renderer: introduce text rendering

1 files changed, 95 insertions, 28 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;
+    }
+}
+