FrameBuffer Class Reference

Image framebuffer object which can be rendered on. More...

#include <jngl/FrameBuffer.hpp>

Classes
struct	Context
	Lifetime object when the FrameBuffer is in use. More...

Public Member Functions
	FrameBuffer (Pixels width, Pixels height, bool hdr=false, bool antiAliased=false)
	Creates a framebuffer object with width times height actual pixels.
	FrameBuffer (ScaleablePixels width, ScaleablePixels height, bool hdr=false, bool antiAliased=false)
	Creates a framebuffer object with width times height scalable pixels.
	FrameBuffer (std::array< Pixels, 2 > size, bool hdr=false, bool antiAliased=false)
	Creates a framebuffer object with size[0] times size[1] pixels.
	FrameBuffer (const FrameBuffer &)=delete
FrameBuffer &	operator= (const FrameBuffer &)=delete
	FrameBuffer (FrameBuffer &&) noexcept
FrameBuffer &	operator= (FrameBuffer &&) noexcept
Context	use () const
	Starts drawing on the FrameBuffer as long as Context is alive.
void	draw (Vec2 position, const ShaderProgram *=nullptr) const
	Draws the framebuffer image to the screen.
void	draw (double x, double y) const
void	draw (Mat3 modelview, const ShaderProgram *=nullptr) const
	Draws the framebuffer image to the screen.
void	draw (Mat3 modelview, TextureFilter textureFilter, const ShaderProgram *=nullptr) const
	Draws the framebuffer image to the screen with a specific texture filter.
void	drawMesh (const std::vector< Vertex > &vertexes, const ShaderProgram *=nullptr) const
	Draws a list of triangles with the framebuffer's texture on it.
void	drawMesh (const Mat3 &modelview, const std::vector< Vertex > &vertexes, const ShaderProgram *shaderProgram=nullptr) const
	Draws a list of triangles with the framebuffer's texture on it, with modelview instead of the global one, and tinted by color, e.g.
void	drawMesh (const Mat3 &modelview, const std::vector< Vertex > &vertexes, Rgba color, const ShaderProgram *=nullptr) const
Vec2	getSize () const
	Returns the size in screen pixels.
Pixels	getPixelWidth () const
Pixels	getPixelHeight () const
uint32_t	getTextureID () const
	Returns the OpenGL texture ID of the associated image buffer.

Static Public Member Functions
static void	clear ()
	Clear the framebuffer with the color set by jngl::setBackgroundColor.

Detailed Description

Image framebuffer object which can be rendered on.

Example:

FrameBuffer foo(300_px, 200_px);
// ...
{
    auto context = foo.use();
    context.clear(0xff0000_rgb);
    jngl::print("Hello World!", jngl::Vec2(-100, -20));
} // jngl::FrameBuffer::Context is destroyed, now drawing on the main buffer again
// ...
foo.draw(jngl::modelview()); // draws a red rectangle with Hello World! on it

Definition at line 38 of file FrameBuffer.hpp.

Constructor & Destructor Documentation

FrameBuffer()

FrameBuffer	(	Pixels	width,
		Pixels	height,
		bool	hdr = false,
		bool	antiAliased = false )

Creates a framebuffer object with width times height actual pixels.

Parameters

hdr

If true, the framebuffer stores floating point channels (GL_RGBA16F) instead of 8-bit ones. This avoids banding in smooth gradients and lets channel values exceed 1.0, which is useful for HDR lighting.

antiAliased

If true, what's drawn into it is anti-aliased like what's drawn onto the window: multisampled as long as jngl::getAntiAliasing() is true and the window supports it. Each time it's done being used (see use()), the samples are resolved into the image that's drawn, which costs a little, so it's only worth it for shapes, e.g. jngl::drawCircle(), not for e.g. sprites, which are smooth anyway. While jngl::setAntiAliasing(false), it still has its samples and resolves them, only without smoothing anything (except on OpenGL ES, which can't turn it off, like on the window): to save that too, make it again with antiAliased false.

Member Function Documentation

use()

Context use

(

)

const

Starts drawing on the FrameBuffer as long as Context is alive.

The projection matrix gets adjusted so that (0, 0) is in the center of the FrameBuffer. The modelview matrix is saved (i.e. pushMatrix() is called) and restored by ~Context (i.e. popMatrix() is called).

draw() [1/2]

void draw	(	Mat3	modelview,
		const ShaderProgram *	= nullptr ) const

Draws the framebuffer image to the screen.

Parameters

shaderProgram

If not nullptr, this shader program is used instead of the default.

draw() [2/2]

void draw	(	Mat3	modelview,
		TextureFilter	textureFilter,
		const ShaderProgram *	= nullptr ) const

Draws the framebuffer image to the screen with a specific texture filter.

Parameters

textureFilter	Use this filtering for this one draw call, ignoring jngl::AppParameters::pixelArt. You'd probably want to use TextureFilter::NearestNeighbor for cases where you have a framebuffer the same size as the screen.
shaderProgram	If not nullptr, this shader program is used instead of the default.

drawMesh() [1/2]

void drawMesh	(	const std::vector< Vertex > &	vertexes,
		const ShaderProgram *	= nullptr ) const

Draws a list of triangles with the framebuffer's texture on it.

The texture's v coordinate runs from 1 at the framebuffer's top to 0 at its bottom.

drawMesh() [2/2]

void drawMesh	(	const Mat3 &	modelview,
		const std::vector< Vertex > &	vertexes,
		const ShaderProgram *	shaderProgram = nullptr ) const

Draws a list of triangles with the framebuffer's texture on it, with modelview instead of the global one, and tinted by color, e.g.

its alpha for a see-through framebuffer

Parameters

shaderProgram

Passing nullptr uses the default.

clear()

static void clear ( )

static

Clear the framebuffer with the color set by jngl::setBackgroundColor.

Deprecated

use jngl::FrameBuffer::Context::clear(Color) instead

getTextureID()

uint32_t getTextureID

(

)

const

Returns the OpenGL texture ID of the associated image buffer.

While this is an implementation detail, it can be useful if you want to draw the GL_TEXTURE_2D object yourself or need to pass it to another library. The return type is equivalent to GLuint.

Deprecated

There's no OpenGL texture with other rendering backends (e.g. Vulkan). Draw the FrameBuffer with draw() instead, also with your own ShaderProgram.

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The documentation for this class was generated from the following file:

• jngl/FrameBuffer.hpp