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Viewport.h
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Viewport.h
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#ifndef _ECHOVIEWPORT_H_
#define _ECHOVIEWPORT_H_
#include <echo/Types.h>
#include <echo/Graphics/Colour.h>
namespace Echo
{
/**
* A Viewport represents a rendering area within a RenderTarget.
* Viewports are defined as coordinates from top left (0,0) to bottom right (1,1)
* The viewport class also provides functionality for automatic adjustment for
* a given aspect ratio. This allows you to specify the aspect ratio that you want
* the Viewport to maintain and it will automatically adjust as needed to fit with
* the correct aspect ratio on the render target. There are a number of different
* modes to accomplish this each having a different behaviour.
* @note All coordinates specified here are in viewport coordinates which represent
* percentages of the width and height of the RenderTarget.
*/
class Viewport
{
public:
/**
* Rectangle contains the position of the viewport in percent values of the
* RenderTarget. For example a Rectangle with a left of 0, top of 0, right of 1
* and bottom of 0.5 will take up the top half of the render target.
*/
struct Rectangle
{
Rectangle(f32 l=0.f,f32 t=0.f,f32 r=1.f,f32 b=1.f) : mLeft(l), mTop(t), mRight(r), mBottom(b){}
f32 mLeft;
f32 mTop;
f32 mRight;
f32 mBottom;
inline f32 GetWidth() const {return mRight-mLeft;}
inline f32 GetHeight() const {return mBottom-mTop;}
bool operator==(const Rectangle& rhs)
{
return (mLeft==rhs.mLeft &&
mTop==rhs.mTop &&
mRight==rhs.mRight &&
mBottom==rhs.mBottom);
}
};
Viewport(f32 left=0.0f, f32 top=0.0f, f32 right=1.0f, f32 bottom=1.0f);
~Viewport();
/**
* Set the viewport to best fit the area specified by the coordinates.
* If the RenderTarget changes in size the viewport will always ensure it is entirely visible
* within the provided area. Depending on the aspect ratio of the RenderTarget, this may cause
* bars on the top and bottom or on the left and right of the viewport.
* @param displayAspectRatio The aspect ratio the viewport is to maintain.
* @param left Viewport left coordinate.
* @param top Viewport top coordinate.
* @param right Viewport right coordinate.
* @param bottom Viewport Bottom coordinate.
*/
void SetMaxFit(f32 displayAspectRatio, f32 left=0.0f, f32 top=0.0f, f32 right=1.0f, f32 bottom=1.0f);
/**
*@see SetMaxFit(f32, f32, f32, f32, f32)f
*/
void SetMaxFit(f32 displayAspectRatio, Rectangle rectangle);
/**
* Set the viewport with a fixed aspect ratio and always maintain the horizontal size.
* @note This method may cause the viewport to extend beyond the top and bottom of the render target.
* This can cause part of your scene to be cut off from view. RenderTarget implementations must also
* ensure to clamp if necessary.
* @param displayAspectRatio The aspect ratio the viewport is to maintain.
* @param left The left coordinate of the viewport.
* @param right The right coordinate of the viewport.
* @param verticalCentre The vertical centre of the viewport. The top and bottom values will be
* calculated with this as a centre.
*/
void SetAsHorizontal(f32 displayAspectRatio, f32 left=0.0f, f32 right=1.0f, f32 verticalCentre=0.5f);
/**
* Set the viewport with a fixed aspect ratio and always maintain the vertical size.
* @note This method may cause the viewport to extend beyond the left and right of the render target.
* This can cause part of your scene to be cut off from view. RenderTarget implementations must also
* ensure to clamp if necessary.
* @param displayAspectRatio The aspect ratio the viewport is to maintain.
* @param top The top coordinate of the viewport.
* @param bottom The bottom coordinate of the viewport.
* @param horizontalCentre The horizontal centre of the viewport. The left and right values will be
* calculated with this as a centre.
*/
void SetAsVertical(f32 displayAspectRatio, f32 top=0.0f, f32 bottom=1.0f, f32 horizontalCentre=0.5f);
/**
* Set the viewport coordinates as fixed values.
* The viewport will always use the provided values as the values for the RenderTarget. This can
* cause stretching/squashing of your view if the camera isn't automatically adjusting for the aspect
* ratio change.
* @param left Viewport left coordinate.
* @param top Viewport top coordinate.
* @param right Viewport right coordinate.
* @param bottom Viewport Bottom coordinate.
*/
void SetFixed(f32 left=0.0f, f32 top=0.0f, f32 right=1.0f, f32 bottom=1.0f);
/**
* Get the aspect ratio.
* The aspect ratio will either be the one provided in one of the set methods above, except in the
* case of SetFixed() where the aspect ratio will be the aspect ratio of the percentage values (it
* is known that this value isn't necessarily very useful).
* @return The aspect ratio.
*/
f32 GetAspectRatio() const
{
return mAspectRatio;
}
/**
* Get whether the viewport has a fixed aspect ratio.
* If the viewport has been set with one of the Set methods other than SetFixed() then the aspect
* ratio will be fixed.
* @return true if the aspect ratio is fixed, otherwise false.
*/
bool GetHasFixedAspectRatio() const {return mHasFixedAspectRatio;}
/**
* Get the rectangle of the viewport.
* @param targetsAspectRatio The aspect ratio of the target you are going to use the viewport for.
* @return A Rectangle object that contains the coordinates as adjusted for the viewport settings.
*/
Rectangle GetRectangle(f32 targetsAspectRatio) const;
private:
struct SizeOptions
{
enum _
{
STRETCH,
WIDTH_FIRST_PRESERVE_ASPECT_RATIO, ///As per SetAsHorizontal().
HEIGHT_FIRST_PRESERVE_ASPECT_RATIO, ///As per SetAsVertical().
MAX_FIT_PRESERVE_ASPECT_RATIO ///As per SetMaxFit().
};
};
typedef SizeOptions::_ SizeOption;
Rectangle mRectangle;
f32 mAspectRatio;
SizeOption mSizeOption;
bool mHasFixedAspectRatio;
};
}
#endif

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