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Add normal transforms and reconstruction.

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This commit is contained in:
castano 2011-02-28 09:05:28 +00:00
parent 609db2639e
commit 28592e73a8
2 changed files with 82 additions and 0 deletions
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75
src/nvtt/TexImage.cpp
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@ -1558,6 +1558,81 @@ void TexImage::normalizeNormalMap()
nv::normalizeNormalMap(m->image);
}
void TexImage::transformNormals(NormalTransform xform)
{
if (m->image == NULL) return;
detach();
const uint count = m->image->width() * m->image->height();
for (uint i = 0; i < count; i++) {
float & x = m->image->pixel(i, 0);
float & y = m->image->pixel(i, 1);
float & z = m->image->pixel(i, 2);
Vector3 n(x, y, z);
n = normalizeSafe(n, Vector3(0.0f), 0.0f);
if (xform == NormalTransform_Orthographic) {
n.z = 0.0f;
}
else if (xform == NormalTransform_Stereographic) {
n.x = n.x / (1 + n.z);
n.y = n.y / (1 + n.z);
n.z = 0.0f;
}
else if (xform == NormalTransform_Paraboloid) {
float a = (n.x * n.x) + (n.y * n.y);
float b = n.z;
float c = -1.0f;
float discriminant = b * b - 4.0f * a * c;
float t = (-b + sqrtf(discriminant)) / (2.0f * a);
n.x = n.x * t;
n.y = n.y * t;
n.z = 0.0f;
}
x = n.x;
y = n.y;
z = n.z;
}
}
void TexImage::reconstructNormals(NormalTransform xform)
{
if (m->image == NULL) return;
detach();
const uint count = m->image->width() * m->image->height();
for (uint i = 0; i < count; i++) {
float & x = m->image->pixel(i, 0);
float & y = m->image->pixel(i, 1);
float & z = m->image->pixel(i, 2);
Vector3 n(x, y, z);
if (xform == NormalTransform_Orthographic) {
n.z = sqrtf(n.x * n.x + n.y * n.y);
}
else if (xform == NormalTransform_Stereographic) {
float denom = 2.0f / (1 + n.x * n.x + n.y * n.y);
n.x *= denom;
n.y *= denom;
n.z = denom - 1;
}
else if (xform == NormalTransform_Paraboloid) {
n.x = n.x;
n.y = n.y;
n.z = 1.0f - nv::clamp(n.x * n.x + n.y * n.y, 0.0f, 1.0f);
n = normalizeSafe(n, Vector3(0.0f), 0.0f);
}
x = n.x;
y = n.y;
z = n.z;
}
}
void TexImage::flipVertically()
{
if (m->image == NULL) return;

7
src/nvtt/nvtt.h
View File

@ -387,6 +387,11 @@ namespace nvtt
// "Compressor" is deprecated. This should have been called "Context"
typedef Compressor Context;
enum NormalTransform {
NormalTransform_Orthographic,
NormalTransform_Stereographic,
NormalTransform_Paraboloid,
};
/// A texture mipmap.
struct TexImage
@ -465,6 +470,8 @@ namespace nvtt
// Normal map transforms.
NVTT_API void toNormalMap(float sm, float medium, float big, float large);
NVTT_API void normalizeNormalMap();
NVTT_API void transformNormals(NormalTransform xform);
NVTT_API void reconstructNormals(NormalTransform xform);
// Geometric transforms.
NVTT_API void flipVertically();