From 82282de52e8e8f3bbafefaf92bf76f53f2c2495e Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Thu, 29 Apr 2021 00:18:54 +0300
Subject: [PATCH] Move lighting calculations to world space

Eye space lighting was a holdover from legacy OpenGL.  TBN space lighting
was similarly a kludge from old dot3 bump mapping.  Using world space
makes everything a lot simpler and allows some additional optimizations.
---
 builtin_data/_occluder.glsl       |  2 +-
 builtin_data/_sky_backdrop.glsl   |  2 +-
 shaderlib/common.glsl             | 47 ++++++++++++++-----------------
 shaderlib/cooktorrance.glsl       | 20 ++-----------
 shaderlib/msp_interface.glsl      |  8 +++---
 shaderlib/phong.glsl              | 20 ++-----------
 shaderlib/shadow.glsl             |  6 ++--
 source/effects/environmentmap.cpp |  5 ++--
 source/effects/environmentmap.h   |  2 +-
 source/effects/shadowmap.cpp      | 10 ++-----
 source/effects/shadowmap.h        |  2 +-
 source/materials/lighting.cpp     |  5 +---
 source/render/renderer.cpp        | 39 +++++++++++--------------
 source/render/renderer.h          | 15 ++++------
 source/render/scene.cpp           |  2 +-
 15 files changed, 68 insertions(+), 117 deletions(-)

diff --git a/builtin_data/_occluder.glsl b/builtin_data/_occluder.glsl
index e46ca02b..488d4120 100644
--- a/builtin_data/_occluder.glsl
+++ b/builtin_data/_occluder.glsl
@@ -2,7 +2,7 @@ import msp_interface;
 #pragma MSP stage(vertex)
 void main()
 {
-	gl_Position = projection_matrix*eye_obj_matrix*vertex;
+	gl_Position = clip_eye_matrix*eye_world_matrix*world_obj_matrix*vertex;
 }
 #pragma MSP stage(fragment)
 void main()
diff --git a/builtin_data/_sky_backdrop.glsl b/builtin_data/_sky_backdrop.glsl
index 0aac6c80..8d9f4ab9 100644
--- a/builtin_data/_sky_backdrop.glsl
+++ b/builtin_data/_sky_backdrop.glsl
@@ -7,7 +7,7 @@ uniform sampler2D distant;
 void main()
 {
 	gl_Position = vec4(vertex.xy, 1.0, 1.0);
-	mat4 inv_projection = inverse(projection_matrix);
+	mat4 inv_projection = inverse(clip_eye_matrix);
 	out vec4 view_dir = inv_projection*vec4(vertex.xy, -1.0, 1.0);
 	view_dir /= view_dir.w;
 	view_dir = inverse(eye_world_matrix)*vec4(view_dir.xyz, 0.0);
diff --git a/shaderlib/common.glsl b/shaderlib/common.glsl
index 8bc652fc..94237c7a 100644
--- a/shaderlib/common.glsl
+++ b/shaderlib/common.glsl
@@ -3,7 +3,7 @@ import shadow;
 
 uniform EnvMap
 {
-	mat3 env_eye_matrix;
+	mat3 env_world_matrix;
 };
 
 uniform sampler2D normal_map;
@@ -24,12 +24,12 @@ virtual vec3 get_vertex_normal()
 
 virtual mat4 get_vertex_transform()
 {
-	return eye_obj_matrix;
+	return world_obj_matrix;
 }
 
 virtual mat3 get_normal_transform()
 {
-	return eye_obj_normal_matrix;
+	return world_obj_normal_matrix;
 }
 
 void standard_transform()
@@ -37,33 +37,31 @@ void standard_transform()
 	mat4 vertex_tf = get_vertex_transform();
 	mat3 normal_tf = get_normal_transform();
 
-	out vec4 eye_vertex = vertex_tf*get_vertex_position();
-	gl_Position = projection_matrix*eye_vertex;
+	vec4 world_vertex = vertex_tf*get_vertex_position();
+	vec4 eye_vertex = eye_world_matrix*world_vertex;
+	gl_Position = clip_eye_matrix*eye_vertex;
 
-	out vec3 eye_normal = normal_tf*get_vertex_normal();
-	vec3 eye_tangent = normal_tf*tangent;
-	vec3 eye_binormal = cross(eye_normal, eye_tangent);
-	out mat3 eye_tbn_matrix = mat3(eye_tangent, eye_binormal, eye_normal);
+	out vec3 world_normal = normal_tf*get_vertex_normal();
+	vec3 world_tangent = normal_tf*tangent;
+	vec3 world_binormal = cross(world_normal, world_tangent);
+	out mat3 world_tbn_matrix = mat3(world_tangent, world_binormal, world_normal);
 
-	out vec3 eye_look_dir = normalize(eye_vertex.xyz);
-	out vec3 tbn_look_dir = eye_look_dir*eye_tbn_matrix;
+	vec3 eye_pos = (inverse(eye_world_matrix)*vec4(0.0, 0.0, 0.0, 1.0)).xyz;
+	out vec3 world_look_dir = normalize(world_vertex.xyz-eye_pos);
 
-	out vec3 eye_light_dir = normalize(light_sources[0].position.xyz-eye_vertex.xyz*light_sources[0].position.w);
-	out vec3 tbn_light_dir = eye_light_dir*eye_tbn_matrix;
+	out vec3 world_light_dir = light_sources[0].position.xyz-world_vertex.xyz*light_sources[0].position.w;
 
-	out vec3 eye_halfway_dir = normalize(eye_light_dir-eye_look_dir);
-	out vec3 tbn_halfway_dir = eye_halfway_dir*eye_tbn_matrix;
+	out vec3 world_halfway_dir = normalize(world_light_dir-world_look_dir);
 
-	out vec3 tbn_zenith_dir = eye_zenith_dir*eye_tbn_matrix;
 	out float fog_coord = eye_vertex.z;
 
 	if(use_clipping)
 	{
 		for(int i=0; i<max_clip_planes; ++i)
-			gl_ClipDistance[i] = dot(eye_vertex, clip_planes[i].equation);
+			gl_ClipDistance[i] = dot(world_vertex, clip_planes[i].equation);
 	}
 
-	shadow_transform(eye_vertex);
+	shadow_transform(world_vertex);
 }
 
 virtual void custom_transform()
@@ -81,23 +79,20 @@ void main()
 virtual vec3 get_fragment_normal()
 {
 	if(use_normal_map)
-		return normalize(texture(normal_map, texcoord.xy).xyz*2.0-1.0);
+		return normalize(world_tbn_matrix*(texture(normal_map, texcoord.xy).xyz*2.0-1.0));
 	else
-		return vec3(0.0, 0.0, 1.0);
+		return normalize(world_normal);
 }
 
-virtual vec4 get_environment_sample(vec3 direction)
+virtual vec3 get_environment_sample(vec3 direction)
 {
-	return texture(environment_map, direction);
+	return texture(environment_map, env_world_matrix*direction).rgb;
 }
 
 virtual vec3 get_reflection(vec3 normal, vec3 look)
 {
 	vec3 reflect_dir = reflect(look, normal);
-	if(use_normal_map)
-		reflect_dir = eye_tbn_matrix*reflect_dir;
-
-	return get_environment_sample(env_eye_matrix*reflect_dir).rgb;
+	return get_environment_sample(reflect_dir);
 }
 
 vec3 apply_fog(vec3 color)
diff --git a/shaderlib/cooktorrance.glsl b/shaderlib/cooktorrance.glsl
index 2a03e2c5..8e95752f 100644
--- a/shaderlib/cooktorrance.glsl
+++ b/shaderlib/cooktorrance.glsl
@@ -133,11 +133,7 @@ vec3 cooktorrance_one_light_direct(vec3 normal, vec3 look, vec3 light, vec3 ligh
 
 vec3 cooktorrance_lighting(vec3 normal, vec3 look, vec3 base_color, float metalness, float roughness)
 {
-	vec3 light;
-	if(use_normal_map)
-		light = normalize(tbn_light_dir);
-	else
-		light = normalize(eye_light_dir);
+	vec3 light = normalize(world_light_dir);
 
 	float shadow = get_shadow_factor(0);
 	vec3 color = cooktorrance_one_light_direct(normal, look, light, light_sources[0].color, base_color, metalness, roughness)*shadow;
@@ -152,18 +148,8 @@ vec3 cooktorrance_lighting(vec3 normal, vec3 look, vec3 base_color, float metaln
 
 void main()
 {
-	vec3 normal;
-	vec3 look;
-	if(use_normal_map)
-	{
-		normal = get_fragment_normal();
-		look = normalize(tbn_look_dir);
-	}
-	else
-	{
-		normal = normalize(eye_normal);
-		look = normalize(eye_look_dir);
-	}
+	vec3 normal = get_fragment_normal();
+	vec3 look = normalize(world_look_dir);
 
 	vec4 base_color = get_base_color();
 	float metalness = get_metalness_value();
diff --git a/shaderlib/msp_interface.glsl b/shaderlib/msp_interface.glsl
index c4b27b11..e35b9848 100644
--- a/shaderlib/msp_interface.glsl
+++ b/shaderlib/msp_interface.glsl
@@ -9,12 +9,12 @@ struct ClipPlane
 	vec4 equation;
 };
 
-uniform mat4 eye_obj_matrix;
-uniform mat3 eye_obj_normal_matrix;
+uniform mat4 world_obj_matrix;
+uniform mat3 world_obj_normal_matrix;
 uniform Transform
 {
 	mat4 eye_world_matrix;
-	mat4 projection_matrix;
+	mat4 clip_eye_matrix;
 };
 
 uniform Lighting
@@ -23,7 +23,7 @@ uniform Lighting
 	LightSourceParameters light_sources[1];
 	vec4 ambient_color;
 	vec4 sky_color;
-	vec3 eye_zenith_dir;
+	vec3 world_zenith_dir;
 	float horizon_limit;
 	vec4 fog_color;
 	float fog_density;
diff --git a/shaderlib/phong.glsl b/shaderlib/phong.glsl
index 6b6de6ff..7d8dc295 100644
--- a/shaderlib/phong.glsl
+++ b/shaderlib/phong.glsl
@@ -94,11 +94,7 @@ vec3 phong_one_light(vec3 light, vec3 normal, vec3 look, vec3 light_color, vec3
 
 vec3 phong_lighting(vec3 normal, vec3 look, vec3 surface_diffuse, vec3 surface_specular, float shininess)
 {
-	vec3 light;
-	if(use_normal_map)
-		light = normalize(tbn_light_dir);
-	else
-		light = normalize(eye_light_dir);
+	vec3 light = normalize(world_light_dir);
 
 	vec3 color = phong_ambient(surface_diffuse);
 	float shadow = get_shadow_factor(0);
@@ -115,18 +111,8 @@ vec3 phong_lighting(vec3 normal, vec3 look, vec3 surface_diffuse, vec3 surface_s
 
 void main()
 {
-	vec3 normal;
-	vec3 look;
-	if(use_normal_map)
-	{
-		normal = get_fragment_normal();
-		look = normalize(tbn_look_dir);
-	}
-	else
-	{
-		normal = normalize(eye_normal);
-		look = normalize(eye_look_dir);
-	}
+	vec3 normal = get_fragment_normal();
+	vec3 look = normalize(world_look_dir);
 
 	vec4 surface_diffuse = get_diffuse_color();
 	vec3 surface_specular = get_specular_color();
diff --git a/shaderlib/shadow.glsl b/shaderlib/shadow.glsl
index f0338b95..04cf6832 100644
--- a/shaderlib/shadow.glsl
+++ b/shaderlib/shadow.glsl
@@ -3,7 +3,7 @@ import msp_interface;
 uniform ShadowMap
 {
 	float shadow_darkness;
-	mat4 shd_eye_matrix;
+	mat4 shd_world_matrix;
 };
 
 uniform sampler2DShadow shadow_map;
@@ -11,9 +11,9 @@ uniform sampler2DShadow shadow_map;
 layout(constant_id=auto) const bool use_shadow_map = false;
 
 #pragma MSP stage(vertex)
-void shadow_transform(vec4 eye_vertex)
+void shadow_transform(vec4 world_vertex)
 {
-	out vec3 shadow_coord = (shd_eye_matrix*eye_vertex).xyz;
+	out vec3 shadow_coord = (shd_world_matrix*world_vertex).xyz;
 }
 
 #pragma MSP stage(fragment)
diff --git a/source/effects/environmentmap.cpp b/source/effects/environmentmap.cpp
index c714a56f..353f9841 100644
--- a/source/effects/environmentmap.cpp
+++ b/source/effects/environmentmap.cpp
@@ -47,6 +47,8 @@ void EnvironmentMap::init(unsigned s, PixelFormat f)
 		faces[i].camera.set_aspect_ratio(1);
 		faces[i].camera.set_depth_clip(0.1, 100);
 	}
+
+	shdata.uniform("env_world_matrix", LinAl::SquareMatrix<float, 3>::identity());
 }
 
 void EnvironmentMap::set_depth_clip(float n, float f)
@@ -121,9 +123,6 @@ void EnvironmentMap::render(Renderer &renderer, Tag tag) const
 
 	Renderer::Push _push_rend(renderer);
 
-	const Matrix &camera_matrix = renderer.get_camera()->get_object_matrix();
-	shdata.uniform("env_eye_matrix", camera_matrix.block<3, 3>(0, 0));
-
 	renderer.set_texture("environment_map", &env_tex, &sampler);
 	renderer.add_shader_data(shdata);
 	renderer.render(renderable, tag);
diff --git a/source/effects/environmentmap.h b/source/effects/environmentmap.h
index 68bce7de..5d1e7c91 100644
--- a/source/effects/environmentmap.h
+++ b/source/effects/environmentmap.h
@@ -39,7 +39,7 @@ private:
 	Renderbuffer depth_buf;
 	Face faces[6];
 	const Sampler &sampler;
-	mutable ProgramData shdata;
+	ProgramData shdata;
 	bool rendered;
 	unsigned update_interval;
 	unsigned update_delay;
diff --git a/source/effects/shadowmap.cpp b/source/effects/shadowmap.cpp
index 488a3427..11bb706e 100644
--- a/source/effects/shadowmap.cpp
+++ b/source/effects/shadowmap.cpp
@@ -43,6 +43,7 @@ void ShadowMap::init(unsigned s)
 	fbo.require_complete();
 
 	set_darkness(0.7);
+	shdata.uniform("shd_world_matrix", Matrix());
 }
 
 void ShadowMap::set_target(const Vector3 &t, float r)
@@ -88,6 +89,8 @@ void ShadowMap::setup_frame(Renderer &renderer)
 	shadow_matrix.translate(-0.5, -0.5, depth_bias/size-0.5);
 	shadow_matrix.invert();
 
+	shdata.uniform("shd_world_matrix", shadow_matrix);
+
 	BindRestore bind_fbo(fbo);
 	Bind bind_depth(DepthTest::lequal());
 	fbo.clear(DEPTH_BUFFER_BIT);
@@ -112,13 +115,6 @@ void ShadowMap::render(Renderer &renderer, Tag tag) const
 	if(!enabled_passes.count(tag))
 		return renderer.render(renderable, tag);
 
-	if(const Camera *camera = renderer.get_camera())
-		/* Multiply by camera's object matrix to form a matrix that transforms
-		from eye space to shadow space. */
-		shdata.uniform("shd_eye_matrix", shadow_matrix*camera->get_object_matrix());
-	else
-		shdata.uniform("shd_eye_matrix", shadow_matrix);
-
 	Renderer::Push _push_rend(renderer);
 
 	renderer.set_texture("shadow_map", &depth_buf, &sampler);
diff --git a/source/effects/shadowmap.h b/source/effects/shadowmap.h
index 5d8bf509..d618c061 100644
--- a/source/effects/shadowmap.h
+++ b/source/effects/shadowmap.h
@@ -34,7 +34,7 @@ private:
 	Vector3 target;
 	float radius;
 	float depth_bias;
-	mutable ProgramData shdata;
+	ProgramData shdata;
 	bool rendered;
 
 public:
diff --git a/source/materials/lighting.cpp b/source/materials/lighting.cpp
index 1f1c66d9..70b819ce 100644
--- a/source/materials/lighting.cpp
+++ b/source/materials/lighting.cpp
@@ -94,14 +94,11 @@ void Lighting::update_shader_data(ProgramData &shdata, const Matrix &view_matrix
 {
 	shdata.uniform("ambient_color", ambient);
 	shdata.uniform("sky_color", sky_color);
-	shdata.uniform("eye_zenith_dir", view_matrix.block<3, 3>(0, 0)*zenith_direction);
+	shdata.uniform("world_zenith_dir", zenith_direction);
 	shdata.uniform("horizon_limit", horizon_angle.radians());
 	shdata.uniform("fog_color", fog_color);
 	shdata.uniform("fog_density", fog_density);
 
-	// For backwards compatibility
-	shdata.uniform("eye_sky_dir", view_matrix.block<3, 3>(0, 0)*zenith_direction);
-
 	for(unsigned i=0; i<lights.size(); ++i)
 		if(lights[i])
 			lights[i]->update_shader_data(shdata, view_matrix, i);
diff --git a/source/render/renderer.cpp b/source/render/renderer.cpp
index 2485a9e2..5d0bf6b8 100644
--- a/source/render/renderer.cpp
+++ b/source/render/renderer.cpp
@@ -44,7 +44,7 @@ void Renderer::init()
 	shdata_stack.reserve(32);
 	state = &state_stack.back();
 
-	standard_shdata.uniform("projection_matrix", Matrix());
+	standard_shdata.uniform("clip_eye_matrix", Matrix());
 	standard_shdata.uniform("eye_world_matrix", Matrix());
 }
 
@@ -56,21 +56,21 @@ Renderer::~Renderer()
 void Renderer::set_camera(const Camera &c)
 {
 	state->camera = &c;
-	standard_shdata.uniform("projection_matrix", state->camera->get_projection_matrix());
+	standard_shdata.uniform("clip_eye_matrix", state->camera->get_projection_matrix());
 	standard_shdata.uniform("eye_world_matrix", state->camera->get_view_matrix());
 	changed |= STANDARD_SHDATA;
-	set_matrix(state->camera->get_view_matrix());
+	set_matrix(Matrix());
 }
 
 void Renderer::set_matrix(const Matrix &matrix)
 {
-	state->modelview_matrix = matrix;
+	state->model_matrix = matrix;
 	changed |= MATRIX;
 }
 
 void Renderer::transform(const Matrix &matrix)
 {
-	state->modelview_matrix *= matrix;
+	state->model_matrix *= matrix;
 	changed |= MATRIX;
 }
 
@@ -159,10 +159,9 @@ void Renderer::set_material(const Material *m)
 void Renderer::set_lighting(const Lighting *l)
 {
 	state->lighting = l;
-	state->lighting_matrix = state->modelview_matrix;
 	if(l)
 	{
-		l->update_shader_data(standard_shdata, state->lighting_matrix);
+		l->update_shader_data(standard_shdata, Matrix());
 		changed |= STANDARD_SHDATA;
 	}
 }
@@ -170,10 +169,9 @@ void Renderer::set_lighting(const Lighting *l)
 void Renderer::set_clipping(const Clipping *c)
 {
 	state->clipping = c;
-	state->clipping_matrix = state->modelview_matrix;
 	if(c)
 	{
-		c->update_shader_data(standard_shdata, state->clipping_matrix);
+		c->update_shader_data(standard_shdata, Matrix());
 		changed |= STANDARD_SHDATA;
 	}
 }
@@ -251,32 +249,29 @@ void Renderer::pop_state()
 	{
 		if(state->camera)
 		{
-			standard_shdata.uniform("projection_matrix", state->camera->get_projection_matrix());
+			standard_shdata.uniform("clip_eye_matrix", state->camera->get_projection_matrix());
 			standard_shdata.uniform("eye_world_matrix", state->camera->get_view_matrix());
 		}
 		else
 		{
-			standard_shdata.uniform("projection_matrix", Matrix());
+			standard_shdata.uniform("clip_eye_matrix", Matrix());
 			standard_shdata.uniform("eye_world_matrix", Matrix());
 		}
 		changed |= STANDARD_SHDATA;
 	}
-	/* This actually should compare the relevant matrices rather than check for
-	camera, but in practice lighting and clipping is set right after the camera
-	and a boolean check is much faster than matrix comparison. */
-	if(state->lighting!=old_lighting || camera_changed)
+	if(state->lighting!=old_lighting)
 	{
 		if(state->lighting)
 		{
-			state->lighting->update_shader_data(standard_shdata, state->lighting_matrix);
+			state->lighting->update_shader_data(standard_shdata, Matrix());
 			changed |= STANDARD_SHDATA;
 		}
 	}
-	if(state->clipping!=old_clipping || camera_changed)
+	if(state->clipping!=old_clipping)
 	{
 		if(state->clipping)
 		{
-			state->clipping->update_shader_data(standard_shdata, state->clipping_matrix);
+			state->clipping->update_shader_data(standard_shdata, Matrix());
 			changed |= STANDARD_SHDATA;
 		}
 	}
@@ -291,7 +286,7 @@ void Renderer::end()
 	if(default_camera)
 		set_camera(*default_camera);
 	else
-		standard_shdata.uniform("projection_matrix", Matrix());
+		standard_shdata.uniform("clip_eye_matrix", Matrix());
 	shdata_stack.clear();
 	excluded.clear();
 
@@ -372,10 +367,10 @@ void Renderer::apply_state()
 
 	if(changed&MATRIX)
 	{
-		standard_shdata.uniform("eye_obj_matrix", state->modelview_matrix);
-		LinAl::SquareMatrix<float, 3> nm = state->modelview_matrix.block<3, 3>(0, 0);
+		standard_shdata.uniform("world_obj_matrix", state->model_matrix);
+		LinAl::SquareMatrix<float, 3> nm = state->model_matrix.block<3, 3>(0, 0);
 		nm = transpose(invert(nm));
-		standard_shdata.uniform("eye_obj_normal_matrix", nm);
+		standard_shdata.uniform("world_obj_normal_matrix", nm);
 		changed = (changed&~MATRIX)|STANDARD_SHDATA;
 	}
 
diff --git a/source/render/renderer.h b/source/render/renderer.h
index 1a84d8bf..27087197 100644
--- a/source/render/renderer.h
+++ b/source/render/renderer.h
@@ -86,14 +86,12 @@ private:
 	struct State
 	{
 		const Camera *camera;
-		Matrix modelview_matrix;
+		Matrix model_matrix;
 		unsigned texture_count;
 		unsigned lowest_effect_texunit;
 		const Material *material;
 		const Lighting *lighting;
-		Matrix lighting_matrix;
 		const Clipping *clipping;
-		Matrix clipping_matrix;
 		const Program *shprog;
 		unsigned shdata_count;
 		const VertexSetup *vertex_setup;
@@ -129,20 +127,19 @@ private:
 public:
 	~Renderer();
 
-	/** Sets the camera to render from.  The modelview matrix is reset to the
-	camera's view matrix. */
+	/** Sets the camera to render from.  The model matrix is reset to identity. */
 	void set_camera(const Camera &);
 
 	const Camera *get_camera() const { return state->camera; }
 
-	/** Replaces the Renderer's modelview matrix. */
+	/** Replaces the Renderer's model matrix. */
 	void set_matrix(const Matrix &);
 
-	/** Applies a transform to the Renderer's modelview matrix. */
+	/** Applies a transform to the Renderer's model matrix. */
 	void transform(const Matrix &);
 
-	/** Returns the current modelview matrix. */
-	const Matrix &get_matrix() const { return state->modelview_matrix; }
+	/** Returns the current model matrix. */
+	const Matrix &get_matrix() const { return state->model_matrix; }
 
 	void set_texture(Tag, const Texture *, const Sampler * = 0);
 private:
diff --git a/source/render/scene.cpp b/source/render/scene.cpp
index c0a4e1c5..70a9e94b 100644
--- a/source/render/scene.cpp
+++ b/source/render/scene.cpp
@@ -24,7 +24,7 @@ bool Scene::setup_frustum(const Renderer &renderer) const
 	if(!camera)
 		return false;
 
-	culling_matrix = renderer.get_matrix();
+	culling_matrix = camera->get_view_matrix()*renderer.get_matrix();
 
 	if(camera->is_orthographic())
 	{
-- 
2.43.0