SLBackground Class Reference

Defines a 2D-Background for the OpenGL framebuffer background. More...

#include <SLBackground.h>

Inheritance diagram for SLBackground:

Public Member Functions
	SLBackground (SLstring shaderDir)
	The constructor initializes to a uniform BLACK background color. More...
	SLBackground (SLGLProgram *textureOnlyProgram, SLGLProgram *colorAttributeProgram)
	The constructor initializes to a uniform gray background color. More...
	~SLBackground ()
void	render (SLint widthPX, SLint heightPX)
	Draws the background as 2D rectangle with OpenGL buffers. More...
void	renderInScene (const SLMat4f &wm, const SLVec3f &LT, const SLVec3f &LB, const SLVec3f &RT, const SLVec3f &RB)
	Draws the background as a quad on the far clipping plane. More...
SLCol4f	colorAtPos (SLfloat x, SLfloat y, SLfloat width, SLfloat height)
	Returns the interpolated color at the pixel position p[x,y] used in raytracing. More...
void	rebuild ()
void	colors (const SLCol4f &uniformColor)
	Sets a uniform background color. More...
void	colors (const SLCol4f &topColor, const SLCol4f &bottomColor)
	Sets a gradient top-down background color. More...
void	colors (const SLCol4f &topLeftColor, const SLCol4f &bottomLeftColor, const SLCol4f &topRightColor, const SLCol4f &bottomRightColor)
	Sets a gradient background color with a color per corner. More...
void	texture (SLGLTexture *backgroundTexture, bool fixAspectRatio=false)
	If flag _repeatBlurred is true the texture is not distorted if its size does not fit to screen aspect ratio. Instead it is repeated. More...
SLVCol4f	colors ()
SLCol4f	avgColor ()
SLbool	isUniform () const
SLGLTexture *	texture ()
const SLRectf &	rect () const
Public Member Functions inherited from SLObject
	SLObject (const SLstring &Name="", const SLstring &url="")
virtual	~SLObject ()
void	name (const SLstring &Name)
void	url (const SLstring &url)
const SLstring &	name () const
const SLstring &	url () const

Private Attributes
SLbool	_isUniform
	Flag if background has uniform color. More...
SLVCol4f	_colors
	Vector of 4 corner colors {TL,BL,TR,BR}. More...
SLCol4f	_avgColor
	Average color of all 4 corner colors. More...
SLGLTexture *	_texture
	Pointer to a background texture. More...
SLGLTexture *	_textureError
	Pointer to a error texture if background texture is not available. More...
SLint	_resX
	Background resolution in x-dir. More...
SLint	_resY
	Background resolution in y-dir. More...
SLRectf	_rect
	Background rect (it may be different to viewport size) More...
SLGLVertexArray	_vao
	OpenGL Vertex Array Object for drawing. More...
SLGLProgram *	_textureOnlyProgram = nullptr
SLGLProgram *	_colorAttributeProgram = nullptr
bool	_deletePrograms = false
bool	_fixAspectRatio = false
	if true, the background is centered and stretched to the screen boarders while keeping the textures aspect ratio More...

Additional Inherited Members
Protected Attributes inherited from SLObject
SLstring	_name
	name of an object More...
SLstring	_url
	uniform resource locator More...

Detailed Description

Defines a 2D-Background for the OpenGL framebuffer background.

The background can either be defined with a texture or with 4 colors for the corners of the frame buffer. For a uniform background color the color at index 0 of the _colors vector is taken. Every instance of SLCamera has a background that is displayed on the far clipping plane if the camera is not the active one. The OpenGL rendering is done in SLSceneView::draw3DGL for the active camera or in SLCamera::drawMeshes for inactive ones.

Definition at line 28 of file SLBackground.h.

Constructor & Destructor Documentation

SLBackground() [1/2]

SLBackground::SLBackground

(

SLstring

shaderDir

)

The constructor initializes to a uniform BLACK background color.

Definition at line 17 of file SLBackground.cpp.

  : SLObject("Background")
{
    _colors.push_back(SLCol4f::BLACK); // bottom left
    _colors.push_back(SLCol4f::BLACK); // bottom right
    _colors.push_back(SLCol4f::BLACK); // top right
    _colors.push_back(SLCol4f::BLACK); // top left
    _avgColor     = SLCol4f::BLACK;
    _isUniform    = true;
    _texture      = nullptr;
    _textureError = nullptr;
    _resX         = -1;
    _resY         = -1;
 
    _textureOnlyProgram = new SLGLProgramGeneric(nullptr,
                                                 shaderDir + "TextureOnly.vert",
                                                 shaderDir + "TextureOnly.frag");
 
    _colorAttributeProgram = new SLGLProgramGeneric(nullptr,
                                                    shaderDir + "ColorAttribute.vert",
                                                    shaderDir + "Color.frag");
    _deletePrograms        = true;
}

SLBackground() [2/2]

SLBackground::SLBackground	(	SLGLProgram *	textureOnlyProgram,
		SLGLProgram *	colorAttributeProgram
	)

The constructor initializes to a uniform gray background color.

Definition at line 42 of file SLBackground.cpp.

  : SLObject("Background"),
    _textureOnlyProgram(textureOnlyProgram),
    _colorAttributeProgram(colorAttributeProgram),
    _deletePrograms(false)
{
    _colors.push_back(SLCol4f::BLACK); // bottom left
    _colors.push_back(SLCol4f::BLACK); // bottom right
    _colors.push_back(SLCol4f::BLACK); // top right
    _colors.push_back(SLCol4f::BLACK); // top left
    _avgColor     = SLCol4f::BLACK;
    _isUniform    = true;
    _texture      = nullptr;
    _textureError = nullptr;
    _resX         = -1;
    _resY         = -1;
}

~SLBackground()

SLBackground::~SLBackground

(

)

Definition at line 61 of file SLBackground.cpp.

{
    if (_deletePrograms)
    {
        delete _textureOnlyProgram;
        delete _colorAttributeProgram;
    }
}

Member Function Documentation

avgColor()

SLCol4f SLBackground::avgColor ( )

inline

Definition at line 56 of file SLBackground.h.

{ return _avgColor; }

colorAtPos()

SLCol4f SLBackground::colorAtPos	(	SLfloat	x,
		SLfloat	y,
		SLfloat	width,
		SLfloat	height
	)

Returns the interpolated color at the pixel position p[x,y] used in raytracing.

Returns the interpolated color at the pixel position p[x,y] for ray tracing. x is expected to be between 0 and width of the RT-frame. y is expected to be between 0 and height of the RT-frame. width is the width of the RT-frame height is the height of the RT-frame

C w B +--—+ | p /| | * / | h | / | | / | |/ | 0 +--—+ A 0

Definition at line 331 of file SLBackground.cpp.

{
    if (_isUniform)
        return _colors[0];
 
    if (_texture)
        return _texture->getTexelf(x / width, y / height);
 
    // top-down gradient
    if (_colors[0] == _colors[2] && _colors[1] == _colors[3])
    {
        SLfloat f = y / height;
        return f * _colors[0] + (1 - f) * _colors[1];
    }
    // left-right gradient
    if (_colors[0] == _colors[1] && _colors[2] == _colors[3])
    {
        SLfloat f = x / width;
        return f * _colors[0] + (1 - f) * _colors[2];
    }
 
    // Quadrilateral interpolation
    // First check with barycentric coords if p is in the upper left triangle
    SLVec2f p(x, y);
    SLVec3f bc(p.barycentricCoords(SLVec2f(0, 0),
                                   SLVec2f(width, height),
                                   SLVec2f(0, height)));
    SLfloat u = bc.x;
    SLfloat v = bc.y;
    SLfloat w = 1 - bc.x - bc.y;
 
    SLCol4f color;
 
    if (u > 0 && v > 0 && u + v <= 1)
        color = w * _colors[0] + u * _colors[1] + v * _colors[2]; // upper left triangle
    else
    {
        u     = 1 - u;
        v     = 1 - v;
        w     = 1 - u - v;
        color = w * _colors[3] + v * _colors[1] + u * _colors[2]; // lower right triangle
    }
 
    return color;
}

colors() [1/4]

SLVCol4f SLBackground::colors ( )

inline

Definition at line 55 of file SLBackground.h.

{ return _colors; }

colors() [2/4]

void SLBackground::colors	(	const SLCol4f &	topColor,
		const SLCol4f &	bottomColor
	)

Sets a gradient top-down background color.

Definition at line 84 of file SLBackground.cpp.

{
    _colors[0].set(topColor);
    _colors[1].set(bottomColor);
    _colors[2].set(topColor);
    _colors[3].set(bottomColor);
    _avgColor  = (topColor + bottomColor) / 2.0f;
    _isUniform = false;
    _texture   = nullptr;
    //_vao.clearAttribs(); Not allowed here during assembly
}

colors() [3/4]

void SLBackground::colors	(	const SLCol4f &	topLeftColor,
		const SLCol4f &	bottomLeftColor,
		const SLCol4f &	topRightColor,
		const SLCol4f &	bottomRightColor
	)

Sets a gradient background color with a color per corner.

Definition at line 98 of file SLBackground.cpp.

{
    _colors[0].set(topLeftColor);
    _colors[1].set(bottomLeftColor);
    _colors[2].set(topRightColor);
    _colors[3].set(bottomRightColor);
    _avgColor  = (_colors[0] + _colors[1] + _colors[2] + _colors[3]) / 4.0f;
    _isUniform = false;
    _texture   = nullptr;
    _vao.clearAttribs();
}

colors() [4/4]

void SLBackground::colors

(

const SLCol4f &

uniformColor

)

Sets a uniform background color.

Definition at line 71 of file SLBackground.cpp.

{
    _colors[0].set(uniformColor);
    _colors[1].set(uniformColor);
    _colors[2].set(uniformColor);
    _colors[3].set(uniformColor);
    _avgColor  = uniformColor;
    _isUniform = true;
    _texture   = nullptr;
    _vao.clearAttribs();
}

isUniform()

SLbool SLBackground::isUniform ( ) const

inline

Definition at line 57 of file SLBackground.h.

{ return _isUniform; }

rebuild()

void SLBackground::rebuild ( )

inline

Definition at line 42 of file SLBackground.h.

{ _vao.clearAttribs(); }

rect()

const SLRectf& SLBackground::rect ( ) const

inline

Definition at line 59 of file SLBackground.h.

{ return _rect; }

render()

void SLBackground::render	(	SLint	widthPX,
		SLint	heightPX
	)

Draws the background as 2D rectangle with OpenGL buffers.

Draws the background as a flat 2D rectangle with a height and a width on two triangles with zero in the bottom left corner:
w +--—+ | /| | / | h | / | | / | |/ | 0 +--—+ 0

We render the quad as a triangle strip:
0 2 +--—+ | /| | / | | / | | / | |/ | +--—+ 1 3

Definition at line 148 of file SLBackground.cpp.

{
    SLGLState* stateGL = SLGLState::instance();
 
    // Set orthographic projection
    stateGL->projectionMatrix.ortho(0.0f, (SLfloat)widthPX, 0.0f, (SLfloat)heightPX, 0.0f, 1.0f);
    stateGL->modelMatrix.identity();
    stateGL->viewMatrix.identity();
    stateGL->depthTest(false);
    stateGL->multiSample(false);
 
    // Get shader program
    SLGLProgram* sp = _texture ? _textureOnlyProgram : _colorAttributeProgram;
    sp->useProgram();
    sp->uniformMatrix4fv("u_mMatrix", 1, (SLfloat*)&stateGL->modelMatrix);
    sp->uniformMatrix4fv("u_vMatrix", 1, (SLfloat*)&stateGL->viewMatrix);
    sp->uniformMatrix4fv("u_pMatrix", 1, (SLfloat*)&stateGL->projectionMatrix);
    sp->uniform1f("u_oneOverGamma", SLLight::oneOverGamma());
 
    // Create or update buffer for vertex position and indices
    if (!_vao.vaoID() || _resX != widthPX || _resY != heightPX)
    {
        // texture width and height not yet valid on first call
        _resX = widthPX;
        _resY = heightPX;
        _vao.clearAttribs();
 
        SLfloat left = 0, right = (float)_resX, bottom = 0, top = (float)_resY;
 
        // the background is centered and stretched to the screen boarders while keeping the textures aspect ratio
        if (_texture && _fixAspectRatio)
        {
            SLfloat backgroundW, backgroundH;
            if ((SLfloat)_resX / (SLfloat)_resY > (SLfloat)_texture->width() / (SLfloat)_texture->height())
            {
                // screen is wider than texture -> adjust background width
                backgroundH = (float)_resY;
                backgroundW = (float)_resY / (SLfloat)_texture->height() * (SLfloat)_texture->width();
            }
            else
            {
                // screen is more narrow than texture -> adjust background height
                backgroundW = (float)_resX;
                backgroundH = (float)_resX / (SLfloat)_texture->width() * (SLfloat)_texture->height();
            }
 
            left   = (_resX - backgroundW) * 0.5f;
            right  = backgroundW + left;
            bottom = (_resY - backgroundH) * 0.5f;
            top    = backgroundH + bottom;
 
            _rect.set(left, bottom, backgroundW, backgroundH);
            SL_LOG("SLBackground: width:%f height:%f left:%f bottom:%f", rect().width, rect().height, rect().x, rect().x);
        }
        else
            _rect.set(0, 0, (float)widthPX, (float)heightPX);
 
        // Float array with vertex X & Y of corners
        SLVVec2f P = {{left, top},
                      {left, bottom},
                      {right, top},
                      {right, bottom}};
 
        _vao.setAttrib(AT_position, AT_position, &P);
 
        // Indexes for a triangle strip
        SLVushort I = {0, 1, 2, 3};
        _vao.setIndices(&I, nullptr);
 
        if (_texture)
        { // Float array of texture coordinates
            SLVVec2f T = {{0.0f, 1.0f}, {0.0f, 0.0f}, {1.0f, 1.0f}, {1.0f, 0.0f}};
            _vao.setAttrib(AT_uv1, AT_uv1, &T);
            _vao.generate(4);
        }
        else
        { // Float array of colors of corners
            SLVVec3f C = {{_colors[0].r, _colors[0].g, _colors[0].b},
                          {_colors[1].r, _colors[1].g, _colors[1].b},
                          {_colors[2].r, _colors[2].g, _colors[2].b},
                          {_colors[3].r, _colors[3].g, _colors[3].b}};
            _vao.setAttrib(AT_color, AT_color, &C);
            _vao.generate(4);
        }
    }
 
    // draw a textured or colored quad
    if (_texture)
    {
        _texture->bindActive(0);
        sp->uniform1i("u_matTexture0", 0);
    }
 
    //////////////////////////////////////
    _vao.drawElementsAs(PT_triangleStrip);
    //////////////////////////////////////
}

renderInScene()

void SLBackground::renderInScene	(	const SLMat4f &	wm,
		const SLVec3f &	LT,
		const SLVec3f &	LB,
		const SLVec3f &	RT,
		const SLVec3f &	RB
	)

Draws the background as a quad on the far clipping plane.

We render the quad as a triangle strip:
LT RT +--—+ | /| | / | | / | | / | |/ | +--—+ LB RB

Definition at line 258 of file SLBackground.cpp.

{
    SLGLState* stateGL = SLGLState::instance();
 
    // Get shader program
    SLGLProgram* sp = _texture
                        ? _textureOnlyProgram
                        : _colorAttributeProgram;
    sp->useProgram();
    sp->uniformMatrix4fv("u_mMatrix", 1, (const SLfloat*)&wm);
    sp->uniformMatrix4fv("u_vMatrix", 1, (const SLfloat*)&stateGL->viewMatrix);
    sp->uniformMatrix4fv("u_pMatrix", 1, (const SLfloat*)&stateGL->projectionMatrix);
 
    // Create or update buffer for vertex position and indices
    _vao.clearAttribs();
 
    // Float array with vertices
    SLVVec3f P = {LT, LB, RT, RB};
    _vao.setAttrib(AT_position, AT_position, &P);
 
    // Indexes for a triangle strip
    SLVushort I = {0, 1, 2, 3};
    _vao.setIndices(&I);
 
    if (_texture)
    { // Float array of texture coordinates
        SLVVec2f T = {{0.0f, 1.0f}, {0.0f, 0.0f}, {1.0f, 1.0f}, {1.0f, 0.0f}};
        _vao.setAttrib(AT_uv1, AT_uv1, &T);
        _vao.generate(4);
    }
    else
    { // Float array of colors of corners
        SLVVec3f C = {{_colors[0].r, _colors[0].g, _colors[0].b},
                      {_colors[1].r, _colors[1].g, _colors[1].b},
                      {_colors[2].r, _colors[2].g, _colors[2].b},
                      {_colors[3].r, _colors[3].g, _colors[3].b}};
        _vao.setAttrib(AT_color, AT_color, &C);
        _vao.generate(4);
    }
 
    // draw a textured or colored quad
    if (_texture)
    {
        _texture->bindActive(0);
        sp->uniform1i("u_matTexture0", 0);
    }
 
    ///////////////////////////////////////
    _vao.drawElementsAs(PT_triangleStrip);
    ///////////////////////////////////////
}

texture() [1/2]

SLGLTexture* SLBackground::texture ( )

inline

Definition at line 58 of file SLBackground.h.

{ return _texture; }

texture() [2/2]

void SLBackground::texture	(	SLGLTexture *	backgroundTexture,
		bool	fixAspectRatio = false
	)

If flag _repeatBlurred is true the texture is not distorted if its size does not fit to screen aspect ratio. Instead it is repeated.

Sets the background texture.

Definition at line 114 of file SLBackground.cpp.

{
    _texture        = backgroundTexture;
    _fixAspectRatio = fixAspectRatio;
    _isUniform      = false;
    _avgColor       = SLCol4f::BLACK;
 
    _vao.clearAttribs();
}

Member Data Documentation

_avgColor

SLCol4f SLBackground::_avgColor

private

Average color of all 4 corner colors.

Definition at line 64 of file SLBackground.h.

_colorAttributeProgram

SLGLProgram* SLBackground::_colorAttributeProgram = nullptr

private

Definition at line 73 of file SLBackground.h.

_colors

SLVCol4f SLBackground::_colors

private

Vector of 4 corner colors {TL,BL,TR,BR}.

Definition at line 63 of file SLBackground.h.

_deletePrograms

bool SLBackground::_deletePrograms = false

private

Definition at line 74 of file SLBackground.h.

_fixAspectRatio

bool SLBackground::_fixAspectRatio = false

private

if true, the background is centered and stretched to the screen boarders while keeping the textures aspect ratio

Definition at line 76 of file SLBackground.h.

_isUniform

SLbool SLBackground::_isUniform

private

Flag if background has uniform color.

Definition at line 62 of file SLBackground.h.

_rect

SLRectf SLBackground::_rect

private

Background rect (it may be different to viewport size)

Definition at line 69 of file SLBackground.h.

_resX

SLint SLBackground::_resX

private

Background resolution in x-dir.

Definition at line 67 of file SLBackground.h.

_resY

SLint SLBackground::_resY

private

Background resolution in y-dir.

Definition at line 68 of file SLBackground.h.

_texture

SLGLTexture* SLBackground::_texture

private

Pointer to a background texture.

Definition at line 65 of file SLBackground.h.

_textureError

SLGLTexture* SLBackground::_textureError

private

Pointer to a error texture if background texture is not available.

Definition at line 66 of file SLBackground.h.

_textureOnlyProgram

SLGLProgram* SLBackground::_textureOnlyProgram = nullptr

private

Definition at line 72 of file SLBackground.h.

_vao

SLGLVertexArray SLBackground::_vao

private

OpenGL Vertex Array Object for drawing.

Definition at line 70 of file SLBackground.h.

---

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

• SLBackground.h
• SLBackground.cpp