commit ccdf7c495e787245e14b31873c024555741e7c0b
parent cb59b68ec96f35bae58e60379c51767150b3e65c
Author: Vincent Forest <vincent.forest@meso-star.com>
Date: Wed, 7 Oct 2015 09:39:22 +0200
Draft of the projective footprint sampling.
Build the transformation matrix from world space to footprint space with
respect to a sampled direction. Transform the Scene AABB in footprint
space to define the ray sampling domain. Finally ray-cast rays in
footprint space to generate an image of the geometry footprint.
Diffstat:
1 file changed, 152 insertions(+), 1 deletion(-)
diff --git a/src/salgae_estimator.c b/src/salgae_estimator.c
@@ -29,8 +29,12 @@
#include "salgae.h"
#include "salgae_device.h"
+#include <rsys/float2.h>
+#include <rsys/float3.h>
+#include <rsys/image.h>
#include <rsys/logger.h>
#include <rsys/mem_allocator.h>
+#include <rsys/stretchy_array.h>
#include <star/s3d.h>
#include <star/ssp.h>
@@ -48,6 +52,108 @@ struct salgae_estimator {
/*******************************************************************************
* Helper functions
******************************************************************************/
+static FINLINE uint16_t
+morton2D_decode(const uint32_t u32)
+{
+ uint32_t x = u32 & 0x55555555;
+ x = (x | (x >> 1)) & 0x33333333;
+ x = (x | (x >> 2)) & 0x0F0F0F0F;
+ x = (x | (x >> 4)) & 0x00FF00FF;
+ x = (x | (x >> 8)) & 0x0000FFFF;
+ return (uint16_t)x;
+}
+
+static FINLINE void
+build_transform(const float pos[3], const float basis[9], float transform[12])
+{
+ ASSERT(pos && basis && transform);
+
+ /* `transform' is the matrix from world to footprint space while basis is a
+ * 3x3 matrix from local to world space. The linear part of the transform
+ * matrix is thus the inverse of the `basis' matrix. Since basis encodes an
+ * orthonormal transformation, a simple transposition is sufficient to
+ * inverse it */
+ f3(transform + 0, basis[0], basis[3], basis[6]);
+ f3(transform + 3, basis[1], basis[4], basis[8]);
+ f3(transform + 6, basis[2], basis[5], basis[9]);
+ /* Affine part of the transform matrix */
+ transform[9] = -f3_dot(basis+0, pos);
+ transform[10] = -f3_dot(basis+3, pos);
+ transform[11] = -f3_dot(basis+6, pos);
+}
+
+static void
+trace_rays
+ (struct s3d_scene* scn,
+ const float basis[9],
+ const float pos[3],
+ const float lower[3], /* Transform space lower boundary of the RT volume */
+ const float upper[3], /* Transform space upper boundary of the RT volume */
+ const char* name)
+{
+
+#define DEFINITION 128
+ STATIC_ASSERT(IS_POW2(DEFINITION), Invalid_thumbnail_definition);
+
+ float axis_x[3], axis_y[3], axis_z[3];
+ float plane_size[2];
+ float pixel_size[2];
+ float ray_org[3];
+ float org[3];
+ float depth;
+ float range[2] = {0, FLT_MAX};
+ uint32_t npixels = (uint32_t)(DEFINITION * DEFINITION);
+ uint32_t ipixel;
+ uint16_t ipixel_x, ipixel_y;
+ unsigned char* img = NULL;
+ ASSERT(basis && pos && lower && upper);
+
+ img = sa_add(img, DEFINITION*DEFINITION);
+ ASSERT(img != NULL);
+
+ f2_sub(plane_size, upper, lower);
+ f3_mulf(axis_x, basis + 0, plane_size[0] * 0.5f);
+ f3_mulf(axis_y, basis + 3, plane_size[1] * 0.5f);
+ f3_set(axis_z, basis + 6);
+
+ depth = lower[2] + 1.e-6f; /* Ensure to be outside the RT volume */
+ f3_add(org, pos, f3_mulf(org, basis + 9, depth));
+
+ pixel_size[0] = 1.f / (float)DEFINITION;
+ pixel_size[1] = 1.f / (float)DEFINITION;
+
+ FOR_EACH(ipixel, 0, npixels) {
+ struct s3d_hit hit;
+ float sample[2], x[3], y[3];
+ size_t idst;
+
+ ipixel_x = morton2D_decode(ipixel);
+ ipixel_y = morton2D_decode(ipixel>>1);
+ sample[0] = ((float)ipixel_x + 0.5f) * pixel_size[0];
+ sample[1] = ((float)ipixel_y + 0.5f) * pixel_size[1];
+
+ f3_mulf(x, axis_x, sample[0]*2.f - 1.f);
+ f3_mulf(y, axis_y, sample[1]*2.f - 1.f);
+ f3_add(ray_org, f3_add(ray_org, x, y), org);
+
+ S3D(scene_trace_ray(scn, ray_org, axis_z, range, &hit));
+
+ idst = (size_t)(ipixel_y * DEFINITION + ipixel_x);
+ if(S3D_HIT_NONE(&hit)) {
+ img[idst] = 0;
+ } else {
+ float N[3], cosine;
+ f3_normalize(N, hit.normal);
+ if(0 > (cosine = f3_dot(N, axis_z))) {
+ cosine = f3_dot(f3_minus(N, N), axis_z);
+ }
+ img[idst] = (unsigned char)(cosine*255.f);
+ }
+ }
+ image_ppm_write(name, DEFINITION, DEFINITION, 1, img);
+ sa_release(img);
+}
+
static res_T
radiative_path_length
(struct salgae_device* dev,
@@ -86,9 +192,54 @@ radiative_path_length
S3D(scene_begin_session(scene, S3D_TRACE));
FOR_EACH(i, 0, NDIRS) {
+ char thumb_name[64];
float dir[4];
+ float centroid[3];
+ float basis[9];
+ float lower[3], upper[3];
+ float transform[16];
+ float pt[6][3];
+ int i;
+
ssp_ran_sphere_uniform(rng, dir);
- /* TODO */
+ S3D(scene_get_aabb(scene, lower, upper));
+
+ /* AABB vertex layout
+ * 6-------7
+ * /' /|
+ * 2-------3 |
+ * | 4.....|.5
+ * |, |/
+ * 0-------1 */
+ f3(pt[0], lower[0], lower[1], lower[2]);
+ f3(pt[1], upper[0], lower[1], lower[2]);
+ f3(pt[2], lower[0], upper[1], lower[2]);
+ f3(pt[3], upper[0], upper[1], lower[2]);
+ f3(pt[4], lower[0], lower[1], upper[2]);
+ f3(pt[5], upper[0], lower[1], upper[2]);
+ f3(pt[6], lower[0], upper[1], upper[2]);
+ f3(pt[7], upper[0], upper[1], upper[2]);
+
+ /* Build the transformation matrix from world to footprint space. Use the
+ * AABB centroid as the origin of the footprint space. */
+ f3_mulf(centroid, f3_add(centroid, lower, upper), 0.5f);
+ f33_basis(basis, dir);
+ build_transform(centroid, basis, transform);
+
+ /* Transform the AABB from world to footprint space */
+ FOR_EACH(i, 0, 6) {
+ f3_add(pt[i], f33_mulf3(pt[i], transform, pt[i]), transform + 9);
+ }
+
+ /* Compute the AABB of the footprint */
+ f3_splat(lower, FLT_MAX);
+ f3_splat(upper,-FLT_MAX);
+ FOR_EACH(i, 0, 6) {
+ f3_min(lower, lower, pt[i]);
+ f3_max(upper, upper, pt[i]);
+ }
+ sprintf(thumb_name, "thumb_%d.ppm", i);
+ trace_rays(scene, basis, centroid, lower, upper, thumb_name);
}
S3D(scene_end_session(scene));
