From ebee2513a9389e6e79baebcd8431e1a3495d58a6 Mon Sep 17 00:00:00 2001
From: Jannik Vogel <email@jannikvogel.de>
Date: Wed, 11 May 2016 13:39:56 +0200
Subject: [PATCH] Rasterizer: Implement fog
---
src/video_core/rasterizer.cpp | 73 +++++++++++++++++++++++++----------
1 file changed, 52 insertions(+), 21 deletions(-)
diff --git a/src/video_core/rasterizer.cpp b/src/video_core/rasterizer.cpp
index 65168f05ab..a84170094c 100644
--- a/src/video_core/rasterizer.cpp
+++ b/src/video_core/rasterizer.cpp
@@ -398,6 +398,26 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
float24::FromFloat32(static_cast<float>(w2)));
float24 interpolated_w_inverse = float24::FromFloat32(1.0f) / Math::Dot(w_inverse, baricentric_coordinates);
+ // interpolated_z = z / w
+ float interpolated_z_over_w = (v0.screenpos[2].ToFloat32() * w0 +
+ v1.screenpos[2].ToFloat32() * w1 +
+ v2.screenpos[2].ToFloat32() * w2) / wsum;
+
+ // Not fully accurate. About 3 bits in precision are missing.
+ // Z-Buffer (z / w * scale + offset)
+ float depth_scale = float24::FromRaw(regs.viewport_depth_range).ToFloat32();
+ float depth_offset = float24::FromRaw(regs.viewport_depth_near_plane).ToFloat32();
+ float depth = interpolated_z_over_w * depth_scale + depth_offset;
+
+ // Potentially switch to W-Buffer
+ if (regs.depthmap_enable == Pica::Regs::DepthBuffering::WBuffering) {
+ // W-Buffer (z * scale + w * offset = (z / w * scale + offset) * w)
+ depth *= interpolated_w_inverse.ToFloat32() * wsum;
+ }
+
+ // Clamp the result
+ depth = MathUtil::Clamp(depth, 0.0f, 1.0f);
+
// Perspective correct attribute interpolation:
// Attribute values cannot be calculated by simple linear interpolation since
// they are not linear in screen space. For example, when interpolating a
@@ -833,6 +853,38 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
continue;
}
+ // Apply fog combiner
+ // Not fully accurate. We'd have to know what data type is used to
+ // store the depth etc. Using float for now until we know more
+ // about Pica datatypes
+ if (regs.fog_mode == Regs::FogMode::Fog) {
+ const Math::Vec3<u8> fog_color = {
+ static_cast<u8>(regs.fog_color.r.Value()),
+ static_cast<u8>(regs.fog_color.g.Value()),
+ static_cast<u8>(regs.fog_color.b.Value()),
+ };
+
+ // Get index into fog LUT
+ float fog_index;
+ if (g_state.regs.fog_flip) {
+ fog_index = (1.0f - depth) * 128.0f;
+ } else {
+ fog_index = depth * 128.0f;
+ }
+
+ // Generate clamped fog factor from LUT for given fog index
+ float fog_i = MathUtil::Clamp(floorf(fog_index), 0.0f, 127.0f);
+ float fog_f = fog_index - fog_i;
+ const auto& fog_lut_entry = g_state.fog.lut[static_cast<unsigned int>(fog_i)];
+ float fog_factor = (fog_lut_entry.value + fog_lut_entry.difference * fog_f) / 2047.0f; // This is signed fixed point 1.11
+ fog_factor = MathUtil::Clamp(fog_factor, 0.0f, 1.0f);
+
+ // Blend the fog
+ for (unsigned i = 0; i < 3; i++) {
+ combiner_output[i] = fog_factor * combiner_output[i] + (1.0f - fog_factor) * fog_color[i];
+ }
+ }
+
u8 old_stencil = 0;
auto UpdateStencil = [stencil_test, x, y, &old_stencil](Pica::Regs::StencilAction action) {
@@ -887,27 +939,6 @@ static void ProcessTriangleInternal(const Shader::OutputVertex& v0,
}
}
- // interpolated_z = z / w
- float interpolated_z_over_w = (v0.screenpos[2].ToFloat32() * w0 +
- v1.screenpos[2].ToFloat32() * w1 +
- v2.screenpos[2].ToFloat32() * w2) / wsum;
-
- // Not fully accurate. About 3 bits in precision are missing.
- // Z-Buffer (z / w * scale + offset)
- float depth_scale = float24::FromRaw(regs.viewport_depth_range).ToFloat32();
- float depth_offset = float24::FromRaw(regs.viewport_depth_near_plane).ToFloat32();
- float depth = interpolated_z_over_w * depth_scale + depth_offset;
-
- // Potentially switch to W-Buffer
- if (regs.depthmap_enable == Pica::Regs::DepthBuffering::WBuffering) {
-
- // W-Buffer (z * scale + w * offset = (z / w * scale + offset) * w)
- depth *= interpolated_w_inverse.ToFloat32() * wsum;
- }
-
- // Clamp the result
- depth = MathUtil::Clamp(depth, 0.0f, 1.0f);
-
// Convert float to integer
unsigned num_bits = Regs::DepthBitsPerPixel(regs.framebuffer.depth_format);
u32 z = (u32)(depth * ((1 << num_bits) - 1));
--
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