Implement Painter's algorithm, fix Sliced

config/settings.template.ron

@@ -50,6 +50,7 @@
 		// RayMipTraced (mip_count: 10, max_jumps: 25, max_steps: 100, debug: false),
 		// Scattered( density: (2, 2, 2) ),
 		// Sliced,
+		// Painted( density: 0.1, min_divisor: 0.5 ),
 		debug: (
 			max_vertices: 512,
 			collision_shapes: false,

res/shader/terrain/locals.inc.glsl

@@ -0,0 +1,29 @@
+layout(set = 1, binding = 1) uniform c_Locals {
+    uvec4 u_ScreenSize;      // XY = size
+    uvec4 u_Params;
+    vec4 u_CamOriginDir;	// XY = origin, ZW = dir
+    vec4 u_SampleRange;		// XY = X range, ZW = y range
+};
+
+vec2 generate_scatter_pos(vec2 source_coord) {
+    float y;
+    if (true) {
+        float y_sqrt = mix(
+            sqrt(abs(u_SampleRange.z)) * sign(u_SampleRange.z),
+            sqrt(abs(u_SampleRange.w)) * sign(u_SampleRange.w),
+            source_coord.y
+        );
+        y = y_sqrt * y_sqrt * sign(y_sqrt);
+    } else {
+        y = mix(u_SampleRange.z, u_SampleRange.w, source_coord.y);
+    }
+
+    float x_limit = mix(
+        u_SampleRange.x, u_SampleRange.y,
+        (y - u_SampleRange.z) / (u_SampleRange.w - u_SampleRange.z)
+    );
+    float x = mix(-x_limit, x_limit, source_coord.x);
+
+    return u_CamOriginDir.xy + u_CamOriginDir.zw * y +
+        vec2(u_CamOriginDir.w, -u_CamOriginDir.z) * x;
+}

res/shader/terrain/paint.glsl

@@ -0,0 +1,37 @@
+//!include vs:globals.inc vs:terrain/locals.inc vs:surface.inc fs:surface.inc fs:color.inc
+
+layout(location = 0) varying vec3 v_TexCoord;
+layout(location = 1) flat varying uint v_Type;
+
+#ifdef SHADER_VS
+
+void main() {
+    float total_pixels = float(u_ScreenSize.x * u_ScreenSize.y);
+    uint pixel_index = uint(total_pixels * float(gl_InstanceIndex) / float(u_Params.x));
+
+    uvec2 pixel_pos = uvec2(pixel_index % u_ScreenSize.x, pixel_index / u_ScreenSize.x);
+    vec2 source_coord = 2.0 * vec2(pixel_pos) / vec2(u_ScreenSize.xy) - 1.0;
+    vec2 pos = generate_scatter_pos(source_coord);
+
+    Surface suf = get_surface(pos);
+    float altitude = gl_VertexIndex == 3 ? suf.high_alt :
+        gl_VertexIndex == 2 ? suf.low_alt + suf.delta :
+        gl_VertexIndex == 1 ? suf.low_alt : 0.0;
+
+    v_Type = gl_VertexIndex < 2 ? suf.low_type : suf.high_type;
+    v_TexCoord = vec3(suf.tex_coord, altitude / u_TextureScale.z);
+    gl_Position = u_ViewProj * vec4(pos, altitude, 1.0);
+}
+#endif //VS
+
+
+#ifdef SHADER_FS
+//imported: Surface, u_TextureScale, get_surface, evaluate_color
+
+layout(location = 0) out vec4 o_Color;
+
+void main() {
+    //TODO: move most of the evaluation to the vertex shader
+    o_Color = evaluate_color(v_Type, v_TexCoord.xy, v_TexCoord.z, 1.0);
+}
+#endif //FS

res/shader/terrain/ray.glsl

@@ -1,4 +1,4 @@
-//!include vs:globals.inc fs:globals.inc fs:surface.inc fs:color.inc
+//!include vs:globals.inc fs:globals.inc fs:terrain/locals.inc fs:surface.inc fs:color.inc
 
 #ifdef SHADER_VS
 
@@ -13,11 +13,6 @@ void main() {
 #ifdef SHADER_FS
 //imported: Surface, u_TextureScale, get_surface, evaluate_color
 
-layout(set = 1, binding = 1) uniform c_Locals {
-    uvec4 u_ScreenSize;      // XY = size
-    uvec4 u_Params;
-};
-
 const float
     c_ReflectionVariance = 0.5,
     c_ReflectionPower = 0.2;

res/shader/terrain/ray_mip.glsl

@@ -1,4 +1,4 @@
-//!include vs:globals.inc fs:globals.inc fs:surface.inc fs:color.inc
+//!include vs:globals.inc fs:globals.inc fs:terrain/locals.inc fs:surface.inc fs:color.inc
 
 #ifdef SHADER_VS
 
@@ -13,11 +13,6 @@ void main() {
 #ifdef SHADER_FS
 //imported: Surface, u_TextureScale, get_lod_height, get_surface, evaluate_color
 
-layout(set = 1, binding = 1) uniform Locals {
-    uvec4 u_ScreenSize; // XY = size
-    uvec4 u_Params; // X = max mipmap level, Y = max iterations
-};
-
 #define TERRAIN_WATER   0U
 
 const float c_Step = 0.6;

res/shader/terrain/scatter.glsl

@@ -1,46 +1,11 @@
-//!include cs:globals.inc cs:surface.inc cs:color.inc
+//!include cs:globals.inc cs:terrain/locals.inc cs:surface.inc cs:color.inc
 
 #ifdef SHADER_CS
 //imported: Surface, get_surface, evaluate_color_id
 
-layout(set = 1, binding = 1) uniform c_Locals {
-    uvec4 u_ScreenSize;      // XY = size
-};
 layout(set = 2, binding = 0, std430) buffer Storage {
     uint w_Data[];
 };
-layout(set = 2, binding = 1) uniform c_Scatter {
-    vec2 u_CamOrigin;
-    vec2 u_CamDir;
-    vec2 u_RangeY;
-    vec2 u_RangeX;
-};
-
-
-vec2 generate_pos() {
-    vec2 screen_coord = vec2(gl_GlobalInvocationID.xy) /
-        vec2(gl_NumWorkGroups.xy * gl_WorkGroupSize.xy - vec2(1));
-
-    float y;
-    if (true) {
-        float y_sqrt = mix(
-            sqrt(abs(u_RangeY.x)) * sign(u_RangeY.x),
-            sqrt(abs(u_RangeY.y)) * sign(u_RangeY.y),
-            screen_coord.y
-        );
-        y = y_sqrt * y_sqrt * sign(y_sqrt);
-    } else {
-        y = mix(u_RangeY.x, u_RangeY.y, screen_coord.y);
-    }
-
-    float x_limit = mix(
-        u_RangeX.x, u_RangeX.y,
-        (y - u_RangeY.x) / (u_RangeY.y - u_RangeY.x)
-    );
-    float x = mix(-x_limit, x_limit, screen_coord.x);
-
-    return u_CamOrigin + u_CamDir * y + vec2(u_CamDir.y, -u_CamDir.x) * x;
-}
 
 bool is_visible(vec4 p) {
     return p.w > 0.0 && p.z >= 0.0 &&
@@ -62,7 +27,10 @@ void add_voxel(vec2 pos, float altitude, uint type, float lit_factor) {
 }
 
 void main() {
-    vec2 pos = generate_pos();
+    vec2 source_coord = vec2(gl_GlobalInvocationID.xy) /
+        vec2(gl_NumWorkGroups.xy * gl_WorkGroupSize.xy - vec2(1));
+    vec2 pos = generate_scatter_pos(source_coord);
+
     Surface suf = get_surface(pos);
     float base = 0.0;
     float t = float(gl_GlobalInvocationID.z) / float(gl_NumWorkGroups.z * gl_WorkGroupSize.z);

res/shader/terrain/slice.glsl

@@ -7,7 +7,7 @@ layout(location = 0) varying vec4 v_Pos;
 layout(location = 0) attribute ivec4 a_Pos;
 
 void main() {
-    v_Pos = vec4(ivec4(a_Pos.xy * u_TextureScale.xy, 255 - gl_InstanceIndex, 1));
+    v_Pos = vec4(a_Pos.xy * u_TextureScale.xy, u_TextureScale.z - float(gl_InstanceIndex + 1), 1.0);
     gl_Position = u_ViewProj * v_Pos;
 }
 #endif //VS

src/config/settings.rs

@@ -116,6 +116,10 @@ pub enum Terrain {
         screen_space: bool,
     },
     Sliced,
+    Painted {
+        density: f32,
+        min_divisor: f32,
+    },
     Scattered {
         density: [u32; 3],
     },