Minimal working version

examples/basic.cpp

@@ -1,8 +1,21 @@
 #include <sprstk/sprstk.h>
 
+namespace
+{
+
+void update(sprstk* instance, float dt, void* userdata)
+{
+  for (int i = 0; i < 10; i += 2)
+  {
+    sprstk_put(instance, i, 0);
+  }
+}
+
+}
+
 int main()
 {
-  sprstk* instance = sprstk_new({.update = [](sprstk*, float, void*) {}}, nullptr);
+  sprstk* instance = sprstk_new({.update = update}, nullptr);
 
   sprstk_run(instance);
 

include/sprstk/sprstk.h

@@ -24,6 +24,9 @@ void sprstk_del(sprstk* instance);
 void sprstk_run(sprstk* instance);
 void sprstk_stop(sprstk* instance);
 
+void sprstk_put(sprstk* instance, unsigned int x, unsigned int y);
+void sprstk_putz(sprstk* instance, unsigned int x, unsigned int y, unsigned int z_offset);
+
 #ifdef __cplusplus
 }
 #endif

src/sprstk.cpp

@@ -10,32 +10,60 @@ const char* MESH_SHADER_CODE = R"(
 
 #extension GL_NV_mesh_shader : require
 
-layout(local_size_x = 1) in;
-layout(triangles, max_vertices = 3, max_primitives = 1) out;
+layout (local_size_x = 32) in;
+layout (triangles, max_vertices = 128, max_primitives = 64) out;
 
 layout (location = 0) out PerVertexData
 {
   vec4 color;
 } v_out[];
 
-const vec3 vertices[3] = {vec3(-1, -1, 0), vec3(0, 1, 0), vec3(1, -1, 0)};
-const vec3 colors[3] = {vec3(1, 0, 0), vec3(0, 1, 0), vec3(0, 0, 1)};
+layout (location = 1) uniform vec3 screen_size_and_pixel_scale;
+
+struct TileInfo
+{
+  uint position;
+};
+
+layout (std430, binding = 0) restrict readonly buffer TileInfos
+{
+  TileInfo[] tile_infos;
+};
+
+const uint indices[6] = { 0, 1, 2, 2, 1, 3 };
 
 void main()
 {
-  gl_MeshVerticesNV[0].gl_Position = vec4(vertices[0], 1);
-  gl_MeshVerticesNV[1].gl_Position = vec4(vertices[1], 1);
-  gl_MeshVerticesNV[2].gl_Position = vec4(vertices[2], 1);
+  TileInfo info = tile_infos[gl_WorkGroupID.x];
+  uint position_x = bitfieldExtract(info.position, 0, 13);
+  uint position_y = bitfieldExtract(info.position, 13, 13);
+  vec2 stack_position = vec2(position_x, position_y);
 
-  v_out[0].color = vec4(colors[0], 1);
-  v_out[1].color = vec4(colors[1], 1);
-  v_out[2].color = vec4(colors[2], 1);
+  vec2 positions[4] = { vec2(0, 0), vec2(1, 0), vec2(0, 1), vec2(1, 1) };
+  for (uint i = 0; i < 4; i++)
+  {
+    positions[i] += stack_position;
+    positions[i] *= screen_size_and_pixel_scale.zz;
+    positions[i] /= screen_size_and_pixel_scale.xy;
+  }
 
-  gl_PrimitiveIndicesNV[0] = 0;
-  gl_PrimitiveIndicesNV[1] = 1;
-  gl_PrimitiveIndicesNV[2] = 2;
+  uint z_offset = bitfieldExtract(info.position, 26, 6);
 
-  gl_PrimitiveCountNV = 1;
+  for (uint i = 4 * gl_LocalInvocationID.x; i < 4 * gl_LocalInvocationID.x + 4; i++)
+  {
+    vec4 position = vec4(positions[i % 4], float(4 * gl_LocalInvocationID.x + z_offset) / 128, 1);
+    position.y += 8 * position.z / screen_size_and_pixel_scale.z;
+    gl_MeshVerticesNV[i].gl_Position = position;
+
+    v_out[i].color = vec4(1, 1, 1, 0.1);
+  }
+
+  for (uint i = 6 * gl_LocalInvocationID.x; i < 6 * gl_LocalInvocationID.x + 6; i++)
+  {
+    gl_PrimitiveIndicesNV[i] = 4 * gl_LocalInvocationID.x + indices[i % 6];
+  }
+
+  gl_PrimitiveCountNV = 64;
 }
 )";
 
@@ -55,6 +83,11 @@ void main()
 }
 )";
 
+struct TileInfo
+{
+  uint32_t position;
+};
+
 class application_error : public std::runtime_error
 {
 public:
@@ -105,15 +138,19 @@ public:
           int width, height;
           SDL_GetWindowSizeInPixels(sdl.window, &width, &height);
           glViewport(0, 0, width, height);
+          glProgramUniform3f(gl.program, 1, width, height, 32);
         }
       }
 
       uint64_t current_ticks = SDL_GetTicks();
       float dt = (prev_ticks - current_ticks) / 1000.0f;
 
+      gl.tile_count = 0;
       callbacks.update(this, dt, userdata);
 
-      glDrawMeshTasksNV(0, 1);
+      glClearColor(0, 0, 0, 1);
+      glClear(GL_COLOR_BUFFER_BIT);
+      glDrawMeshTasksNV(0, gl.tile_count);
 
       SDL_GL_SwapWindow(sdl.window);
     }
@@ -126,6 +163,16 @@ public:
     should_stop = true;
   }
 
+  void put(unsigned int x, unsigned int y, unsigned int z_offset = 0)
+  {
+    x &= 0b0001111111111111;
+    y &= 0b0001111111111111;
+    y <<= 13;
+    z_offset &= 0b111111;
+    z_offset <<= 26;
+    gl.tile_buffer_map[gl.tile_count++] = { x | y | z_offset };
+  }
+
 private:
   sprstk_callbacks callbacks;
   void* userdata;
@@ -141,6 +188,9 @@ private:
   struct
   {
     unsigned int program;
+    unsigned int tile_buffer;
+    TileInfo* tile_buffer_map;
+    unsigned int tile_count;
   } gl;
 
   void init_sdl()
@@ -155,6 +205,7 @@ private:
     SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
     SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
     SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_DEBUG_FLAG);
 
     sdl.window = SDL_CreateWindow("sprstk", 640, 480, SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
     if (!sdl.window)
@@ -186,6 +237,14 @@ private:
       throw application_error("Mesh shaders not supported");
     }
 
+    glEnable(GL_BLEND);
+    glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ZERO);
+
+    glDebugMessageCallback([](GLenum source, GLenum type, GLuint id, GLenum severity, GLsizei length, const GLchar* message, const void* userdata)
+    {
+      SDL_LogWarn(SDL_LOG_CATEGORY_APPLICATION, "%s", message);
+    }, nullptr);
+
     int success;
     char info_log[512];
 
@@ -229,10 +288,24 @@ private:
     }
 
     glUseProgram(gl.program);
+
+    int width, height;
+    SDL_GetWindowSizeInPixels(sdl.window, &width, &height);
+    glViewport(0, 0, width, height);
+    glProgramUniform3f(gl.program, 1, width, height, 32);
+
+    glGenBuffers(1, &gl.tile_buffer);
+    glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, gl.tile_buffer);
+    glNamedBufferStorage(gl.tile_buffer, sizeof(TileInfo) * (1 << 26), nullptr, GL_MAP_WRITE_BIT | GL_MAP_COHERENT_BIT | GL_MAP_PERSISTENT_BIT);
+
+    gl.tile_count = 0;
+    gl.tile_buffer_map = (TileInfo*)glMapNamedBufferRange(gl.tile_buffer, 0, sizeof(TileInfo) * (1 << 26), GL_MAP_WRITE_BIT | GL_MAP_COHERENT_BIT);
   }
 
   void destroy_gl()
   {
+    glDeleteProgram(gl.program);
+    glDeleteBuffers(1, &gl.tile_buffer);
     SDL_GL_DestroyContext(sdl.context);
   }
 };
@@ -281,4 +354,14 @@ void sprstk_stop(sprstk* instance)
   instance->stop();
 }
 
+void sprstk_put(sprstk* instance, unsigned int x, unsigned int y)
+{
+  instance->put(x, y);
+}
+
+void sprstk_putz(sprstk* instance, unsigned int x, unsigned int y, unsigned int z_offset)
+{
+  instance->put(x, y, z_offset);
+}
+
 }