Add low level graphics render passes and refactor painter draw methods

Add low level graphics render passes and refactor painter draw methods.
This change is needed because there's a need to be able to leverage
the painter draw methods in more elaborate drawing systems when doing
multiple passes over the items and rendering to various different
render targets/buffers. This change splits some rendering state into
"render pass"  objects which are then responsible for setting up the
right device state for writing to color/depth/stencil buffers. Doing
this also simplifies the painter implementation since it no longer
needs to implement different draws such as mask+cover itself but the
caller can create such a setup easily. The legacy functionality for
the simplest draw is kept for backwards compatibility by adding some
default render pass implementations and using those implicitly.

The render pass object is now also added to the environment arguments
passed to the material and drawable when applying program/device state.
This allows the materials and drawables to provide alternative ways
for performing some render pass, such as using simpler shaders when
doing a stencil pass and now actual RGB computation is needed.

CMakeLists.txt

@@ -170,6 +170,7 @@ add_library(GfxLib
     graphics/drawing.cpp
     graphics/drawable.cpp
     graphics/material.cpp
+    graphics/renderpass.cpp
     graphics/image.cpp
     graphics/device.cpp
     graphics/opengl_es2_device.cpp
@@ -200,6 +201,7 @@ add_library(GfxLibTesting
     graphics/drawing.cpp
     graphics/drawable.cpp
     graphics/material.cpp
+    graphics/renderpass.cpp
     graphics/image.cpp
     graphics/device.cpp
     graphics/opengl_es2_device.cpp
@@ -583,6 +585,7 @@ install(TARGETS audio_test DESTINATION "${CMAKE_CURRENT_LIST_DIR}/audio/test/")
 add_executable(graphics_test
     graphics/bitmap.cpp
     graphics/material.cpp
+    graphics/renderpass.cpp
     graphics/drawable.cpp
     graphics/drawing.cpp
     graphics/device.cpp

engine/renderer.cpp

@@ -30,6 +30,7 @@
 #include "graphics/material.h"
 #include "graphics/painter.h"
 #include "graphics/transform.h"
+#include "graphics/renderpass.h"
 #include "engine/classlib.h"
 #include "game/entity.h"
 #include "game/scene.h"
@@ -573,15 +574,15 @@ void Renderer::CreateDrawResources(PaintNode& paint_node)
     {
         const auto& material = item->GetMaterialId();
         const auto& drawable = item->GetDrawableId();
-        if (item->GetRenderPass() == RenderPass::Draw && paint_node.item_material_id != material)
+        if (paint_node.item_material_id != material)
         {
             paint_node.item_material.reset();
             paint_node.item_material_id = material;
             auto klass = mClassLib->FindMaterialClassById(material);
             if (klass)
                 paint_node.item_material = gfx::CreateMaterialInstance(klass);
             if (!paint_node.item_material)
-                WARN("No such material class '%1' found for '%2/%3')", material, entity.GetName(), node.GetName());
+                WARN("No such material class found. [material='%1', entity='%2', node='%3']", material, entity.GetName(), node.GetName());
         }
         if (paint_node.item_drawable_id != drawable)
         {
@@ -592,7 +593,7 @@ void Renderer::CreateDrawResources(PaintNode& paint_node)
             if (klass)
                 paint_node.item_drawable = gfx::CreateDrawableInstance(klass);
             if (!paint_node.item_drawable)
-                WARN("No such drawable class '%1' found for '%2/%3'", drawable, entity.GetName(), node.GetName());
+                WARN("No such drawable class found. [drawable='%1', entity='%2, node='%3']", drawable, entity.GetName(), node.GetName());
             if (paint_node.item_drawable)
             {
                 gfx::Transform transform;
@@ -744,7 +745,7 @@ void Renderer::DrawPackets(gfx::Painter& painter, std::vector<DrawPacket>& packe
 
     struct Layer {
         std::vector<gfx::Painter::DrawShape> draw_list;
-        std::vector<gfx::Painter::MaskShape> mask_list;
+        std::vector<gfx::Painter::DrawShape> mask_list;
     };
     // Each entity in the scene is assigned to a scene/entity layer and each
     // entity node within an entity is assigned to an entity layer.
@@ -774,25 +775,35 @@ void Renderer::DrawPackets(gfx::Painter& painter, std::vector<DrawPacket>& packe
         {
             gfx::Painter::DrawShape shape;
             shape.transform = &packet.transform;
-            shape.drawable = packet.drawable.get();
-            shape.material = packet.material.get();
+            shape.drawable  = packet.drawable.get();
+            shape.material  = packet.material.get();
             entity_layer.draw_list.push_back(shape);
         }
         else if (packet.pass == RenderPass::Mask)
         {
-            gfx::Painter::MaskShape shape;
+            gfx::Painter::DrawShape shape;
             shape.transform = &packet.transform;
-            shape.drawable = packet.drawable.get();
+            shape.drawable  = packet.drawable.get();
+            shape.material  = packet.material.get();
             entity_layer.mask_list.push_back(shape);
         }
     }
     for (const auto& scene_layer : layers)
     {
         for (const auto& entity_layer : scene_layer)
         {
-            entity_layer.mask_list.empty()
-                ? painter.Draw(entity_layer.draw_list)
-                : painter.Draw(entity_layer.draw_list, entity_layer.mask_list);
+            if (!entity_layer.mask_list.empty())
+            {
+                const gfx::detail::StencilMaskPass mask(1, 0);
+                const gfx::detail::StencilTestColorWritePass cover(1);
+                painter.Draw(entity_layer.mask_list, mask);
+                painter.Draw(entity_layer.draw_list, cover);
+            }
+            else if (!entity_layer.draw_list.empty())
+            {
+                const gfx::detail::GenericRenderPass pass;
+                painter.Draw(entity_layer.draw_list, pass);
+            }
         }
     }
 }

graphics/drawable.h

@@ -46,6 +46,7 @@ namespace gfx
     class Shader;
     class Geometry;
     class Program;
+    class RenderPass;
 
     // DrawableClass defines a new type of drawable.
      class DrawableClass
@@ -88,6 +89,7 @@ namespace gfx
              Points
          };
          struct Environment {
+             const RenderPass* render_pass = nullptr;
              // true if running in an "editor mode", which means that even
              // content marked static might have changed and should be checked
              // in case it has been modified and should be re-uploaded.

graphics/drawing.cpp

@@ -28,6 +28,7 @@
 #include "graphics/drawable.h"
 #include "graphics/transform.h"
 #include "graphics/text.h"
+#include "graphics/renderpass.h"
 
 namespace {
 gfx::MaterialClassInst MakeMaterial(const gfx::Color4f& color)
@@ -194,7 +195,11 @@ void DrawShapeOutline(Painter& painter, const FRect& rect, const Drawable& shape
     const auto mask_height = height - 2 * line_width;
     mask_transform.Resize(mask_width, mask_height);
     mask_transform.Translate(x + line_width, y + line_width);
-    painter.Draw(shape, outline_transform, shape, mask_transform, material);
+
+    detail::StencilMaskPass mask(1, 0);
+    detail::StencilTestColorWritePass cover(1);
+    painter.Draw(shape, mask_transform, material, mask);
+    painter.Draw(shape, outline_transform, material, cover);
 }
 
 void DrawLine(Painter& painter, const FPoint& a, const FPoint& b, const Color4f& color, float line_width)

graphics/material.h

@@ -48,6 +48,7 @@ namespace gfx
 {
     class Device;
     class Shader;
+    class RenderPass;
 
     // Interface for acquiring texture data. Possible implementations
     // might load the data from a file or generate it on the fly.
@@ -1459,6 +1460,7 @@ namespace gfx
         virtual ~Material() = default;
 
         struct Environment {
+            const RenderPass* render_pass = nullptr;
             // true if running in an "editing mode", which means that even
             // content marked static might have changed and should be checked
             // in case it has been modified and should be re-uploaded.

graphics/opengl_es2_device.cpp

@@ -819,9 +819,8 @@ class OpenGLES2GraphicsDevice : public Device
         {
             GLenum depth_test;
             if (state.depth_test == State::DepthTest::LessOrEQual)
-                depth_test = GL_LEQUAL;
+                GL_CALL(glDepthFunc(depth_test));
             else BUG("Unknown GL depth test mode.");
-            GL_CALL(glDepthFunc(depth_test));
         }
 
         if (state.bWriteColor) {