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LibGL: Implement GL_LINEAR texture filter

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Stephan Unverwerth 2021-08-12 20:37:38 +02:00 committed by Andreas Kling
parent 00603d9fd0
commit 00d527bc25
Notes: sideshowbarker 2024-07-18 07:04:46 +09:00 
Author: https://github.com/sunverwerth
Commit: https://github.com/SerenityOS/serenity/commit/00d527bc258
Pull-request: https://github.com/SerenityOS/serenity/pull/9363
1 changed files with 50 additions and 43 deletions
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93
Userland/Libraries/LibGL/Tex/Sampler2D.cpp
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@ -29,6 +29,27 @@ static constexpr float wrap_clamp(float value)
return clamp(value, 0.0f, 1.0f);
}
static constexpr float wrap(float value, GLint mode)
{
switch (mode) {
case GL_REPEAT:
return wrap_repeat(value);
// FIXME: These clamp modes actually have slightly different behaviour
case GL_CLAMP:
case GL_CLAMP_TO_BORDER:
case GL_CLAMP_TO_EDGE:
return wrap_clamp(value);
case GL_MIRRORED_REPEAT:
return wrap_mirrored_repeat(value);
break;
default:
VERIFY_NOT_REACHED();
}
}
FloatVector4 Sampler2D::sample(FloatVector2 const& uv) const
{
// FIXME: Calculate the correct mipmap level here, need to receive uv derivatives for that
@ -36,53 +57,39 @@ FloatVector4 Sampler2D::sample(FloatVector2 const& uv) const
MipMap const& mip = m_texture.mipmap(lod);
float x = uv.x();
float y = uv.y();
switch (m_wrap_s_mode) {
case GL_REPEAT:
x = wrap_repeat(x);
break;
// FIXME: These clamp modes actually have slightly different behaviour
case GL_CLAMP:
case GL_CLAMP_TO_BORDER:
case GL_CLAMP_TO_EDGE:
x = wrap_clamp(x);
break;
case GL_MIRRORED_REPEAT:
x = wrap_mirrored_repeat(x);
break;
default:
VERIFY_NOT_REACHED();
}
switch (m_wrap_t_mode) {
case GL_REPEAT:
y = wrap_repeat(y);
break;
// FIXME: These clamp modes actually have slightly different behaviour
case GL_CLAMP:
case GL_CLAMP_TO_BORDER:
case GL_CLAMP_TO_EDGE:
y = wrap_clamp(y);
break;
case GL_MIRRORED_REPEAT:
y = wrap_mirrored_repeat(y);
break;
default:
VERIFY_NOT_REACHED();
}
float x = wrap(uv.x(), m_wrap_t_mode);
float y = wrap(uv.y(), m_wrap_s_mode);
x *= mip.width() - 1;
y *= mip.height() - 1;
return mip.texel(static_cast<unsigned>(x), static_cast<unsigned>(y));
// Sampling implemented according to https://www.khronos.org/registry/OpenGL/specs/gl/glspec121.pdf Chapter 3.8
if (m_mag_filter == GL_NEAREST) {
return mip.texel(static_cast<unsigned>(x) % mip.width(), static_cast<unsigned>(y) % mip.height());
} else if (m_mag_filter == GL_LINEAR) {
// FIXME: Implement different sampling points for wrap modes other than GL_REPEAT
x -= 0.5f;
y -= 0.5f;
unsigned i0 = static_cast<unsigned>(x) % mip.width();
unsigned j0 = static_cast<unsigned>(y) % mip.height();
unsigned i1 = (i0 + 1) % mip.width();
unsigned j1 = (j0 + 1) % mip.height();
auto t0 = mip.texel(i0, j0);
auto t1 = mip.texel(i1, j0);
auto t2 = mip.texel(i0, j1);
auto t3 = mip.texel(i1, j1);
float frac_x = x - floorf(x);
float frac_y = y - floorf(y);
return t0 * (1 - frac_x) * (1 - frac_y) + t1 * frac_x * (1 - frac_y) + t2 * (1 - frac_x) * frac_y + t3 * frac_x * frac_y;
} else {
VERIFY_NOT_REACHED();
}
}
}