143 lines
5.3 KiB
Go
143 lines
5.3 KiB
Go
package pixel
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import "image/color"
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// Target is something that can be drawn onto, such as a window, a canvas, and so on.
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//
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// You can notice, that there are no "drawing" methods in a Target. That's because all drawing
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// happens indirectly through Triangles and Picture instances generated via MakeTriangles and
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// MakePicture method.
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type Target interface {
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// MakeTriangles generates a specialized copy of the provided Triangles.
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//
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// When calling Draw method on the returned TargetTriangles, the TargetTriangles will be
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// drawn onto the Target that generated them.
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//
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// Note, that not every Target has to recognize all possible types of Triangles. Some may
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// only recognize TrianglesPosition and TrianglesColor and ignore all other properties (if
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// present) when making new TargetTriangles. This varies from Target to Target.
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MakeTriangles(Triangles) TargetTriangles
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// MakePicture generates a specialized copy of the provided Picture.
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//
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// When calling Draw method on the returned TargetPicture, the TargetPicture will be drawn
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// onto the Target that generated it together with the TargetTriangles supplied to the Draw
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// method.
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MakePicture(Picture) TargetPicture
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}
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// BasicTarget is a Target with additional basic adjustment methods.
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type BasicTarget interface {
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Target
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// SetMatrix sets a Matrix that every point will be projected by.
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SetMatrix(Matrix)
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// SetColorMask sets a color that will be multiplied with the TrianglesColor property of all
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// Triangles.
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SetColorMask(color.Color)
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}
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// Triangles represents a list of vertices, where each three vertices form a triangle. (First,
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// second and third is the first triangle, fourth, fifth and sixth is the second triangle, etc.)
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type Triangles interface {
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// Len returns the number of vertices. The number of triangles is the number of vertices
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// divided by 3.
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Len() int
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// SetLen resizes Triangles to len vertices. If Triangles B were obtained by calling Slice
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// method on Triangles A, the relationship between A and B is undefined after calling SetLen
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// on either one of them.
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SetLen(len int)
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// Slice returns a sub-Triangles of this Triangles, covering vertices in range [i, j).
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//
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// If Triangles B were obtained by calling Slice(4, 9) on Triangles A, then A and B must
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// share the same underlying data. Modifying B must change the contents of A in range
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// [4, 9). The vertex with index 0 at B is the vertex with index 4 in A, and so on.
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//
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// Returned Triangles must have the same underlying type.
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Slice(i, j int) Triangles
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// Update copies vertex properties from the supplied Triangles into this Triangles.
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//
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// Properies not supported by these Triangles should be ignored. Properties not supported by
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// the supplied Triangles should be left untouched.
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//
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// The two Triangles must have the same Len.
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Update(Triangles)
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// Copy creates an exact independent copy of this Triangles (with the same underlying type).
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Copy() Triangles
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}
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// TargetTriangles are Triangles generated by a Target with MakeTriangles method. They can be drawn
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// onto that (no other) Target.
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type TargetTriangles interface {
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Triangles
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// Draw draws Triangles onto an associated Target.
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Draw()
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}
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// TrianglesPosition specifies Triangles with Position property.
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type TrianglesPosition interface {
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Triangles
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Position(i int) Vec
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}
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// TrianglesColor specifies Triangles with Color property.
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type TrianglesColor interface {
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Triangles
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Color(i int) RGBA
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}
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// TrianglesPicture specifies Triangles with Picture property.
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//
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// The first value returned from Picture method is Picture coordinates. The second one specifies the
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// weight of the Picture. Value of 0 means, that Picture should be completely ignored, 1 means that
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// is should be fully included and anything in between means anything in between.
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type TrianglesPicture interface {
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Triangles
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Picture(i int) (pic Vec, intensity float64)
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}
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// TrianglesClipped specifies Triangles with Clipping Rectangle property.
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//
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// The first value returned from ClipRect method is the clipping rectangle. The second one specifies
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// if the triangle is clipped.
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type TrianglesClipped interface {
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Triangles
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ClipRect(i int) (rect Rect, is bool)
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}
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// Picture represents a rectangular area of raster data, such as a color. It has Bounds which
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// specify the rectangle where data is located.
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type Picture interface {
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// Bounds returns the rectangle of the Picture. All data is located within this rectangle.
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// Querying properties outside the rectangle should return default value of that property.
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Bounds() Rect
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}
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// TargetPicture is a Picture generated by a Target using MakePicture method. This Picture can be drawn onto
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// that (no other) Target together with a TargetTriangles generated by the same Target.
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//
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// The TargetTriangles specify where, shape and how the Picture should be drawn.
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type TargetPicture interface {
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Picture
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// Draw draws the supplied TargetTriangles (which must be generated by the same Target as
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// this TargetPicture) with this TargetPicture. The TargetTriangles should utilize the data
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// from this TargetPicture in some way.
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Draw(TargetTriangles)
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}
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// PictureColor specifies Picture with Color property, so that every position inside the Picture's
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// Bounds has a color.
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//
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// Positions outside the Picture's Bounds must return full transparent (Alpha(0)).
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type PictureColor interface {
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Picture
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Color(at Vec) RGBA
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}
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