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Rasterizer: Implement fog

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This commit is contained in:
Jannik Vogel 2016-05-11 13:39:56 +02:00
parent 57855a1701
commit ebee2513a9
1 changed files with 52 additions and 21 deletions
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73
src/video_core/rasterizer.cpp
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@ -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));