From d7c15660e5d73b950b81625821184688af28ed6f Mon Sep 17 00:00:00 2001
From: Patrick Wuttke <mewin@mewin.de>
Date: Tue, 17 Sep 2024 17:37:29 +0200
Subject: [PATCH] Colorful text.

---
 private/sdl_gpu_test/6_ui/ui/ui_renderer.cpp | 74 +++++++++++++++-----
 private/sdl_gpu_test/6_ui/ui/ui_renderer.hpp |  3 +
 2 files changed, 61 insertions(+), 16 deletions(-)

diff --git a/private/sdl_gpu_test/6_ui/ui/ui_renderer.cpp b/private/sdl_gpu_test/6_ui/ui/ui_renderer.cpp
index 3316a81..431198f 100644
--- a/private/sdl_gpu_test/6_ui/ui/ui_renderer.cpp
+++ b/private/sdl_gpu_test/6_ui/ui/ui_renderer.cpp
@@ -1,6 +1,8 @@
 
 #include "./ui_renderer.hpp"
 
+#include <mijin/util/string.hpp>
+
 namespace sdl_gpu_test::inline app6
 {
 namespace
@@ -94,7 +96,7 @@ void UIRenderer::init(Application& application)
     drawText({
         .x = 100,
         .y = 100,
-        .text = "Test-Text!\nSecond line?"
+        .text = "Test-Text!\nSecond $f00line$fff?"
     });
 
     // create UI vertex buffer
@@ -145,23 +147,58 @@ void UIRenderer::render(const UIRendererRenderArgs& args)
 
 void UIRenderer::drawText(const DrawTextArgs& args)
 {
+    glm::vec4 color = args.color;
     unsigned posX = args.x;
     unsigned posY = args.y;
-    for (const char chr : args.text)
+
+    for (std::size_t pos = 0; pos < args.text.size(); ++pos)
     {
+        char chr = args.text[pos];
         switch (chr)
         {
-            case '\n':
-                posX = args.x;
-                posY += mFontMap.lineHeight;
+        case '\n':
+            posX = args.x;
+            posY += mFontMap.lineHeight;
+            break;
+        case '$':
+            ++pos;
+            if (pos >= args.text.size())
+            {
                 break;
-            default:
-                posX += drawChar({
-                    .x = posX,
-                    .y = posY,
-                    .chr = chr
-                });
+            }
+            chr = args.text[pos];
+            if (pos < args.text.size() - 2
+                && mijin::isHexadecimalChar(chr)
+                && mijin::isHexadecimalChar(args.text[pos + 1])
+                && mijin::isHexadecimalChar(args.text[pos + 2]))
+            {
+                unsigned num = 0;
+                (void) mijin::toNumber(args.text.substr(pos, 3), num, 16);
+                const std::uint8_t red = static_cast<std::uint8_t>(num >> 8);
+                const std::uint8_t green = static_cast<std::uint8_t>((num >> 4) & 0xF);
+                const std::uint8_t blue = static_cast<std::uint8_t>(num & 0xF);
+                color.r = static_cast<float>(red) / 15.f;
+                color.g = static_cast<float>(green) / 15.f;
+                color.b = static_cast<float>(blue) / 15.f;
+                pos += 2;
+            }
+            break;
+        case '\\':
+            ++pos;
+            if (pos >= args.text.size())
+            {
                 break;
+            }
+            chr = args.text[pos];
+            [[fallthrough]];
+        default:
+            posX += drawChar({
+                .x = posX,
+                .y = posY,
+                .chr = chr,
+                .color = color
+            });
+            break;
         }
     }
 }
@@ -174,7 +211,8 @@ unsigned UIRenderer::drawChar(const DrawCharArgs& args)
         .topLeft = topLeft,
         .bottomRight = {topLeft.x + static_cast<float>(entry.width), topLeft.y + static_cast<float>(entry.height)},
         .uvTopLeft = {entry.uvX, entry.uvY},
-        .uvBottomRight = {entry.uvX + entry.uvWidth, entry.uvY + entry.uvHeight}
+        .uvBottomRight = {entry.uvX + entry.uvWidth, entry.uvY + entry.uvHeight},
+        .color = args.color
     });
 
     return entry.xAdvance;
@@ -184,19 +222,23 @@ void UIRenderer::drawQuadInternal(const DrawQuadInternalArgs& args)
 {
     const UIVertex topLeft = {
         .pos = args.topLeft,
-        .texcoord = args.uvTopLeft
+        .texcoord = args.uvTopLeft,
+        .color = args.color
     };
     const UIVertex bottomRight = {
         .pos = args.bottomRight,
-        .texcoord = args.uvBottomRight
+        .texcoord = args.uvBottomRight,
+        .color = args.color
     };
     const UIVertex bottomLeft = {
         .pos = {topLeft.pos.x, bottomRight.pos.y},
-        .texcoord = {topLeft.texcoord.x, bottomRight.texcoord.y}
+        .texcoord = {topLeft.texcoord.x, bottomRight.texcoord.y},
+        .color = args.color
     };
     const UIVertex topRight = {
         .pos = {bottomRight.pos.x, topLeft.pos.y},
-        .texcoord = {bottomRight.texcoord.x, topLeft.texcoord.y}
+        .texcoord = {bottomRight.texcoord.x, topLeft.texcoord.y},
+        .color = args.color
     };
 
     mUIVertices.push_back(topLeft);
diff --git a/private/sdl_gpu_test/6_ui/ui/ui_renderer.hpp b/private/sdl_gpu_test/6_ui/ui/ui_renderer.hpp
index 57a2458..d97aea0 100644
--- a/private/sdl_gpu_test/6_ui/ui/ui_renderer.hpp
+++ b/private/sdl_gpu_test/6_ui/ui/ui_renderer.hpp
@@ -24,6 +24,7 @@ struct DrawTextArgs
     unsigned x = 0;
     unsigned y = 0;
     std::string_view text;
+    glm::vec4 color = glm::vec4(1.f);
 };
 
 struct DrawCharArgs
@@ -31,6 +32,7 @@ struct DrawCharArgs
     unsigned x = 0;
     unsigned y = 0;
     char chr;
+    glm::vec4 color = glm::vec4(1.f);
 };
 
 struct UIRendererRenderArgs
@@ -64,6 +66,7 @@ private:
         glm::vec2 bottomRight;
         glm::vec2 uvTopLeft;
         glm::vec2 uvBottomRight;
+        glm::vec4 color = glm::vec4(1.f);
     };
     void drawQuadInternal(const DrawQuadInternalArgs& args);
 };