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LibSoftGPU: Use eye coordinates for fog calculation

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Now that we calculate and store eye coordinates for each vertex, we
should use their `z` values for the fragment depth used in further fog
calculations.

This fixes the fog in Tux Racer :^)
This commit is contained in:
Jelle Raaijmakers 2021-12-30 00:53:43 +01:00 • committed by Andreas Kling
parent fef7f7159c
commit 69da279073
1 changed files with 15 additions and 7 deletions
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22
Userland/Libraries/LibSoftGPU/Device.cpp
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@ -216,6 +216,11 @@ static void rasterize_triangle(const RasterizerOptions& options, Gfx::Bitmap& re
FloatVector4 pixel_staging[RASTERIZER_BLOCK_SIZE][RASTERIZER_BLOCK_SIZE];
float depth_staging[RASTERIZER_BLOCK_SIZE][RASTERIZER_BLOCK_SIZE];
// Fog depths
float const vertex0_eye_absz = fabs(vertex0.eye_coordinates.z());
float const vertex1_eye_absz = fabs(vertex1.eye_coordinates.z());
float const vertex2_eye_absz = fabs(vertex2.eye_coordinates.z());
// FIXME: implement stencil testing
// Iterate over all blocks within the bounds of the triangle
@ -390,10 +395,13 @@ static void rasterize_triangle(const RasterizerOptions& options, Gfx::Bitmap& re
auto uv = interpolate(vertex0.tex_coord, vertex1.tex_coord, vertex2.tex_coord, barycentric);
// Calculate depth of fragment for fog
float z = interpolate(triangle.vertices[0].position.z(), triangle.vertices[1].position.z(), triangle.vertices[2].position.z(), barycentric);
z = options.depth_min + (options.depth_max - options.depth_min) * (z + 1) / 2;
//
// OpenGL 1.5 spec chapter 3.10: "An implementation may choose to approximate the
// eye-coordinate distance from the eye to each fragment center by |Ze|."
*pixel = pixel_shader(uv, vertex_color, z);
float fog_fragment_depth = interpolate(vertex0_eye_absz, vertex1_eye_absz, vertex2_eye_absz, barycentric);
*pixel = pixel_shader(uv, vertex_color, fog_fragment_depth);
}
}
@ -707,7 +715,7 @@ void Device::draw_primitives(PrimitiveType primitive_type, FloatMatrix4x4 const&
void Device::submit_triangle(const Triangle& triangle, Vector<size_t> const& enabled_texture_units)
{
rasterize_triangle(m_options, *m_render_target, *m_depth_buffer, triangle, [this, &enabled_texture_units](FloatVector4 const& uv, FloatVector4 const& color, float z) -> FloatVector4 {
rasterize_triangle(m_options, *m_render_target, *m_depth_buffer, triangle, [this, &enabled_texture_units](FloatVector4 const& uv, FloatVector4 const& color, float fog_depth) -> FloatVector4 {
FloatVector4 fragment = color;
for (size_t i : enabled_texture_units) {
@ -743,13 +751,13 @@ void Device::submit_triangle(const Triangle& triangle, Vector<size_t> const& ena
float factor = 0.0f;
switch (m_options.fog_mode) {
case FogMode::Linear:
factor = (m_options.fog_end - z) / (m_options.fog_end - m_options.fog_start);
factor = (m_options.fog_end - fog_depth) / (m_options.fog_end - m_options.fog_start);
break;
case FogMode::Exp:
factor = exp(-((m_options.fog_density * z)));
factor = expf(-m_options.fog_density * fog_depth);
break;
case FogMode::Exp2:
factor = exp(-((m_options.fog_density * z) * (m_options.fog_density * z)));
factor = expf(-((m_options.fog_density * fog_depth) * (m_options.fog_density * fog_depth)));
break;
default:
VERIFY_NOT_REACHED();