Revision: 22637
http://projects.blender.org/plugins/scmsvn/viewcvs.php?view=rev&root=bf-blender&revision=22637
Author: broken
Date: 2009-08-19 23:48:09 +0200 (Wed, 19 Aug 2009)
Log Message:
-----------
* volume rendering cleanups and optimisations
Modified Paths:
--------------
branches/volume25/source/blender/render/intern/source/volumetric.c
Modified: branches/volume25/source/blender/render/intern/source/volumetric.c
===================================================================
--- branches/volume25/source/blender/render/intern/source/volumetric.c
2009-08-19 21:47:47 UTC (rev 22636)
+++ branches/volume25/source/blender/render/intern/source/volumetric.c
2009-08-19 21:48:09 UTC (rev 22637)
@@ -237,6 +237,23 @@
/* Compute attenuation, otherwise known as 'optical thickness', extinction, or
tau.
* Used in the relationship Transmittance = e^(-attenuation)
*/
+void vol_get_attenuation_seg(ShadeInput *shi, float *tau, float *stepvec,
float *co, float density)
+{
+ /* input density = density at co */
+ float absorb_col[3];
+ const float dist = VecLength(stepvec);
+
+ vol_get_absorption(shi, absorb_col, co);
+
+ /* homogenous volume within the sampled distance */
+ tau[0] = tau[1] = tau[2] = dist * density;
+
+ VecMulVecf(tau, tau, absorb_col);
+}
+
+/* Compute attenuation, otherwise known as 'optical thickness', extinction, or
tau.
+ * Used in the relationship Transmittance = e^(-attenuation)
+ */
void vol_get_attenuation(ShadeInput *shi, float *tau, float *co, float *endco,
float density, float stepsize)
{
/* input density = density at co */
@@ -249,19 +266,8 @@
nsteps = (int)((dist / stepsize) + 0.5);
- /* trigger for recalculating density */
- if (density < -0.001f) density = vol_get_density(shi, co);
+ tau[0] = tau[1] = tau[2] = 0.0;
- if (nsteps == 1) {
- /* homogenous volume within the sampled distance */
- tau[0] = tau[1] = tau[2] = dist * density;
-
- VecMulVecf(tau, tau, absorb_col);
- return;
- } else {
- tau[0] = tau[1] = tau[2] = 0.0;
- }
-
VecSubf(step_vec, endco, co);
VecMulf(step_vec, 1.0f / nsteps);
@@ -402,22 +408,14 @@
static void volumeintegrate(struct ShadeInput *shi, float *col, float *co,
float *endco)
{
float tr[3] = {1.0f, 1.0f, 1.0f};
- float radiance[3] = {0.f, 0.f, 0.f}, d_radiance[3] = {0.f, 0.f, 0.f};
+ float radiance[3] = {0.f, 0.f, 0.f}, d_radiance[3] = {0.f, 0.f, 0.f},
radiance_behind[3];
float stepsize = vol_get_stepsize(shi, STEPSIZE_VIEW);
int nsteps, s;
float tau[3], emit_col[3], scatter_col[3] = {0.0, 0.0, 0.0};
float stepvec[3], step_sta[3], step_end[3], step_mid[3];
- float density = vol_get_density(shi, co);
+ float density;
const float depth_cutoff = shi->mat->vol.depth_cutoff;
-
- /* multiply col_behind with beam transmittance over entire distance */
- vol_get_attenuation(shi, tau, co, endco, density, stepsize);
- tr[0] *= exp(-tau[0]);
- tr[1] *= exp(-tau[1]);
- tr[2] *= exp(-tau[2]);
- VecMulVecf(radiance, tr, col);
- tr[0] = tr[1] = tr[2] = 1.0f;
-
+
/* ray marching */
nsteps = (int)((VecLenf(co, endco) / stepsize) + 0.5);
@@ -429,13 +427,13 @@
/* get radiance from all points along the ray due to participating
media */
for (s = 0; s < nsteps; s++) {
- if (s > 0) density = vol_get_density(shi, step_sta);
+ density = vol_get_density(shi, step_sta);
/* there's only any use in shading here if there's actually
some density to shade! */
if (density > 0.01f) {
/* transmittance component (alpha) */
- vol_get_attenuation(shi, tau, step_sta, step_end,
density, stepsize);
+ vol_get_attenuation_seg(shi, tau, stepvec, co, density);
tr[0] *= exp(-tau[0]);
tr[1] *= exp(-tau[1]);
tr[2] *= exp(-tau[2]);
@@ -469,6 +467,10 @@
if ((0.2126*tr[0] + 0.7152*tr[1] + 0.0722*tr[2]) <
depth_cutoff) break;
}
+ /* multiply original color (behind volume) with beam transmittance over
entire distance */
+ VecMulVecf(radiance_behind, tr, col);
+ VecAddf(radiance, radiance, radiance_behind);
+
VecCopyf(col, radiance);
col[3] = 1.0f -(tr[0] + tr[1] + tr[2]) * 0.333f;
}
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