libgui|GLBuffer: Added "TexBounds0" vertex attribute

The texture bounds attribute is useful for example when rendering geometry that uses a shared texture atlas; one can store the individual texture bounds in the vertex data and use normalized (0,1) UV coordinates, which a shader will then convert to coordinates on the atlas. This also allows repeating UV patterns by applying wrapping in the shader.
skyjake · Mar 5, 2014 · 7084b82 · 7084b82
1 parent 0cbf724
commit 7084b82
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Showing 3 changed files with 33 additions and 9 deletions.
diff --git a/doomsday/libgui/include/de/gui/glbuffer.h b/doomsday/libgui/include/de/gui/glbuffer.h
@@ -43,6 +43,7 @@ namespace internal
             TexCoord1,
             TexCoord2,
             TexCoord3,
+            TexBounds0,
             Color,
             Normal,
             Tangent,
@@ -130,6 +131,20 @@ struct LIBGUI_PUBLIC Vertex3TexRgba
     LIBGUI_DECLARE_VERTEX_FORMAT(3)
 };
 
+/**
+ * Vertex format with 3D coordinates, one set of texture coordinates with indirect
+ * bounds, and an RGBA color.
+ */
+struct LIBGUI_PUBLIC Vertex3TexBoundsRgba
+{
+    Vector3f pos;
+    Vector2f texCoord;  ///< mapped using texBounds
+    Vector4f texBounds; ///< UV space: x, y, width, height
+    Vector4f rgba;
+
+    LIBGUI_DECLARE_VERTEX_FORMAT(4)
+};
+
 /**
  * Vertex format with 3D coordinates, two sets of texture coordinates, and an
  * RGBA color.

diff --git a/doomsday/libgui/src/glbuffer.cpp b/doomsday/libgui/src/glbuffer.cpp
@@ -59,6 +59,14 @@ AttribSpec const Vertex3TexRgba::_spec[3] = {
 };
 LIBGUI_VERTEX_FORMAT_SPEC(Vertex3TexRgba, 9 * sizeof(float))
 
+AttribSpec const Vertex3TexBoundsRgba::_spec[4] = {
+    { AttribSpec::Position,   3, GL_FLOAT, false, sizeof(Vertex3TexBoundsRgba), 0 },
+    { AttribSpec::TexCoord0,  2, GL_FLOAT, false, sizeof(Vertex3TexBoundsRgba), 3 * sizeof(float) },
+    { AttribSpec::TexBounds0, 4, GL_FLOAT, false, sizeof(Vertex3TexBoundsRgba), 5 * sizeof(float) },
+    { AttribSpec::Color,      4, GL_FLOAT, false, sizeof(Vertex3TexBoundsRgba), 9 * sizeof(float) }
+};
+LIBGUI_VERTEX_FORMAT_SPEC(Vertex3TexBoundsRgba, 13 * sizeof(float))
+
 AttribSpec const Vertex3Tex2Rgba::_spec[4] = {
     { AttribSpec::Position,  3, GL_FLOAT, false, sizeof(Vertex3Tex2Rgba), 0 },
     { AttribSpec::TexCoord0, 2, GL_FLOAT, false, sizeof(Vertex3Tex2Rgba), 3 * sizeof(float) },

diff --git a/doomsday/libgui/src/glprogram.cpp b/doomsday/libgui/src/glprogram.cpp
@@ -164,15 +164,16 @@ DENG2_PIMPL(GLProgram)
             char const *varName;
         }
         const names[] = {
-            { AttribSpec::Position,  "aVertex"    },
-            { AttribSpec::TexCoord0, "aUV"        },
-            { AttribSpec::TexCoord1, "aUV2"       },
-            { AttribSpec::TexCoord2, "aUV3"       },
-            { AttribSpec::TexCoord3, "aUV4"       },
-            { AttribSpec::Color,     "aColor"     },
-            { AttribSpec::Normal,    "aNormal"    },
-            { AttribSpec::Tangent,   "aTangent"   },
-            { AttribSpec::Bitangent, "aBitangent" }
+            { AttribSpec::Position,   "aVertex"    },
+            { AttribSpec::TexCoord0,  "aUV"        },
+            { AttribSpec::TexCoord1,  "aUV2"       },
+            { AttribSpec::TexCoord2,  "aUV3"       },
+            { AttribSpec::TexCoord3,  "aUV4"       },
+            { AttribSpec::TexBounds0, "aBounds"    },
+            { AttribSpec::Color,      "aColor"     },
+            { AttribSpec::Normal,     "aNormal"    },
+            { AttribSpec::Tangent,    "aTangent"   },
+            { AttribSpec::Bitangent,  "aBitangent" }
         };
 
         for(uint i = 0; i < sizeof(names)/sizeof(names[0]); ++i)