Add better shader for dirt

data/shaders/sp_advanced_terrain.frag

@@ -0,0 +1,59 @@
+in vec3 bitangent;
+in vec4 color;
+in float hue_change;
+in vec3 normal;
+in vec3 tangent;
+in vec2 uv;
+in float camdist;
+in vec4 world_position;
+in vec3 world_normal;
+
+layout(location = 0) out vec4 o_diffuse_color;
+layout(location = 1) out vec4 o_normal_color;
+
+#stk_include "utils/encode_normal.frag"
+#stk_include "utils/rgb_conversion.frag"
+#stk_include "utils/sp_texture_sampling.frag"
+
+float overlay(float bg, float fg)
+{
+    return bg < 0.5 ? (2.0 * bg * fg) : (1.0 - 2.0 * (1.0 - bg) * (1.0 - fg));
+}
+
+void main()
+{
+    vec4 col = multi_sampleTextureLayer0(uv, camdist);
+    vec4 rock = multi_sampleTextureLayer4(uv, camdist);
+    
+    vec2 uuv = vec2(world_position.x, world_position.z);
+
+
+    float mask_2 = multi_sampleTextureLayer5(uv, camdist).r;
+    mask_2 = pow(mask_2, 1.5);
+
+    float up_mask = dot(vec3(0., 1., 0.), world_normal);
+    up_mask = pow(up_mask + (up_mask * 0.1), 2);
+    up_mask = clamp(up_mask, 0.0, 1.0);
+    //vec3 final_color = mix(col.rgb, rock.rgb, overlay(color.r,  mask_2));
+    vec3 final_color = mix(rock.rgb, col.rgb, overlay(up_mask,  mask_2));
+    //vec3 final_color = mix(vec3(1.0, 0.0, 0.0), vec3(0.0, 1.0, 0.0), overlay(color.r,  mask_2));
+
+#if defined(Advanced_Lighting_Enabled)
+    vec4 layer_2 = multi_sampleTextureLayer2(uv, camdist);
+    vec4 layer_3 = multi_sampleTextureLayer3(uv, camdist);
+    o_diffuse_color = vec4(final_color, layer_2.z);
+
+    vec3 tangent_space_normal = 2.0 * layer_3.xyz - 1.0;
+    vec3 frag_tangent = normalize(tangent);
+    vec3 frag_bitangent = normalize(bitangent);
+    vec3 frag_normal = normalize(normal);
+    mat3 t_b_n = mat3(frag_tangent, frag_bitangent, frag_normal);
+
+    vec3 world_normal = t_b_n * tangent_space_normal;
+
+    o_normal_color.xy = 0.5 * EncodeNormal(normalize(world_normal)) + 0.5;
+    o_normal_color.zw = layer_2.xy;
+#else
+    o_diffuse_color = vec4(final_color, 1.0);
+#endif
+}

data/shaders/sp_kart_dirt.frag

@@ -0,0 +1,82 @@
+in vec3 bitangent;
+in vec4 color;
+in float hue_change;
+in vec3 normal;
+in vec3 tangent;
+in vec2 uv;
+in vec4 world_position;
+
+layout(location = 0) out vec4 o_diffuse_color;
+layout(location = 1) out vec4 o_normal_color;
+
+#stk_include "utils/encode_normal.frag"
+#stk_include "utils/rgb_conversion.frag"
+#stk_include "utils/sp_texture_sampling.frag"
+
+uniform sampler2D g_dirt_albedo;
+uniform sampler2D g_dirt_normal;
+uniform float dirt_factor;
+
+void main()
+{
+    // Triplanar detail map
+    vec2 xyuv = vec2(world_position.x, world_position.y);
+    vec3 dirt = texture(g_dirt_albedo, uv * 4).rgb;
+
+    vec4 col = sampleTextureLayer0(uv);
+    if (hue_change > 0.0)
+    {
+        float mask = col.a;
+        vec3 old_hsv = rgbToHsv(col.rgb);
+        float mask_step = step(mask, 0.5);
+#if !defined(Advanced_Lighting_Enabled)
+        // For similar color
+        float saturation = mask * 1.825; // 2.5 * 0.5 ^ (1. / 2.2)
+#else
+        float saturation = mask * 2.5;
+#endif
+        vec2 new_xy = mix(vec2(old_hsv.x, old_hsv.y), vec2(hue_change,
+            max(old_hsv.y, saturation)), vec2(mask_step, mask_step));
+        vec3 new_color = hsvToRgb(vec3(new_xy.x, new_xy.y, old_hsv.z));
+        col = vec4(new_color.r, new_color.g, new_color.b, 1.0);
+    }
+
+    float dirtMask = sampleTextureLayer4(uv).r;
+    float nitroMask = sampleTextureLayer4(uv).g;
+    //dirtMask *= dirtMask;
+    // Dirt factor
+    dirtMask = 1.0 - dirtMask;
+    dirtMask *= clamp(dirt_factor, 0.0, 1.0);
+    nitroMask *= clamp(dirt_factor, 0.0, 1.0);
+    vec3 final_color = col.xyz * color.xyz;
+    //dirtMask = step(dirtMask,dirt_factor - 0.5);
+    final_color = mix(final_color, dirt, dirtMask);
+
+    final_color = mix(final_color, vec3(0, 0.415, 0.639), nitroMask); 
+
+#if defined(Advanced_Lighting_Enabled)
+    vec4 layer_2 = sampleTextureLayer2(uv);
+    vec4 layer_3 = sampleTextureLayer3(uv);
+    // Part emitting light
+    layer_2.z = mix(layer_2.z, 1.0, nitroMask);
+    o_diffuse_color = vec4(final_color, layer_2.z);
+    // Dirt part should not be glossy
+    layer_2.r = mix(layer_2.r, 0.0, dirtMask);
+    // Mix the normal map for the dirt
+    vec4 dirt_nor = texture(g_dirt_normal, uv * 4);
+    layer_3 = mix(layer_3, dirt_nor, dirtMask);
+
+    vec3 tangent_space_normal = 2.0 * layer_3.xyz - 1.0;
+    vec3 frag_tangent = normalize(tangent);
+    vec3 frag_bitangent = normalize(bitangent);
+    vec3 frag_normal = normalize(normal);
+    mat3 t_b_n = mat3(frag_tangent, frag_bitangent, frag_normal);
+
+    vec3 world_normal = t_b_n * tangent_space_normal;
+
+    o_normal_color.xy = 0.5 * EncodeNormal(normalize(world_normal)) + 0.5;
+    o_normal_color.zw = layer_2.xy;
+#else
+    o_diffuse_color = vec4(final_color, 1.0);
+#endif
+}

data/shaders/sp_normal_map.frag

@@ -23,7 +23,7 @@ void main()
     detail *= 2.5;
 
     vec4 col = sampleTextureLayer0(uv);
-    col = (col - detail) + 0.5;
+    //col = (col - detail) + 0.5;
     if (hue_change > 0.0)
     {
         float mask = col.a;

data/shaders/sps_13_advancedTerrain.xml

@@ -0,0 +1,13 @@
+<spshader>
+    <shader-info name="advancedTerrain" fallback-shader="solid" use-tangents="Y" srgb="Y Y N N Y N"/>
+    <first-pass vertex-shader="sp_pass.vert"
+        fragment-shader="sp_advanced_terrain.frag">
+    </first-pass>
+    <shadow-pass vertex-shader="sp_shadow.vert"
+        fragment-shader="white.frag">
+    </shadow-pass>
+    <uniform-assigners>
+        <uniform-assigner name="layer"
+        function="shadowCascadeUniformAssigner"/>
+    </uniform-assigners>
+</spshader>

data/shaders/sps_14_kart.xml

@@ -0,0 +1,23 @@
+<spshader>
+    <shader-info name="kartDirt" fallback-shader="solid" use-tangents="Y"/>
+    <first-pass vertex-shader="sp_pass.vert"
+        fragment-shader="sp_kart_dirt.frag"
+        skinned-mesh-shader="sp_skinning.vert">
+    <prefilled-textures>
+            <prefilled-texture name="g_dirt_albedo" file="gfx_kartDirt_a_Albedo.png"
+                 srgb="Y" sampler="trilinear"/>
+            <prefilled-texture name="g_dirt_normal" file="gfx_kartDirt_a_Normal.png"
+                 sampler="trilinear"/>
+    </prefilled-textures>
+    </first-pass>
+    <shadow-pass vertex-shader="sp_shadow.vert"
+        fragment-shader="white.frag"
+        skinned-mesh-shader="sp_skinning_shadow.vert">
+    </shadow-pass>
+    <uniform-assigners>
+        <uniform-assigner name="layer"
+        function="shadowCascadeUniformAssigner"/>
+        <uniform-assigner name="dirt_factor"
+            function="dirtFactorUniformAssigner"/>
+    </uniform-assigners>
+</spshader>

data/shaders/utils/sp_texture_sampling.frag

@@ -136,3 +136,26 @@ vec4 sampleTextureLayer5(vec2 uv)
 {
     return texture(tex_layer_5, uv);
 }
+
+vec4 multi_sampleTextureLayer5(vec2 uv, float distance)
+{
+
+    vec4 l_col = sampleTextureLayer5(uv * LOW_SAMPLING);
+    vec4 m_col = sampleTextureLayer5(uv * MEDIUM_SAMPLING);
+    vec4 h_col = sampleTextureLayer5(uv * HIGH_SAMPLING);
+
+    // From Low to medium
+    float factor = distance * 0.02;
+    factor = pow(factor, 2.5);
+    factor = clamp(factor, 0.0, 1.0);
+    vec4 f_col = mix(m_col, l_col, factor);
+    
+    // From medium to high
+    factor = distance * 0.1;
+    factor = pow(factor, 2.5);
+    factor = clamp(factor, 0.0, 1.0);
+
+    f_col = mix(h_col, f_col, factor);
+
+    return f_col;
+}

src/graphics/skid_marks.cpp

@@ -46,8 +46,8 @@ SkidMarks::SkidMarks(const AbstractKart& kart, float width) : m_kart(kart)
 {
     m_width = width;
     m_material = material_manager->getMaterialSPM("skidmarks.png", "",
-        "alphablend");
-    m_shader = SP::SPShaderManager::get()->getSPShader("alphablend");
+        "alphatest");
+    m_shader = SP::SPShaderManager::get()->getSPShader("alphatest");
     assert(m_shader);
     auto texture = SP::SPTextureManager::get()->getTexture(
         m_material->getSamplerPath(0), m_material,

src/graphics/sp/sp_shader_manager.cpp

@@ -18,6 +18,7 @@
 #include "graphics/sp/sp_shader_manager.hpp"
 #include "io/file_manager.hpp"
 #include "io/xml_node.hpp"
+#include "graphics/camera.hpp"
 #include "graphics/central_settings.hpp"
 #include "graphics/sp/sp_base.hpp"
 #include "graphics/sp/sp_shader.hpp"
@@ -25,6 +26,7 @@
 #include "graphics/sp/sp_texture_manager.hpp"
 #include "graphics/sp/sp_uniform_assigner.hpp"
 #include "tracks/track.hpp"
+#include "karts/abstract_kart.hpp"
 #include "utils/string_utils.hpp"
 #include "utils/log.hpp"
 
@@ -60,6 +62,26 @@ SPShaderManager::SPShaderManager()
                 ua->setValue(sp_wind_dir);
             }
         },
+        { "dirtFactorUniformAssigner", [](SPUniformAssigner* ua)
+            {
+                AbstractKart* k = NULL;
+                if (Camera::getNumCameras() > 0)
+                {
+                    if (Camera::getActiveCamera() != NULL)
+                    {
+                        k = Camera::getActiveCamera()->getKart();
+                    }
+                }
+                if (k)
+                {
+                    ua->setValue(k->getDirtFactor());
+                }
+                else
+                {
+                    ua->setValue(0.0f);
+                }
+            }
+        },
         { "isDuringDayUniformAssigner", [](SPUniformAssigner* ua)
             {
                 int is_during_day = Track::getCurrentTrack() ?

src/karts/abstract_kart.hpp

@@ -356,6 +356,9 @@ public:
     /** True if the wheels are touching the ground. */
     virtual bool isOnGround() const = 0;
     // ------------------------------------------------------------------------
+    /** Returns the dirt factor (how dirty the kart is). */
+    virtual float getDirtFactor() const = 0;
+    // ------------------------------------------------------------------------
     /** Returns the slipstream object of this kart. */
     virtual const SlipStream* getSlipstream() const = 0;
     // ------------------------------------------------------------------------

src/karts/kart.cpp

@@ -377,6 +377,8 @@ void Kart::reset()
     m_view_blocked_by_plunger = 0;
     m_has_caught_nolok_bubblegum = false;
     m_is_jumping           = false;
+    m_dirt_factor          = 0.0f;
+    m_dirt_reset_counter   = 0.0f;
 
     for (int i=0;i<m_xyz_history_size;i++)
     {
@@ -1164,6 +1166,14 @@ bool Kart::isOnGround() const
           && !getKartAnimation());
 }   // isOnGround
 
+//-----------------------------------------------------------------------------
+/** The kart as a dirt factor (if the player skids and go in dirty places)
+ */
+ float Kart::getDirtFactor() const
+ {
+     return m_dirt_factor;
+ }   // getDirtFactor
+
 //-----------------------------------------------------------------------------
 /** The kart is near the ground, but not necessarily on it (small jumps). This
  *  is used to determine when to stop flying.
@@ -1890,6 +1900,29 @@ void Kart::handleMaterialGFX(float dt)
 {
     const Material *material = getMaterial();
 
+    if (m_skidding->isSkidding())
+    {
+        m_dirt_factor += 0.001f;
+        if (m_dirt_factor > 1.0f)
+        {
+            m_dirt_factor = 1.0f;
+        }
+        m_dirt_reset_counter = 2.0f;
+    }
+    else
+    {
+        m_dirt_reset_counter -= 0.01f;
+        if (m_dirt_reset_counter < 0.0f)
+        {
+            m_dirt_reset_counter = 0.0f;
+            m_dirt_factor -= 0.002f;
+            if (m_dirt_factor < 0.0f)
+            {
+                m_dirt_factor = 0.0f;
+            }
+        }
+    }
+
     // First test: give the terrain effect, if the kart is
     // on top of a surface (i.e. not falling), actually touching
     // something with the wheels, and the material has not the

src/karts/kart.hpp

@@ -166,6 +166,12 @@ protected:
      *  the kart is squashed. */
     float        m_squash_time;
 
+    /** How dirty the kart is, 0 = clean */
+    float        m_dirt_factor;
+
+    /** Counter to reset the dirt */
+    float        m_dirt_reset_counter;
+
     /** Current leaning of the kart. */
     float        m_current_lean;
 
@@ -453,6 +459,9 @@ public:
     /** True if the wheels are touching the ground. */
     virtual bool isOnGround() const OVERRIDE;
     // ------------------------------------------------------------------------
+    /** Returns the dirt factor (how dirty the kart is). */
+    virtual float getDirtFactor() const OVERRIDE;
+    // ------------------------------------------------------------------------
     /** Returns true if the kart is close to the ground, used to dis/enable
      *  the upright constraint to allow for more realistic explosions. */
     bool isNearGround() const;