Implement shadow offsets for the new SM distortion function (#12191)

* Move shadow position calculation to vertex shaders
* Animate entire scene before rendering shadows to prevent lagging of shadows
* Remove unnecessary use of PolygonOffsetFactor
* Apply normal offset to both nodes and objects
* Rename getPerspectiveFactor -> applyPerspectiveDistortion
* Remove perspective distortion from fragment shaders

3 files changed, 12 insertions, 14 deletions

diff --git a/src/client/render/core.cpp b/src/client/render/core.cpp
index c67f297c4..55cc4e490 100644
--- a/src/client/render/core.cpp
+++ b/src/client/render/core.cpp
@@ -76,8 +76,11 @@ void RenderingCore::draw(video::SColor _skycolor, bool _show_hud, bool _show_min
 	draw_wield_tool = _draw_wield_tool;
 	draw_crosshair = _draw_crosshair;
 
-	if (shadow_renderer)
+	if (shadow_renderer) {
+		// This is necessary to render shadows for animations correctly
+		smgr->getRootSceneNode()->OnAnimate(device->getTimer()->getTime());
 		shadow_renderer->update();
+	}
 
 	beforeDraw();
 	drawAll();
diff --git a/src/client/shadows/dynamicshadows.h b/src/client/shadows/dynamicshadows.h
index 70574aa6c..6e9d96b15 100644
--- a/src/client/shadows/dynamicshadows.h
+++ b/src/client/shadows/dynamicshadows.h
@@ -69,12 +69,18 @@ public:
 	const core::matrix4 &getFutureProjectionMatrix() const;
 	core::matrix4 getViewProjMatrix();
 
-	/// Gets the light's far value.
+	/// Gets the light's maximum far value, i.e. the shadow boundary
 	f32 getMaxFarValue() const
 	{
 		return farPlane * BS;
 	}
 
+	/// Gets the current far value of the light
+	f32 getFarValue() const
+	{
+		return shadow_frustum.zFar;
+	}
+
 
 	/// Gets the light's color.
 	const video::SColorf &getLightColor() const
diff --git a/src/client/shadows/dynamicshadowsrender.cpp b/src/client/shadows/dynamicshadowsrender.cpp
index 1dfc90d1c..a008c3e06 100644
--- a/src/client/shadows/dynamicshadowsrender.cpp
+++ b/src/client/shadows/dynamicshadowsrender.cpp
@@ -143,7 +143,7 @@ size_t ShadowRenderer::getDirectionalLightCount() const
 f32 ShadowRenderer::getMaxShadowFar() const
 {
 	if (!m_light_list.empty()) {
-		float zMax = m_light_list[0].getMaxFarValue();
+		float zMax = m_light_list[0].getFarValue();
 		return zMax;
 	}
 	return 0.0f;
@@ -418,10 +418,6 @@ void ShadowRenderer::renderShadowMap(video::ITexture *target,
 
 		material.BackfaceCulling = false;
 		material.FrontfaceCulling = true;
-		material.PolygonOffsetFactor = 4.0f;
-		material.PolygonOffsetDirection = video::EPO_BACK;
-		//material.PolygonOffsetDepthBias = 1.0f/4.0f;
-		//material.PolygonOffsetSlopeScale = -1.f;
 
 		if (m_shadow_map_colored && pass != scene::ESNRP_SOLID) {
 			material.MaterialType = (video::E_MATERIAL_TYPE) depth_shader_trans;
@@ -431,9 +427,6 @@ void ShadowRenderer::renderShadowMap(video::ITexture *target,
 			material.BlendOperation = video::EBO_MIN;
 		}
 
-		// FIXME: I don't think this is needed here
-		map_node->OnAnimate(m_device->getTimer()->getTime());
-
 		m_driver->setTransform(video::ETS_WORLD,
 				map_node->getAbsoluteTransformation());
 
@@ -479,10 +472,6 @@ void ShadowRenderer::renderShadowObjects(
 
 			current_mat.BackfaceCulling = true;
 			current_mat.FrontfaceCulling = false;
-			current_mat.PolygonOffsetFactor = 1.0f/2048.0f;
-			current_mat.PolygonOffsetDirection = video::EPO_BACK;
-			//current_mat.PolygonOffsetDepthBias = 1.0 * 2.8e-6;
-			//current_mat.PolygonOffsetSlopeScale = -1.f;
 		}
 
 		m_driver->setTransform(video::ETS_WORLD,