float4 m_PositionCS : PositionCS;
   float4 m_HistoryPositionCS : HistoryPositionCS;
 };
+#endif
 
 cbuffer VertexConstants : register(b0) {
   float4x4 g_JitteredProjection;
@@ -32,14 +39,17 @@ VertexOutput main(in VertexInput vs_in) {
   float4x3 model_view_history = GetModelViewHistory();
   float4x4 instance_transform = transpose(float4x4(vs_in.m_InstanceTransform[0], vs_in.m_InstanceTransform[1], vs_in.m_InstanceTransform[2], float4(0., 0., 0., 1.)));
   float3 position = mul(float4(vs_in.m_Position, 1.), instance_transform).xyz;
-  result.m_Position = mul(float4(position, 1.), model_view).xyz;
-  result.m_Normal = mul(mul(float4(vs_in.m_Normal, 0.), instance_transform), model_view);
+  float3 view_space_position = mul(float4(position, 1.), model_view).xyz;
+  result.m_PositionSV = mul(g_JitteredProjection, float4(view_space_position, 1.));
   result.m_TexCoord = vs_in.m_TexCoord;
+#ifndef PREPASS
+  result.m_Position = view_space_position;
+  result.m_Normal = mul(mul(float4(vs_in.m_Normal, 0.), instance_transform), model_view);
   result.m_Tangent.xyz = mul(mul(float4(vs_in.m_Tangent.xyz, 0.), instance_transform), model_view);
   result.m_Tangent.w = vs_in.m_Tangent.w;
-  result.m_PositionSV = mul(g_JitteredProjection, float4(result.m_Position, 1.));
   result.m_PositionCS = mul(g_Projection, float4(result.m_Position, 1.));
   float3 history_position = mul(float4(position, 1.), model_view_history).xyz;
   result.m_HistoryPositionCS = mul(g_ProjectionHistory, float4(history_position, 1.));
+#endif
   return result;
 }

betterRenderer/shaders/manul/alpha_mask.hlsli

@@ -2,7 +2,9 @@
 #define ALPHA_MASK_HLSLI
 
 void AlphaMask(in float alpha) {
+#if (PASS & FORWARD_LIGHTING) || defined (SHADOW)
   if(g_DrawConstants.m_AlphaThreshold >= 0. ? (alpha < g_DrawConstants.m_AlphaThreshold) : (alpha >= -g_DrawConstants.m_AlphaThreshold)) discard;
+#endif
 }
 
 #endif

betterRenderer/shaders/project.manul

@@ -157,6 +157,12 @@ shaders:
       source: ps_shadow_masked
       target: pixel
       entrypoint: main
+    prepass_masked:
+      source: ps_shadow_masked
+      target: pixel
+      entrypoint: main
+      definitions:
+        PREPASS: 1
 # Contact shadows
 # TODO Depth conversion is broken since converting to reversed depth buffer
     contact_shadows:
@@ -173,6 +179,12 @@ shaders:
       source: default_vertex
       target: vertex
       entrypoint: main
+    default_prepass_vertex:
+      source: default_vertex
+      target: vertex
+      entrypoint: main
+      definitions:
+        PREPASS: 1
     shadow_vertex:
       source: shadow_vertex
       target: vertex
@@ -185,6 +197,12 @@ shaders:
       source: instanced_vertex
       target: vertex
       entrypoint: main
+    instanced_prepass_vertex:
+      source: instanced_vertex
+      target: vertex
+      entrypoint: main
+      definitions:
+        PREPASS: 1
     instanced_shadow_vertex:
       source: instanced_shadow_vertex
       target: vertex

betterRenderer/shaders/ps_shadow_masked.hlsl

@@ -3,8 +3,13 @@
 sampler diffuse_sampler : register(s0);
 Texture2D diffuse : register(t0);
 
+#ifdef PREPASS
+#include "manul/draw_constants.hlsli"
+#else
 #include "manul/draw_constants_shadow.hlsli"
+#endif
 
+#define SHADOW
 #include "manul/alpha_mask.hlsli"
 
 struct VertexOutput {