renderer: introduce text rendering

4 files changed, 155 insertions, 51 deletions

diff --git a/src/renderer/RSoftwareBackend.cpp b/src/renderer/RSoftwareBackend.cpp
index 4d78ec7..d05cee7 100644
--- a/src/renderer/RSoftwareBackend.cpp
+++ b/src/renderer/RSoftwareBackend.cpp
@@ -1,3 +1,4 @@
+#include "imgui.h"
 #include <renderer/RSoftwareBackend.hpp>
 
 #include <SDL3/SDL_video.h>
@@ -8,9 +9,8 @@
 #include <cstdio>
 
 
-RSoftwareBackend::RSoftwareBackend(SDL_Window* window, Renderer& renderer)
-    : m_window {window}
-    , m_renderer {renderer}
+RSoftwareBackend::RSoftwareBackend(Renderer& renderer)
+    : m_renderer {renderer}
 {
     m_canvas.rshift = 0;
     m_canvas.gshift = 8;
@@ -53,21 +53,7 @@ RSoftwareBackend::Draw()
     SortRenderEntities();
 
 
-    REntity_Rectangle clear_rect = {
-        REntityType_Rectangle,
-        {0, 0, (float)(m_canvas.w-1), (float)(m_canvas.h-1)},
-        0.0f,
-        m_renderer.m_clear_color
-    };
-    DrawRectangle(clear_rect);
-
-
-    float z = -1;
     for (RSortEntry sort_entry : m_renderer.m_sort_entries) {
-        if (sort_entry.z >= z) {
-            z = sort_entry.z;
-        }
-
         REntity& entity = m_renderer.m_render_entities[sort_entry.entity_index];
         switch (entity.type) {
         case REntityType_Rectangle: {
@@ -78,6 +64,13 @@ RSoftwareBackend::Draw()
             DrawAlphaBitmap(entity.bitmap);
         } break;
 
+        case REntityType_Text: {
+            DrawText(entity.text);
+        }; break;
+
+        case REntityType_Circle: {
+        }; break;
+
         default:;
         }
     }
@@ -147,10 +140,10 @@ RSoftwareBackend::DrawRectangle(REntity_Rectangle& entity)
 void
 RSoftwareBackend::DrawAlphaBitmap(REntity_AlphaBitmap& entity)
 {
-    int32_t x0 = (int32_t)entity.pos.x;
-    int32_t y0 = (int32_t)entity.pos.y;
-    int32_t x1 = (int32_t)entity.pos.x + entity.bitmap.w - 1;
-    int32_t y1 = (int32_t)entity.pos.y + entity.bitmap.h - 1;
+    int32_t x0 = m_renderer.WorldXToScreenX(entity.pos.x);
+    int32_t y0 = m_renderer.WorldYToScreenY(entity.pos.y);
+    int32_t x1 = x0 + entity.bitmap.w - 1;
+    int32_t y1 = y0 + entity.bitmap.h - 1;
 
     int32_t cut_left = 0;
     int32_t cut_bot = 0;
@@ -171,10 +164,6 @@ RSoftwareBackend::DrawAlphaBitmap(REntity_AlphaBitmap& entity)
     }
 
 
-    uint32_t rshift = m_canvas.rshift;
-    uint32_t gshift = m_canvas.gshift;
-    uint32_t bshift = m_canvas.bshift;
-
     uint8_t* alpha_row = (uint8_t*)entity.bitmap.pixels.get() + (-cut_bot * entity.bitmap.w) + (-cut_left);
     uint32_t* rgba_row = m_canvas.pixels + y0 * m_canvas.w + x0;
     for (int32_t y = y0; y <= y1; y++) {
@@ -193,9 +182,9 @@ RSoftwareBackend::DrawAlphaBitmap(REntity_AlphaBitmap& entity)
             float g1 = entity.color.g * alphaf;
             float b1 = entity.color.b * alphaf;
 
-            uint32_t r2 = uint32_t(r1 * 255.0f) << rshift;
-            uint32_t g2 = uint32_t(g1 * 255.0f) << gshift;
-            uint32_t b2 = uint32_t(b1 * 255.0f) << bshift;
+            uint32_t r2 = uint32_t(r1 * 255.0f) << m_canvas.rshift;
+            uint32_t g2 = uint32_t(g1 * 255.0f) << m_canvas.gshift;
+            uint32_t b2 = uint32_t(b1 * 255.0f) << m_canvas.bshift;
 
             uint32_t rgba_result = r2 | g2 | b2;
             *rgba = rgba_result;
@@ -209,3 +198,81 @@ RSoftwareBackend::DrawAlphaBitmap(REntity_AlphaBitmap& entity)
     }
 }
 
+void
+RSoftwareBackend::DrawText(REntity_Text& entity)
+{
+    int32_t xscreen = m_renderer.WorldXToScreenX(entity.pos.x);
+    int32_t yscreen = m_renderer.WorldYToScreenY(entity.pos.y);
+    for (char32_t ch : entity.text) {
+        Glyph& glyph = entity.font.GetGlyph(ch);
+
+        int32_t x = xscreen + glyph.xoff;
+        int32_t y = yscreen + glyph.yoff;
+        DrawTextGlyph(glyph, entity.color, x, y);
+
+        xscreen += glyph.xadvance;
+    }
+}
+
+void
+RSoftwareBackend::DrawTextGlyph(Glyph& glyph, Color color, int32_t xscreen, int32_t yscreen)
+{
+    int32_t x0 = xscreen;
+    int32_t y0 = yscreen;
+    int32_t x1 = x0 + glyph.bitmap.w - 1;
+    int32_t y1 = y0 + glyph.bitmap.h - 1;
+
+    int32_t cut_left = 0;
+    int32_t cut_bot = 0;
+
+    if (x0 < 0) {
+        cut_left = x0;
+        x0 = 0;
+    }
+    if (y0 < 0) {
+        cut_bot = y0;
+        y0 = 0;
+    }
+    if (x1 >= m_canvas.w) {
+        x1 = m_canvas.w - 1;
+    }
+    if (y1 >= m_canvas.h) {
+        y1 = m_canvas.h - 1;
+    }
+
+
+    uint8_t* alpha_row = (uint8_t*)glyph.bitmap.pixels.get() + (-cut_bot * glyph.bitmap.w) + (-cut_left);
+    uint32_t* rgba_row = m_canvas.pixels + y0 * m_canvas.w + x0;
+
+    for (int32_t y = y0; y <= y1; y++) {
+        uint8_t* alpha = alpha_row;
+        uint32_t* rgba = rgba_row;
+        for (int32_t x = x0; x <= x1; x++) {
+            if (*alpha == 0) {
+                alpha++;
+                rgba++;
+                continue;
+            }
+
+            float alphaf = *alpha / 255.0f;
+
+            float r1 = color.r * alphaf;
+            float g1 = color.g * alphaf;
+            float b1 = color.b * alphaf;
+
+            uint32_t r2 = uint32_t(r1 * 255.0f) << m_canvas.rshift;
+            uint32_t g2 = uint32_t(g1 * 255.0f) << m_canvas.gshift;
+            uint32_t b2 = uint32_t(b1 * 255.0f) << m_canvas.bshift;
+
+            uint32_t rgba_result = r2 | g2 | b2;
+            *rgba = rgba_result;
+
+            alpha++;
+            rgba++;
+        }
+
+        alpha_row += glyph.bitmap.w;
+        rgba_row += m_canvas.w;
+    }
+}
+
diff --git a/src/renderer/RSoftwareBackend.hpp b/src/renderer/RSoftwareBackend.hpp
index 89d6a52..3e5e17d 100644
--- a/src/renderer/RSoftwareBackend.hpp
+++ b/src/renderer/RSoftwareBackend.hpp
@@ -16,11 +16,19 @@ public:
         uint32_t* pixels;
     };
 
+    struct DestRect {
+        int32_t x0;
+        int32_t y0;
+        int32_t x1;
+        int32_t y1;
+    };
+
 
 public:
-    RSoftwareBackend(SDL_Window* window, Renderer& renderer);
+    RSoftwareBackend(Renderer& renderer);
 
     void Draw();
+    void Clear(Color color);
 
 
 private:
@@ -29,10 +37,11 @@ private:
 
     void DrawRectangle(REntity_Rectangle& entity);
     void DrawAlphaBitmap(REntity_AlphaBitmap& entity);
+    void DrawText(REntity_Text& entity);
+    void DrawTextGlyph(Glyph& glyph, Color color, int32_t xscreen, int32_t yscreen);
 
 
 private:
-    SDL_Window* m_window{};
     Renderer& m_renderer;
 
     uint32_t m_gltexture_id{};
diff --git a/src/renderer/Renderer.cpp b/src/renderer/Renderer.cpp
index 4e449ba..956c488 100644
--- a/src/renderer/Renderer.cpp
+++ b/src/renderer/Renderer.cpp
@@ -13,16 +13,10 @@ Renderer g_renderer;
 void
 Renderer::Init(SDL_Window* window)
 {
+    m_window = window;
     m_render_entities.reserve(1024);
     m_sort_entries.reserve(1024);
-
-    m_backend = std::make_unique<RSoftwareBackend>(window, *this);
-}
-
-void
-Renderer::Draw()
-{
-    m_backend->Draw();
+    m_backend = std::make_unique<RSoftwareBackend>(*this);
 }
 
 void
@@ -30,12 +24,16 @@ Renderer::Reset()
 {
     m_render_entities.clear();
     m_sort_entries.clear();
-    m_render_entities.reserve(1024);
-    m_sort_entries.reserve(1024);
     SetCameraSize(0.0f, 0.0f);
 }
 
 void
+Renderer::Draw()
+{
+    m_backend->Draw();
+}
+
+void
 Renderer::SetScreenSize(int32_t w, int32_t h)
 {
     m_screen_w = w;
@@ -66,7 +64,13 @@ Renderer::WorldYToScreenY(float world_y)
 void
 Renderer::Clear(Color color)
 {
-    m_clear_color = color;
+    Rectangle rect = {
+        0.0f,
+        0.0f,
+        m_camera_w,
+        m_camera_h
+    };
+    PushRectangle(rect, color, -1.0f);
 }
 
 void
@@ -74,37 +78,48 @@ Renderer::PushAlphaBitmap(AlphaBitmap& bitmap, V3F32 pos, Color color)
 {
     m_render_entities.emplace_back(REntity{.bitmap{
             REntityType_AlphaBitmap,
-            pos,
             bitmap,
+            pos,
             color
     }});
     m_sort_entries.emplace_back(pos.z, m_render_entities.size()-1);
 }
 
 void
-Renderer::PushRectangle(Rectangle rect, float z, Color color)
+Renderer::PushRectangle(Rectangle rect, Color color, float z)
 {
     m_render_entities.emplace_back(REntity{.rect{
             REntityType_Rectangle,
             rect,
-            z,
             color
     }});
     m_sort_entries.emplace_back(z, m_render_entities.size()-1);
 }
 
 void
-Renderer::PushCircle(Circle circle, float z, Color color)
+Renderer::PushCircle(Circle circle, Color color, float z)
 {
     m_render_entities.emplace_back(REntity{.circle{
             REntityType_Circle,
             circle,
-            z,
             color
     }});
     m_sort_entries.emplace_back(z, m_render_entities.size()-1);
 }
 
+void
+Renderer::PushText(std::u32string& text, Font& font, V3F32 pos, Color color)
+{
+    m_render_entities.emplace_back(REntity{.text{
+            REntityType_Text,
+            text,
+            font,
+            pos,
+            color
+    }});
+    m_sort_entries.emplace_back(pos.z, m_render_entities.size()-1);
+}
+
 
 /* temporary helper functions (from old RGroup api) */
 
diff --git a/src/renderer/Renderer.hpp b/src/renderer/Renderer.hpp
index b825681..515e1da 100644
--- a/src/renderer/Renderer.hpp
+++ b/src/renderer/Renderer.hpp
@@ -22,34 +22,44 @@ enum REntityType : int32_t {
     REntityType_Rectangle,
     REntityType_AlphaBitmap,
     REntityType_Circle,
+    REntityType_Text,
 };
 
+
 struct REntity_AlphaBitmap {
     REntityType type;
-    V3F32 pos;
     AlphaBitmap& bitmap;
+    V3F32 pos;
     Color color;
 };
 
 struct REntity_Rectangle {
     REntityType type;
     Rectangle rect;
-    float z;
     Color color;
 };
 
 struct REntity_Circle {
     REntityType type;
     Circle circle;
-    float z;
     Color color;
 };
 
+struct REntity_Text {
+    REntityType type;
+    std::u32string& text;
+    Font& font;
+    V3F32 pos;
+    Color color;
+};
+
+
 union REntity {
     REntityType type;
     REntity_AlphaBitmap bitmap;
     REntity_Rectangle rect;
     REntity_Circle circle;
+    REntity_Text text;
 };
 
 struct RSortEntry {
@@ -69,9 +79,10 @@ public:
     void Reset();
 
     void Clear(Color color);
-    void PushRectangle(Rectangle rect, float z, Color color);
     void PushAlphaBitmap(AlphaBitmap& bitmap, V3F32 pos, Color color);
-    void PushCircle(Circle circle, float z, Color color);
+    void PushRectangle(Rectangle rect, Color color, float z);
+    void PushCircle(Circle circle, Color color, float z);
+    void PushText(std::u32string& text, Font& font, V3F32 pos, Color color);
 
 
     /* helper functions */
@@ -98,6 +109,8 @@ public:
 
 
 public:
+    SDL_Window* m_window;
+
     int32_t m_screen_w;
     int32_t m_screen_h;