static void sample_data(texgz_tex_t* src,
texgz_tex_t* dst,
int x, int y,
int i, int j,
int m, int n,
double latT, double lonL,
double latB, double lonR)
{
assert(src);
assert(dst);
LOGD("debug x=%i, y=%i, i=%i, j=%i, m=%i, n=%i, latT=%lf, lonL=%lf, latB=%lf, lonR=%lf",
x, y, i, j, m, n, latT, lonL, latB, lonR);
// make a dummy tile
nedgz_tile_t* tile = nedgz_tile_new(x, y, 9);
if(tile == NULL)
{
return;
}
// compute sample coords
double lat;
double lon;
tile_coord(tile, i, j, m, n, &lat, &lon);
// compute u, v
float u = (float) ((lon - lonL)/(lonR - lonL));
float v = (float) ((lat - latT)/(latB - latT));
// interpolate color
unsigned char r;
unsigned char g;
unsigned char b;
interpolatec(src, u, v, &r, &g, &b);
// store color
unsigned char* pixels = dst->pixels;
int stride = dst->stride;
int bpp = texgz_tex_bpp(dst);
int idx = m*stride*bpp + n*bpp;
pixels[idx + 0] = r;
pixels[idx + 1] = g;
pixels[idx + 2] = b;
nedgz_tile_delete(&tile);
}
static void sample_data(texgz_tex_t* src,
texgz_tex_t* dst,
int x, int y,
int m, int n,
double latT, double lonL,
double latB, double lonR)
{
assert(src);
assert(dst);
// compute sample coords
double lat;
double lon;
float s = (float) (SUBTILE_SIZE - 1);
float xx = (float) x;
float yy = (float) y;
float nn = (float) n/s;
float mm = (float) m/s;
terrain_tile2coord(xx + nn, yy + mm, 9, &lat, &lon);
// compute u, v
float u = (float) ((lon - lonL)/(lonR - lonL));
float v = (float) ((lat - latT)/(latB - latT));
// interpolate color
unsigned char r;
unsigned char g;
unsigned char b;
interpolatec(src, u, v, &r, &g, &b);
// store color
unsigned char* pixels = dst->pixels;
int stride = dst->stride;
int bpp = texgz_tex_bpp(dst);
int idx = m*stride*bpp + n*bpp;
pixels[idx + 0] = r;
pixels[idx + 1] = g;
pixels[idx + 2] = b;
}
static void interpolatec(texgz_tex_t* tex,
float u, float v,
unsigned char* r,
unsigned char* g,
unsigned char* b)
{
assert(tex);
LOGD("debug u=%f, v=%f", u, v);
// "float indices"
float pu = u*(tex->width - 1);
float pv = v*(tex->height - 1);
// determine indices to sample
int u0 = (int) pu;
int v0 = (int) pv;
int u1 = u0 + 1;
int v1 = v0 + 1;
// double check the indices
if(u0 < 0)
{
u0 = 0;
}
if(u1 >= tex->width)
{
u1 = tex->width - 1;
}
if(v0 < 0)
{
v0 = 0;
}
if(v1 >= tex->height)
{
v1 = tex->height - 1;
}
// compute interpolation coordinates
float u0f = (float) u0;
float v0f = (float) v0;
float uf = pu - u0f;
float vf = pv - v0f;
// compute index
int bpp = texgz_tex_bpp(tex);
int stride = tex->stride;
int idx00 = v0*stride*bpp + u0*bpp;
int idx01 = v1*stride*bpp + u0*bpp;
int idx10 = v0*stride*bpp + u1*bpp;
int idx11 = v1*stride*bpp + u1*bpp;
// sample interpolation values
unsigned char* pixels = tex->pixels;
float r00 = (float) pixels[idx00];
float r01 = (float) pixels[idx01];
float r10 = (float) pixels[idx10];
float r11 = (float) pixels[idx11];
float g00 = (float) pixels[idx00 + 1];
float g01 = (float) pixels[idx01 + 1];
float g10 = (float) pixels[idx10 + 1];
float g11 = (float) pixels[idx11 + 1];
float b00 = (float) pixels[idx00 + 2];
float b01 = (float) pixels[idx01 + 2];
float b10 = (float) pixels[idx10 + 2];
float b11 = (float) pixels[idx11 + 2];
// interpolate u
float r0010 = r00 + uf*(r10 - r00);
float r0111 = r01 + uf*(r11 - r01);
float g0010 = g00 + uf*(g10 - g00);
float g0111 = g01 + uf*(g11 - g01);
float b0010 = b00 + uf*(b10 - b00);
float b0111 = b01 + uf*(b11 - b01);
// interpolate v
*r = (unsigned char) (r0010 + vf*(r0111 - r0010) + 0.5f);
*g = (unsigned char) (g0010 + vf*(g0111 - g0010) + 0.5f);
*b = (unsigned char) (b0010 + vf*(b0111 - b0010) + 0.5f);
}
static void naip_sampleEnd(texgz_tex_t* tex,
int zoom, int x, int y)
{
assert(tex);
// tex and node->tex are expected to have RGBA-8888
int i;
int j;
double lat;
double lon;
float xf = (float) x;
float yf = (float) y;
int bpp = texgz_tex_bpp(tex);
unsigned char pixel00[4];
unsigned char pixel01[4];
unsigned char pixel10[4];
unsigned char pixel11[4];
float pixelf[4];
for(i = 0; i < tex->height; ++i)
{
int offset = bpp*i*tex->stride;
for(j = 0; j < tex->width; ++j)
{
// compute pixel center
float ii = (float) i;
float jj = (float) j;
float xx = xf + jj/255.0f;
float yy = yf + ii/255.0f;
terrain_tile2coord(xx, yy, zoom,
&lat, &lon);
// find/cache the naip image
naip_node_t* node = naip_cache_findNode(lat, lon);
if(node == NULL)
{
offset += bpp;
continue;
}
// stochastic/random sampling pattern
float w = (float) node->tex->width;
float h = (float) node->tex->height;
float ssu0 = (0.5f + 0.25*stochastic())/w;
float ssu1 = (0.5f + 0.25*stochastic())/w;
float ssu2 = (0.5f + 0.25*stochastic())/w;
float ssu3 = (0.5f + 0.25*stochastic())/w;
float ssv0 = (0.5f + 0.25*stochastic())/h;
float ssv1 = (0.5f + 0.25*stochastic())/h;
float ssv2 = (0.5f + 0.25*stochastic())/h;
float ssv3 = (0.5f + 0.25*stochastic())/h;
// sample the pixel (MSAA)
double u0 = fabs(lon - node->l);
double v0 = fabs(lat - node->t);
double du = fabs(node->l - node->r);
double dv = fabs(node->t - node->b);
float u = (float) (u0/du);
float v = (float) (v0/dv);
texgz_tex_sample(node->tex, u - ssu0, v - ssv0,
bpp, pixel00);
texgz_tex_sample(node->tex, u + ssu1, v - ssv1,
bpp, pixel01);
texgz_tex_sample(node->tex, u - ssu2, v + ssv2,
bpp, pixel10);
texgz_tex_sample(node->tex, u + ssu3, v + ssv3,
bpp, pixel11);
// compute pixel average
pixelf[0] = ((float) pixel00[0] + (float) pixel01[0] +
(float) pixel10[0] + (float) pixel11[0])/4.0f;
pixelf[1] = ((float) pixel00[1] + (float) pixel01[1] +
(float) pixel10[1] + (float) pixel11[1])/4.0f;
pixelf[2] = ((float) pixel00[2] + (float) pixel01[2] +
(float) pixel10[2] + (float) pixel11[2])/4.0f;
pixelf[3] = ((float) pixel00[3] + (float) pixel01[3] +
(float) pixel10[3] + (float) pixel11[3])/4.0f;
// set the pixel
tex->pixels[offset + 0] = (unsigned char) pixelf[0];
tex->pixels[offset + 1] = (unsigned char) pixelf[1];
tex->pixels[offset + 2] = (unsigned char) pixelf[2];
tex->pixels[offset + 3] = (unsigned char) pixelf[3];
offset += bpp;
}
}
}