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opengl.texture.coordinates: Add 'centroid' as part of the result in simple function to compute texture coordinates from a set of vertices.

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This commit is contained in:
Rod Kay
2023-11-14 22:22:43 +11:00
parent ae8cee1cce
commit fa02760f9c
3 changed files with 38 additions and 32 deletions
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37
3-mid/opengl/source/lean/opengl-texture-coordinates.adb
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@@ -1,14 +1,14 @@
package body openGL.Texture.Coordinates
is
function to_Coordinates (the_Vertices : in Vector_2_array) return Coordinates_2D
function to_Coordinates (the_Vertices : in Vector_2_array) return Coords_2D_and_Centroid
is
Centroid : Vector_2 := (0.0, 0.0);
Min : Vector_2 := (Real'Last, Real'Last);
Max : Vector_2 := (Real'First, Real'First);
Centroid : Vector_2 := [0.0, 0.0];
Min : Vector_2 := [Real'Last, Real'Last];
Max : Vector_2 := [Real'First, Real'First];
Coords : Vector_2;
Result : Coordinates_2D (1 .. the_Vertices'Length);
Result : Coords_2D_and_Centroid (coords_Count => the_Vertices'Length);
begin
--- Calculate the centroid and min/max of x and y.
--
@@ -16,44 +16,43 @@ is
loop
Centroid := Centroid + the_Vertices (i);
Min (1) := Real'Min (Min (1),
the_Vertices (i) (1));
Min (2) := Real'Min (Min (2),
the_Vertices (i) (2));
Min (1) := Real'Min (Min (1), the_Vertices (i) (1));
Min (2) := Real'Min (Min (2), the_Vertices (i) (2));
Max (1) := Real'Max (Max (1),
the_Vertices (i) (1));
Max (2) := Real'Max (Max (2),
the_Vertices (i) (2));
Max (1) := Real'Max (Max (1), the_Vertices (i) (1));
Max (2) := Real'Max (Max (2), the_Vertices (i) (2));
end loop;
Centroid := Centroid / Real (the_Vertices'Length);
declare
half_Width : constant Real := (Max (1) - Min (1)) / 2.0;
half_Height : constant Real := (Max (2) - Min (2)) / 2.0;
begin
for i in the_Vertices'Range
loop
Coords := the_Vertices (i) - Centroid; -- The centroid is now the origin.
Coords := the_Vertices (i) - Centroid; -- The centroid is now the origin.
Coords (1) := Coords (1) / half_Width;
Coords (2) := Coords (2) / half_Height; -- The coords are now in range -1.0 .. 1.0.
Coords (1) := (Coords (1) + 1.0) / 2.0;
Coords (2) := (Coords (2) + 1.0) / 2.0; -- The coords are now in range 0.0 .. 1.0.
Coords (1) := (Coords (1) + 1.0) / 2.0;
Coords (2) := (Coords (2) + 1.0) / 2.0; -- The coords are now in range 0.0 .. 1.0.
Result (Index_t (i)) := (Coords (1), Coords (2));
Result.Coords (Index_t (i)) := (Coords (1),
Coords (2));
end loop;
end;
Result.Centroid := Centroid;
return Result;
end to_Coordinates;
overriding
function to_Coordinates (Self : in xz_Generator; the_Vertices : access Sites) return Coordinates_2D
is