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LibGL: Improve texture sampling performance

GL_NEAREST: Remove unnecessary modulo. UV is always in range due to
wrapping.
GL_LINEAR: Rewrite filter equation to save a few math operations.
This commit is contained in:
Stephan Unverwerth 2021-08-16 19:08:16 +02:00 committed by Andreas Kling
parent 59998ff0b2
commit 39ff1459f8

View file

@ -68,7 +68,7 @@ FloatVector4 Sampler2D::sample(FloatVector2 const& uv) const
// 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());
return mip.texel(static_cast<unsigned>(x), static_cast<unsigned>(y));
} else if (m_mag_filter == GL_LINEAR) {
// FIXME: Implement different sampling points for wrap modes other than GL_REPEAT
@ -88,8 +88,11 @@ FloatVector4 Sampler2D::sample(FloatVector2 const& uv) const
float frac_x = x - floorf(x);
float frac_y = y - floorf(y);
float one_minus_frac_x = 1 - frac_x;
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;
auto h1 = t0 * one_minus_frac_x + t1 * frac_x;
auto h2 = t2 * one_minus_frac_x + t3 * frac_x;
return h1 * (1 - frac_y) + h2 * frac_y;
} else {
VERIFY_NOT_REACHED();
}