Spectrum MIPMap::getValue(Float u, Float v,
Float dudx, Float dudy, Float dvdx, Float dvdy) const {
if (m_filterType == ETrilinear) {
++mipmapLookups;
/* Conservatively estimate a square lookup region */
Float width = 2.0f * std::max(
std::max(std::abs(dudx), std::abs(dudy)),
std::max(std::abs(dvdx), std::abs(dvdy)));
Float mipmapLevel = m_levels - 1 +
log2(std::max(width, (Float) 1e-8f));
if (mipmapLevel < 0) {
/* The lookup is smaller than one pixel */
return triangle(0, u, v);
} else if (mipmapLevel >= m_levels - 1) {
/* The lookup is larger than the whole texture */
return getTexel(m_levels - 1, 0, 0);
} else {
/* Tri-linear interpolation */
int level = (int) mipmapLevel;
Float delta = mipmapLevel - level;
return triangle(level, u, v) * (1.0f - delta)
+ triangle(level, u, v) * delta;
}
} else if (m_filterType == EEWA) {
if (dudx*dudx + dudy*dudy < dvdx*dvdx + dvdy*dvdy) {
std::swap(dudx, dvdx);
std::swap(dudy, dvdy);
}
Float majorLength = std::sqrt(dudx * dudx + dudy * dudy);
Float minorLength = std::sqrt(dvdx * dvdx + dvdy * dvdy);
if (minorLength * m_maxAnisotropy < majorLength && minorLength > 0.0f) {
Float scale = majorLength / (minorLength * m_maxAnisotropy);
dvdx *= scale; dvdy *= scale;
minorLength *= scale;
}
if (minorLength == 0)
return triangle(0, u, v);
// The min() below avoids overflow in the int conversion when lod=inf
Float lod =
std::min(std::max((Float) 0, m_levels - 1 + log2(minorLength)),
(Float) (m_levels-1));
int ilod = floorToInt(lod);
Float d = lod - ilod;
return EWA(u, v, dudx, dudy, dvdx, dvdy, ilod) * (1-d) +
EWA(u, v, dudx, dudy, dvdx, dvdy, ilod+1) * d;
} else {
int xPos = floorToInt(u*m_levelWidth[0]),
yPos = floorToInt(v*m_levelHeight[0]);
return getTexel(0, xPos, yPos);
}
}
Spectrum MIPMap::triangle(int level, Float x, Float y) const {
if (m_filterType == ENone) {
int xPos = floorToInt(x*m_levelWidth[0]),
yPos = floorToInt(y*m_levelHeight[0]);
return getTexel(0, xPos, yPos);
} else {
level = clamp(level, 0, m_levels - 1);
x = x * m_levelWidth[level] - 0.5f;
y = y * m_levelHeight[level] - 0.5f;
int xPos = floorToInt(x), yPos = floorToInt(y);
Float dx = x - xPos, dy = y - yPos;
return getTexel(level, xPos, yPos) * (1.0f - dx) * (1.0f - dy)
+ getTexel(level, xPos, yPos + 1) * (1.0f - dx) * dy
+ getTexel(level, xPos + 1, yPos) * dx * (1.0f - dy)
+ getTexel(level, xPos + 1, yPos + 1) * dx * dy;
}
}
Spectrum MIPMap::EWA(Float u, Float v, Float dudx, Float dudy, Float dvdx,
Float dvdy, int level) const {
++ewaLookups;
if (level >= m_levels)
return getTexel(m_levels-1, 0, 0);
Spectrum result(0.0f);
Float denominator = 0.0f;
u = u * m_levelWidth[level]; v = v * m_levelHeight[level];
dudx = dudx * m_levelWidth[level]; dudy = dudy * m_levelHeight[level];
dvdx = dvdx * m_levelWidth[level]; dvdy = dvdy * m_levelHeight[level];
Float A = dudy * dudy + dvdy * dvdy + 1.0f;
Float B = -2.0f * (dudx * dudy + dvdx * dvdy);
Float C = dudx * dudx + dvdx * dvdx + 1.0f;
Float F = A * C - B * B * 0.25f;
Float du = std::sqrt(C), dv = std::sqrt(A);
int u0 = (int) std::ceil(u - du);
int u1 = (int) std::floor(u + du);
int v0 = (int) std::ceil(v - dv);
int v1 = (int) std::floor(v + dv);
Float invF = 1.0f / F;
A *= invF; B *= invF; C *= invF;
for (int ut = u0; ut <= u1; ++ut) {
const Float uu = ut - u;
for (int vt = v0; vt <= v1; ++vt) {
const Float vv = vt - v;
const Float r2 = A*uu*uu + B*uu*vv + C*vv*vv;
if (r2 < 1) {
const Float weight = m_weightLut[
std::max(0, std::min((int) (r2 * MIPMAP_LUTSIZE), MIPMAP_LUTSIZE - 1))];
result += getTexel(level, ut, vt) * weight;
denominator += weight;
}
}
}
return result / denominator;
}
/**
* Returns an interpolated texel using bi-linear texture filtering
*/
static glm::vec3 readTexture(texture& tex, float s, float t) {
float xf = std::min(s*tex.width, tex.width-1.0f);
float yf = std::min(t*tex.height, tex.height-1.0f);
//// Find the diffrent texture coords.
float xMin = glm::floor(xf);
float yMin = glm::floor(yf);
float xMax = glm::ceil(xf);
float yMax = glm::ceil(yf);
////// Find the four nearest texels.
glm::vec3 A = getTexel(tex, xMin, yMin);
glm::vec3 B = getTexel(tex, xMax, yMin);
glm::vec3 C = getTexel(tex, xMax, yMax);
glm::vec3 D = getTexel(tex, xMin, yMax);
glm::vec3 xTop;
glm::vec3 xBot;
float divx = xMax - xMin;
float divy = yMax - yMin;
//horizontal interpolation
if (divx > 0.0f) {
xTop = ((xMax-xf)/divx)*A + ((xf-xMin)/divx)*B;
xBot = ((xMax-xf)/divx)*D + ((xf-xMin)/divx)*C;
}
else {
xTop = 1.0f*A + 0.0f*B;
xBot = 1.0f*D + 0.0f*C;
}
//vertical interpolation
if (divy > 0.0f) {
return ((yMax-yf)/divy)*xTop + ((yf-yMin)/divy)*xBot;
}
return 1.0f * xTop + 0.0f * xBot;
}
/* Isotropic/anisotropic EWA mip-map texture map class based on PBRT */
MIPMap::MIPMap(int width, int height, Spectrum *pixels,
EFilterType filterType, EWrapMode wrapMode, Float maxAnisotropy)
: m_width(width), m_height(height), m_filterType(filterType),
m_wrapMode(wrapMode), m_maxAnisotropy(maxAnisotropy) {
Spectrum *texture = pixels;
if (filterType != ENone && (!isPow2(width) || !isPow2(height))) {
m_width = (int) roundToPow2((uint32_t) width);
m_height = (int) roundToPow2((uint32_t) height);
/* The texture needs to be up-sampled */
Spectrum *texture1 = new Spectrum[m_width*height];
/* Re-sample into the X direction */
ResampleWeight *weights = resampleWeights(width, m_width);
for (int y=0; y<height; y++) {
for (int x=0; x<m_width; x++) {
texture1[x+m_width*y] = Spectrum(0.0f);
for (int j=0; j<4; j++) {
int pos = weights[x].firstTexel + j;
if (pos < 0 || pos >= height) {
if (wrapMode == ERepeat)
pos = modulo(pos, width);
else if (wrapMode == EClamp)
pos = clamp(pos, 0, width-1);
}
if (pos >= 0 && pos < width)
texture1[x+m_width*y] += pixels[pos+y*width]
* weights[x].weight[j];
}
}
}
delete[] weights;
delete[] pixels;
/* Re-sample into the Y direction */
texture = new Spectrum[m_width*m_height];
weights = resampleWeights(height, m_height);
memset(texture, 0, sizeof(Spectrum)*m_width*m_height);
for (int x=0; x<m_width; x++) {
for (int y=0; y<m_height; y++) {
for (int j=0; j<4; j++) {
int pos = weights[y].firstTexel + j;
if (pos < 0 || pos >= height) {
if (wrapMode == ERepeat)
pos = modulo(pos, height);
else if (wrapMode == EClamp)
pos = clamp(pos, 0, height-1);
}
if (pos >= 0 && pos < height)
texture[x+m_width*y] += texture1[x+pos*m_width]
* weights[y].weight[j];
}
}
}
for (int y=0; y<m_height; y++)
for (int x=0; x<m_width; x++)
texture[x+m_width*y].clampNegative();
delete[] weights;
delete[] texture1;
}
if (m_filterType != ENone)
m_levels = 1 + log2i((uint32_t) std::max(width, height));
else
m_levels = 1;
m_pyramid = new Spectrum*[m_levels];
m_pyramid[0] = texture;
m_levelWidth = new int[m_levels];
m_levelHeight= new int[m_levels];
m_levelWidth[0] = m_width;
m_levelHeight[0] = m_height;
/* Generate the mip-map hierarchy */
for (int i=1; i<m_levels; i++) {
m_levelWidth[i] = std::max(1, m_levelWidth[i-1]/2);
m_levelHeight[i] = std::max(1, m_levelHeight[i-1]/2);
m_pyramid[i] = new Spectrum[m_levelWidth[i] * m_levelHeight[i]];
for (int y = 0; y < m_levelHeight[i]; y++) {
for (int x = 0; x < m_levelWidth[i]; x++) {
m_pyramid[i][x+y*m_levelWidth[i]] = (
getTexel(i-1, 2*x, 2*y) +
getTexel(i-1, 2*x+1, 2*y) +
getTexel(i-1, 2*x, 2*y+1) +
getTexel(i-1, 2*x+1, 2*y+1)) * 0.25f;
}
}
}
if (m_filterType == EEWA) {
m_weightLut = static_cast<Float *>(allocAligned(sizeof(Float)*MIPMAP_LUTSIZE));
for (int i=0; i<MIPMAP_LUTSIZE; ++i) {
Float pos = (Float) i / (Float) (MIPMAP_LUTSIZE-1);
m_weightLut[i] = std::exp(-2.0f * pos) - std::exp(-2.0f);
}
}
}
Color lambertian(Ray normal, const Scene* s, Sphere* sphere, Plane* plane)
{
Color result;
result.r = 0;
result.g = 0;
result.b = 0;
bool blocked;
for(int i = 0; i < s->lights.size(); i++)
{
blocked = false;
Light current_light = s->lights.at(i);
Ray lightRay;
lightRay.p0 = current_light.origin;
lightRay.dir = sub(normal.p0, current_light.origin);
lightRay.dir = normalize(lightRay.dir);
// check that point of interest is not shadowed by other objects
float distFromLight = dist(normal.p0, current_light.origin);
float distClosestObject = fInfinity; // distance between light and closest object along ray to normal initial point
for(int k = 0; k < s->planes.size(); k++)
{
Plane current_plane = s->planes.at(k);
if(!areEqual(¤t_plane, plane))
{
distClosestObject = plane_intersect(¤t_plane, &lightRay);
// check if current object would block the light
if(distClosestObject < distFromLight)
{
blocked = true;
break;
}
}
}
for(int k = 0; k < s->spheres.size(); k++)
{
Sphere current_sphere = s->spheres.at(k);
if(!areEqual(¤t_sphere, sphere))
{
distClosestObject = sphere_intersect(¤t_sphere, &lightRay);
// check if current object would block the light
if(distClosestObject < distFromLight)
{
blocked = true;
break;
}
}
}
// check that the light source isn't behind the object
Vec3 lv = lightRay.dir;
Vec3 nv = normalize(normal.dir);
if(dot(lv, nv) > 0.0)
blocked = true;
if(!blocked)
{
// add this light's contribution to the pixel color
float coef = abs(dot(lv, nv));
if(sphere != NULL)
{
result.r += (sphere->material.color.r * current_light.color.r) * coef;
result.g += (sphere->material.color.g * current_light.color.g) * coef;
result.b += (sphere->material.color.b * current_light.color.b) * coef;
}
else if(plane != NULL)
{
if(plane->hastexture)
{
Color textureColor = getTextureColor(getTexel(normal,plane),plane);
result.r += textureColor.r * current_light.color.r * coef;
result.g += textureColor.g * current_light.color.g * coef;
result.b += textureColor.b * current_light.color.b * coef;
}
else
{
result.r += (plane->material.color.r * current_light.color.r) * coef;
result.g += (plane->material.color.g * current_light.color.g) * coef;
result.b += (plane->material.color.b * current_light.color.b) * coef;
}
}
}
}
return result;
}
/*
* @brief integrateTexture Get a texel by computing the mean of the color on a neighborood of size (deltas x deltat)
* @param pixels The image to access, organized as a linear array of texel arranged by row
* @param width Width of the image
* @param height Height of the image
* @param depth Depth of the image (number of component by texel)
* @param s The column coordinate of the requested texel as a floating point
* @param t The row coordinate of the requested texel as a floating point
* @param deltas The size, in the column dimension, of the neighborood
* @param deltat The size, in the row dimension, of the neighborood
* @return
* @todo
*/
Color integrateTexture(unsigned char *pixels, int width, int height, int depth, float s, float t, int deltas, int deltat){
return getTexel(pixels, width, height, depth, (int)std::floor(s), (int)std::floor(t));
}