add block material shaders

- 'shader' property of block materials: shaders/materials/<name>.glslv, .glslf with material_vertex / material_fragment hooks and #param uniforms
- material shaders code is included into main, translucent and shadows programs through generated headers, no extra draw calls
- chunk vertex normal.w byte replaced with 'flags': bit 7 - emission flag, bits 0-6 - material shader index (vertex format size is not changed)
- doc/*/block-materials.md

res/shaders/clouds.glslv

@@ -41,7 +41,7 @@ void main() {
     a_fog = calc_fog(length(viewmodel * vec4(pos3d * FOG_POS_SCALE, 0.0)) / 256.0);
 #endif
 
-    a_emission = v_normal.w;
+    a_emission = unpack_emission(v_normal.w);
 
     vec4 viewmodelpos = u_view * a_modelpos;
     a_position = viewmodelpos.xyz;

res/shaders/lib/commons.glsl

@@ -8,4 +8,13 @@ vec3 apply_planet_curvature(vec3 modelPos, vec3 pos3d) {
     return modelPos;
 }
 
+// chunk vertex flags (normal.w): bit 7 - emission flag, bits 0-6 - material
+float unpack_emission(float w) {
+    return float(int(w * 255.0 + 0.5) >> 7);
+}
+
+int unpack_material(float w) {
+    return int(w * 255.0 + 0.5) & 127;
+}
+
 #endif // COMMONS_GLSL_

res/shaders/lib/world_fragment_header.glsl

@@ -11,6 +11,7 @@ in vec3 a_realnormal;
 in vec3 a_skyLight;
 in vec4 a_modelpos;
 in float a_emission;
+flat in int a_material;
 
 #include <world_uniforms>
 

res/shaders/lib/world_vertex_header.glsl

@@ -11,6 +11,7 @@ out vec3 a_realnormal;
 out vec3 a_skyLight;
 out vec4 a_modelpos;
 out float a_emission;
+flat out int a_material;
 
 #include <world_uniforms>
 

res/shaders/main.glslf

@@ -15,8 +15,12 @@ uniform bool u_alphaClip;
 uniform bool u_debugLights;
 uniform bool u_debugNormals;
 
+#include <__materials_fragment__>
+
 void main() {
-    vec4 texColor = texture(u_texture0, a_texCoord);
+    vec4 texColor = apply_material_fragment(
+        a_material, texture(u_texture0, a_texCoord)
+    );
     float alpha = texColor.a;
     if (u_alphaClip) {
         if (alpha < 0.2f)

res/shaders/main.glslv

@@ -14,11 +14,16 @@ uniform float u_dayTime;
 
 out vec4 a_torchLight;
 
+#include <__materials_vertex__>
+
 void main() {
+    a_material = unpack_material(v_normal.w);
+    a_realnormal = v_normal.xyz * 2.0 - 1.0;
     a_modelpos = u_model * vec4(v_position, 1.0f);
+    // material shader may also modify a_realnormal
+    a_modelpos.xyz = apply_material_vertex(a_material, a_modelpos.xyz);
     vec3 pos3d = a_modelpos.xyz - u_cameraPos;
 
-    a_realnormal = v_normal.xyz * 2.0 - 1.0;
     a_normal = calc_screen_normal(a_realnormal);
 
     a_torchLight = vec4(calc_torch_light(
@@ -37,7 +42,7 @@ void main() {
     a_fog = calc_fog(length(viewmodel * vec4(pos3d * FOG_POS_SCALE, 0.0)) / 256.0);
 #endif
 
-    a_emission = v_normal.w;
+    a_emission = unpack_emission(v_normal.w);
 
     vec4 viewmodelpos = u_view * a_modelpos;
     a_position = viewmodelpos.xyz;

res/shaders/shadows.glslf

@@ -1,9 +1,13 @@
-in vec2 a_texCoord;
+#include <world_fragment_header>
 
 uniform sampler2D u_texture0;
 
+#include <__materials_fragment__>
+
 void main() {
-    vec4 tex_color = texture(u_texture0, a_texCoord);
+    vec4 tex_color = apply_material_fragment(
+        a_material, texture(u_texture0, a_texCoord)
+    );
     if (tex_color.a < 0.5) {
         discard;
     }

res/shaders/shadows.glslv

@@ -5,13 +5,18 @@ layout (location = 1) in vec2 v_texCoord;
 layout (location = 2) in vec4 v_light;
 layout (location = 3) in vec4 v_normal;
 
-out vec2 a_texCoord;
+// same vertex stage interface as world shaders for material shaders
+#include <world_vertex_header>
 
-uniform mat4 u_model;
-uniform mat4 u_proj;
-uniform mat4 u_view;
+uniform float u_dayTime;
+
+#include <__materials_vertex__>
 
 void main() {
     a_texCoord = v_texCoord;
-    gl_Position = u_proj * u_view * u_model * vec4(v_position, 1.0f);
+    a_material = unpack_material(v_normal.w);
+    a_realnormal = v_normal.xyz * 2.0 - 1.0;
+    a_modelpos = u_model * vec4(v_position, 1.0f);
+    a_modelpos.xyz = apply_material_vertex(a_material, a_modelpos.xyz);
+    gl_Position = u_proj * u_view * a_modelpos;
 }

res/shaders/translucent.glslf

@@ -14,8 +14,12 @@ uniform bool u_debugNormals;
 
 #include <shadows>
 
+#include <__materials_fragment__>
+
 void main() {
-    vec4 texColor = texture(u_texture0, a_texCoord);
+    vec4 texColor = apply_material_fragment(
+        a_material, texture(u_texture0, a_texCoord)
+    );
     float alpha = texColor.a;
     if (u_alphaClip) {
         if (alpha < 0.2f)

res/shaders/translucent.glslv

@@ -14,11 +14,15 @@ out vec4 a_torchLight;
 
 uniform float u_dayTime;
 
+#include <__materials_vertex__>
+
 void main() {
+    a_material = unpack_material(v_normal.w);
+    a_realnormal = v_normal.xyz * 2.0 - 1.0;
     a_modelpos = u_model * vec4(v_position, 1.0f);
+    a_modelpos.xyz = apply_material_vertex(a_material, a_modelpos.xyz);
     vec3 pos3d = a_modelpos.xyz - u_cameraPos;
 
-    a_realnormal = v_normal.xyz * 2.0 - 1.0;
     a_normal = calc_screen_normal(a_realnormal);
 
     a_torchLight = vec4(calc_torch_light(
@@ -33,7 +37,7 @@ void main() {
     mat4 viewmodel = u_view * u_model;
     a_distance = length(viewmodel * vec4(pos3d, 0.0));
     a_fog = calc_fog(length(viewmodel * vec4(pos3d * FOG_POS_SCALE, 0.0)) / 256.0);
-    a_emission = v_normal.w;
+    a_emission = unpack_emission(v_normal.w);
 
     vec4 viewmodelpos = u_view * a_modelpos;
     a_position = viewmodelpos.xyz;