コード例 #1
0
ファイル: volumetric.c プロジェクト: OldBrunet/BGERTPS
/* For ease of use, I've also introduced a 'reflection' and 'reflection color' parameter, which isn't 
 * physically correct. This works as an RGB tint/gain on out-scattered light, but doesn't affect the light 
 * that is transmitted through the volume. While having wavelength dependent absorption/scattering is more correct,
 * it also makes it harder to control the overall look of the volume since coloring the outscattered light results
 * in the inverse color being transmitted through the rest of the volume.
 */
static void volumeintegrate(struct ShadeInput *shi, float *col, float *co, float *endco)
{
	float radiance[3] = {0.f, 0.f, 0.f};
	float tr[3] = {1.f, 1.f, 1.f};
	float p[3] = {co[0], co[1], co[2]};
	float step_vec[3] = {endco[0] - co[0], endco[1] - co[1], endco[2] - co[2]};
	const float stepsize = shi->mat->vol.stepsize;
	
	float t0 = 0.f;
	float pt0 = t0;
	float t1 = normalize_v3(step_vec);	/* returns vector length */
	
	t0 += stepsize * ((shi->mat->vol.stepsize_type == MA_VOL_STEP_CONSTANT) ? 0.5f : BLI_thread_frand(shi->thread));
	p[0] += t0 * step_vec[0];
	p[1] += t0 * step_vec[1];
	p[2] += t0 * step_vec[2];
	mul_v3_fl(step_vec, stepsize);
	
	for (; t0 < t1; pt0 = t0, t0 += stepsize) {
		const float density = vol_get_density(shi, p);
		
		if (density > 0.00001f) {
			float scatter_col[3] = {0.f, 0.f, 0.f}, emit_col[3];
			const float stepd = (t0 - pt0) * density;
			
			/* transmittance component (alpha) */
			vol_get_transmittance_seg(shi, tr, stepsize, co, density);
			
			if (t0 > t1 * 0.25f) {
				/* only use depth cutoff after we've traced a little way into the volume */
				if (luminance(tr) < shi->mat->vol.depth_cutoff) break;
			}
			
			vol_get_emission(shi, emit_col, p);
			
			if (shi->obi->volume_precache) {
				float p2[3];
				
				p2[0] = p[0] + (step_vec[0] * 0.5f);
				p2[1] = p[1] + (step_vec[1] * 0.5f);
				p2[2] = p[2] + (step_vec[2] * 0.5f);
				
				vol_get_precached_scattering(&R, shi, scatter_col, p2);
			} else
				vol_get_scattering(shi, scatter_col, p);
			
			radiance[0] += stepd * tr[0] * (emit_col[0] + scatter_col[0]);
			radiance[1] += stepd * tr[1] * (emit_col[1] + scatter_col[1]);
			radiance[2] += stepd * tr[2] * (emit_col[2] + scatter_col[2]);
		}
		add_v3_v3(p, step_vec);
	}
	
	/* multiply original color (from behind volume) with transmittance over entire distance */
	mul_v3_v3v3(col, tr, col);
	add_v3_v3(col, radiance);
	
	/* alpha <-- transmission luminance */
	col[3] = 1.0f - luminance(tr);
}
コード例 #2
0
ファイル: volumetric.c プロジェクト: danielmarg/blender-main
/* Compute transmittance = e^(-attenuation) */
static void vol_get_transmittance(ShadeInput *shi, float tr[3], const float co[3], const float endco[3])
{
	float p[3] = {co[0], co[1], co[2]};
	float step_vec[3] = {endco[0] - co[0], endco[1] - co[1], endco[2] - co[2]};
	float tau[3] = {0.f, 0.f, 0.f};

	float t0 = 0.f;
	float t1 = normalize_v3(step_vec);
	float pt0 = t0;
	
	t0 += shi->mat->vol.stepsize * ((shi->mat->vol.stepsize_type == MA_VOL_STEP_CONSTANT) ? 0.5f : BLI_thread_frand(shi->thread));
	p[0] += t0 * step_vec[0];
	p[1] += t0 * step_vec[1];
	p[2] += t0 * step_vec[2];
	mul_v3_fl(step_vec, shi->mat->vol.stepsize);

	for (; t0 < t1; pt0 = t0, t0 += shi->mat->vol.stepsize) {
		const float d = vol_get_density(shi, p);
		const float stepd = (t0 - pt0) * d;
		float sigma_t[3];
		
		vol_get_sigma_t(shi, sigma_t, p);
		
		tau[0] += stepd * sigma_t[0];
		tau[1] += stepd * sigma_t[1];
		tau[2] += stepd * sigma_t[2];
		
		add_v3_v3(p, step_vec);
	}
	
	/* return transmittance */
	tr[0] = expf(-tau[0]);
	tr[1] = expf(-tau[1]);
	tr[2] = expf(-tau[2]);
}