T55333 Workbench: Cavity Shader

A cavity shader based on SSAO. Works on all workbench deferred passes.

Per 3d viewport the cavity shader options can be set as different
shading needed different options. Some global options are in the
Viewport Display of the scene like num samples and distance.

Experimental: Naming of Ridges and Valleys

1 files changed, 58 insertions, 0 deletions

diff --git a/source/blender/draw/engines/workbench/workbench_data.c b/source/blender/draw/engines/workbench/workbench_data.c
index 7468d748986..3a4bb1db749 100644
--- a/source/blender/draw/engines/workbench/workbench_data.c
+++ b/source/blender/draw/engines/workbench/workbench_data.c
@@ -58,6 +58,64 @@ void workbench_private_data_init(WORKBENCH_PrivateData *wpd)
 	wd->object_outline_color[3] = 1.0f;
 
 	wpd->world_ubo = DRW_uniformbuffer_create(sizeof(WORKBENCH_UBO_World), &wpd->world_data);
+
+	/* Cavity settings */
+	{
+		const int ssao_samples = scene->display.matcap_ssao_samples;
+
+		float invproj[4][4];
+		float dfdyfacs[2];
+		const bool is_persp = DRW_viewport_is_persp_get();
+		/* view vectors for the corners of the view frustum.
+		 * Can be used to recreate the world space position easily */
+		float viewvecs[3][4] = {
+		    {-1.0f, -1.0f, -1.0f, 1.0f},
+		    {1.0f, -1.0f, -1.0f, 1.0f},
+		    {-1.0f, 1.0f, -1.0f, 1.0f}
+		};
+		int i;
+		const float *size = DRW_viewport_size_get();
+
+		DRW_state_dfdy_factors_get(dfdyfacs);
+
+		wpd->ssao_params[0] = ssao_samples;
+		wpd->ssao_params[1] = size[0] / 64.0;
+		wpd->ssao_params[2] = size[1] / 64.0;
+		wpd->ssao_params[3] = dfdyfacs[1]; /* dfdy sign for offscreen */
+
+		/* distance, factor, factor, attenuation */
+		copy_v4_fl4(wpd->ssao_settings, scene->display.matcap_ssao_distance, wpd->shading.cavity_valley_factor, wpd->shading.cavity_ridge_factor, scene->display.matcap_ssao_attenuation);
+
+		/* invert the view matrix */
+		DRW_viewport_matrix_get(wpd->winmat, DRW_MAT_WIN);
+		invert_m4_m4(invproj, wpd->winmat);
+
+		/* convert the view vectors to view space */
+		for (i = 0; i < 3; i++) {
+			mul_m4_v4(invproj, viewvecs[i]);
+			/* normalized trick see:
+			 * http://www.derschmale.com/2014/01/26/reconstructing-positions-from-the-depth-buffer */
+			mul_v3_fl(viewvecs[i], 1.0f / viewvecs[i][3]);
+			if (is_persp)
+				mul_v3_fl(viewvecs[i], 1.0f / viewvecs[i][2]);
+			viewvecs[i][3] = 1.0;
+
+			copy_v4_v4(wpd->viewvecs[i], viewvecs[i]);
+		}
+
+		/* we need to store the differences */
+		wpd->viewvecs[1][0] -= wpd->viewvecs[0][0];
+		wpd->viewvecs[1][1] = wpd->viewvecs[2][1] - wpd->viewvecs[0][1];
+
+		/* calculate a depth offset as well */
+		if (!is_persp) {
+			float vec_far[] = {-1.0f, -1.0f, 1.0f, 1.0f};
+			mul_m4_v4(invproj, vec_far);
+			mul_v3_fl(vec_far, 1.0f / vec_far[3]);
+			wpd->viewvecs[1][2] = vec_far[2] - wpd->viewvecs[0][2];
+		}
+	}
+
 }
 
 void workbench_private_data_get_light_direction(WORKBENCH_PrivateData *wpd, float light_direction[3])