Messages

1

Graphics / Re: How to draw a Shape with Shader to a Rendertexture ?

« on: November 30, 2019, 08:43:35 pm »

I can draw the shader to a RenderTexture now, but even if the base circle shape is set to transparent
i dont get transparent edges but black ones.

circle.setFillColor(sf::Color::Transparent);

if i set

sf::Color

to

{1,1,1,0}

i get a white border.

Why is this color picked up when its 100% transparent??


Example:

#include <SFML/Graphics.hpp>
#include <iostream>

#pragma region Shader
        const char VertexShader[] =
        "void main()"
        "{"
        "gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;"
        "gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;"
        "gl_FrontColor = gl_Color;"
        "}";

        const char RadialGradient[] =
        "uniform vec4 color;"
        "uniform vec2 center;"
        "uniform float radius;"
        "uniform float expand;"
        "uniform float windowHeight;"
        "void main(void)"
        "{"
        "vec2 centerFromSfml = vec2(center.x, windowHeight - center.y);"
        "vec2 p = (gl_FragCoord.xy - centerFromSfml) / radius;"
        "float r = sqrt(dot(p, p));"
        "if (r < 1.0)"
        "{"
        "gl_FragColor = mix(color, gl_Color, (r - expand) / (1 - expand));"
        "}"
        "else"
        "{"
        "gl_FragColor = gl_Color;"
        "}"
        "}";
#pragma endregion

int main()
{
        sf::RenderWindow window(sf::VideoMode(800, 600), "Radial Gradient", sf::Style::Default);
        sf::Event event;

        sf::CircleShape circle;
        sf::Shader shader;

        circle.setRadius(50.f);
        circle.setOrigin(circle.getRadius(), circle.getRadius());
        circle.setPosition(sf::Vector2f(window.getSize()) / 2.f);
        circle.setFillColor(sf::Color::Transparent);

        shader.loadFromMemory(VertexShader, RadialGradient);
        shader.setUniform("windowHeight", static_cast<float>(window.getSize().y)); // needs to be set whenever windowsize changes

        sf::RenderTexture RT;
        RT.create(800, 600);
        RT.clear(sf::Color::Transparent);
        sf::Sprite SP;
        SP.setTexture(RT.getTexture(), true);

        //--------------------------------------------------------------------------------------------------------------------
        sf::Texture TX_BG;
        TX_BG.loadFromFile("img/bg.png");
        sf::Sprite SP_Backgr;
        SP_Backgr.setTexture(TX_BG);
        SP_Backgr.setPosition(sf::Vector2f(0, 0));
        SP_Backgr.setOrigin(sf::Vector2f(0, 0));
        //--------------------------------------------------------------------------------------------------------------------

        sf::RenderStates states;
        states.shader = &shader;
        states.blendMode = sf::BlendAlpha;


        while (window.isOpen())
        {
                while (window.pollEvent(event))
                {
                        if (event.type == sf::Event::Closed) { window.close(); }
                        if (event.type == sf::Event::KeyPressed)
                        {
                                if (event.key.code == sf::Keyboard::Num1) { states.blendMode = sf::BlendAlpha; std::cout << "BlendAlpha" << std::endl; }
                                if (event.key.code == sf::Keyboard::Num2) { states.blendMode = sf::BlendAdd; std::cout << "BlendAdd" << std::endl; }
                                if (event.key.code == sf::Keyboard::Num3) { states.blendMode = sf::BlendMultiply; std::cout << "BlendMultiply" << std::endl; }
                                if (event.key.code == sf::Keyboard::Num4) { states.blendMode = sf::BlendNone; std::cout << "BlendNone" << std::endl; }
                        }
                }

                sf::Vector2i MG = sf::Mouse::getPosition(window);                       // Mouse Global
                sf::Vector2f ML = window.mapPixelToCoords(MG);                          // Mouse Local

                circle.setPosition(ML);
               
                shader.setUniform("color", sf::Glsl::Vec4(1, 0, 0, 1.f));
                shader.setUniform("center", circle.getPosition());
                shader.setUniform("radius", circle.getRadius());
                shader.setUniform("expand", 0.f);

                //RT.clear(sf::Color::Transparent);
                RT.draw(circle, states);
                RT.display();

                window.clear();
                window.draw(SP_Backgr);
                window.draw(SP);
                window.display();

                //window.draw(circle, &shader);
                //window.display();
        }

        return EXIT_SUCCESS;
}

2

Graphics / Re: How to draw a Shape with Shader to a Rendertexture ?

« on: November 28, 2019, 12:24:04 am »

Minimal example which actually works... 

#include <SFML/Graphics.hpp>

#pragma region Shader
        const char VertexShader[] =
        "void main()"
        "{"
        "gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;"
        "gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;"
        "gl_FrontColor = gl_Color;"
        "}";

        const char RadialGradient[] =
        "uniform vec4 color;"
        "uniform vec2 center;"
        "uniform float radius;"
        "uniform float expand;"
        "uniform float windowHeight;"
        "void main(void)"
        "{"
        "vec2 centerFromSfml = vec2(center.x, windowHeight - center.y);"
        "vec2 p = (gl_FragCoord.xy - centerFromSfml) / radius;"
        "float r = sqrt(dot(p, p));"
        "if (r < 1.0)"
        "{"
        "gl_FragColor = mix(color, gl_Color, (r - expand) / (1 - expand));"
        "}"
        "else"
        "{"
        "gl_FragColor = gl_Color;"
        "}"
        "}";
#pragma endregion

int main()
{
        sf::RenderWindow window(sf::VideoMode(800, 600), "Radial Gradient", sf::Style::Default);
        sf::Event event;
        sf::CircleShape circle;
        sf::Shader shader;

        circle.setRadius(100.f);
        circle.setOrigin(circle.getRadius(), circle.getRadius());
        circle.setPosition(sf::Vector2f(window.getSize()) / 2.f);
        circle.setFillColor(sf::Color::Transparent);

        shader.loadFromMemory(VertexShader, RadialGradient);
        shader.setUniform("windowHeight", static_cast<float>(window.getSize().y)); // needs to be set whenever window changes

        sf::RenderTexture RT;
        RT.create(800, 600);
        sf::Sprite SP;
        SP.setTexture(RT.getTexture(), true);

        while (window.isOpen())
        {
                while (window.pollEvent(event)) { if (event.type == sf::Event::Closed){ window.close(); }}
               
                shader.setUniform("color", sf::Glsl::Vec4(0, 0, 1, 1));
                shader.setUniform("center", circle.getPosition());
                shader.setUniform("radius", circle.getRadius());
                shader.setUniform("expand", 0.f);

                RT.clear();
                RT.draw(circle, &shader);
                RT.display();

                window.clear();
                window.draw(SP);
                window.display();

                //window.draw(circle, &shader);
                //window.display();
        }

        return EXIT_SUCCESS;
}

3

Graphics / Re: How to draw a Shape with Shader to a Rendertexture ?

« on: November 25, 2019, 02:34:38 am »

This is the shader i use:

const char VertexShader[] =
        "void main()"
        "{"
        "gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;"
        "gl_TexCoord[0] = gl_TextureMatrix[0] * gl_MultiTexCoord0;"
        "gl_FrontColor = gl_Color;"
        "}";

        const char RadialGradient[] =
        "uniform vec4 color;"
        "uniform vec2 center;"
        "uniform float radius;"
        "uniform float expand;"
        "uniform float windowHeight;"
        "void main(void)"
        "{"
        "vec2 centerFromSfml = vec2(center.x, windowHeight - center.y);"
        "vec2 p = (gl_FragCoord.xy - centerFromSfml) / radius;"
        "float r = sqrt(dot(p, p));"
        "if (r < 1.0)"
        "{"
        "gl_FragColor = mix(color, gl_Color, (r - expand) / (1 - expand));"
        "}"
        "else"
        "{"
        "gl_FragColor = gl_Color;"
        "}"
        "}";

Its from Github  https://github.com/SFML/SFML/wiki/Source:-Radial-Gradient-Shader

I think the shader is never completly transparent. But it fades out TO transparent.

When i render to the window i see the shader.
But its not rendered onto the RenderTexture

This is the part where i draw to RT:

brush.setFillColor(sf::Color::Transparent);
brush.setPosition(ML);
sf::Vector2i CTP = window.mapCoordsToPixel(ML); // ML = Mouse Local Coordinates
float multi = ZoomLevel / 100.f;
brush_shader.setUniform("color", sf::Glsl::Vec4(0, 0, 1, 1));
brush_shader.setUniform("center", sf::Vector2f(CTP.x, CTP.y));  // "center" uses Global Coordinates!!
brush_shader.setUniform("radius", brush.getRadius()* multi);
brush_shader.setUniform("expand", 0.25f);
//window.draw(brush);
//brush.setFillColor(ColorBrush);

states.shader = &brush_shader;

if (ToolNow == 0) // Eraser Brush
{
        states.blendMode = sf::BlendNone;
        if (LayerNR == 0) { RT_Layer0.draw(brush, states); RT_Layer0.display(); }
        if (LayerNR == 1) { RT_Layer1.draw(brush, states); RT_Layer1.display(); }
        if (LayerNR == 2) { RT_Layer2.draw(brush, states); RT_Layer2.display(); }
        if (LayerNR == 3) { RT_Layer3.draw(brush, states); RT_Layer3.display(); }
        if (LayerNR == 4) { RT_Layer4.draw(brush, states); RT_Layer4.display(); }
}
if (ToolNow != 0) // Standard Brush
{
        states.blendMode = sf::BlendAlpha;
        if (LayerNR == 0) { RT_Layer0.draw(brush, &brush_shader); RT_Layer0.display(); }  // Shader direct
        if (LayerNR == 1) { RT_Layer1.draw(brush, states); RT_Layer1.display(); }
        if (LayerNR == 2) { RT_Layer2.draw(brush, states); RT_Layer2.display(); }
        if (LayerNR == 3) { RT_Layer3.draw(brush, states); RT_Layer3.display(); }
        if (LayerNR == 4) { RT_Layer4.draw(brush, states); RT_Layer4.display(); }
}


...
window.draw(brush, &brush_shader); // <--- This works!

For testing i dont use "states" in "RT_Layer0" but the shader directly.

4

Graphics / How to draw a Shape with Shader to a Rendertexture ?

« on: November 24, 2019, 02:50:41 am »

Hello Forum,

I have a brush (CircleShape) and i can draw with it straight to a RenderTexture without any problems.
But now i want to have a Soft Brush like in Photoshop.

So i apply a radial gradient shader to that Brush Circle Shape.
For this i have to set the

brush.setFillColor(sf::Color::Transparent);

Now when i do this nothing gets drawn to the RenderTexture anymore although i do:

RT_Layer0.draw(brush, &brush_shader);
RT_Layer0.display();

Since i also do a

window.draw(brush, &brush_shader);

I can see the shader correctly applyd to the CircleShape brush.

Iam sure iam missing something here...

Thanks! 

5

Graphics / Re: How to draw a Shape to RenderTexture but like an Eraser?

« on: October 22, 2019, 09:25:09 pm »

It works! Thank you! 

6

Graphics / [SOLVED] How to draw a Shape to RenderTexture but like an Eraser?

« on: October 22, 2019, 07:34:01 pm »

Hello Forum,

I work on a little drawing tool.
Drawing works fine. But how do i erase with a shape?

I have a circle shape which is my brush.
If i set Alpha to zero. Nothing is drawn. Okay, makes sense.
But how can i use my "brush" to discard already drawn stuff??

Thanks!

7

General / Re: Best practise to: Smooth VertexArray data (from Mouse input)

« on: October 04, 2019, 05:14:03 am »

Okay. As it seems for now... The Chaikin algorithm would be the best i think.

Was looking online for some code but i could only find this .vb code.

https://www.codeproject.com/Articles/1093960/D-Polyline-Vertex-Smoothing
 

8

General / Best practise to: Smooth VertexArray data (from Mouse input)

« on: October 04, 2019, 02:14:10 am »

Hello forum,

I'am looking for a way to smooth some existing VertexArray data (x,y).
The data comes from user input via mouse or graphics tablet input.

Maybe somebody can point me into the right direction.
I think i cant implement this myself. So maybe there is some code out there that i can use in C++ ?

Thank you!

I've got this code already but it does not return proper x y coordinates:

void Smooth(sf::VertexArray& vertex)
{
        int n = vertex.getVertexCount();

        std::vector<int> r(n);
        std::vector<float> x;
        std::vector<float> y;

        for (int i = 0; i < n; i++)
        {
                x.emplace_back(vertex[i].position.x);
                y.emplace_back(vertex[i].position.y);

                std::cout << x[i] << " : " << y[i] << std::endl;
        }

        std::iota(r.begin(), r.end(), 0);

        float xm = std::accumulate(x.begin(), x.end(), 0.0) / x.size();
        float ym = std::accumulate(y.begin(), y.end(), 0.0) / y.size();
        float x2m = std::transform_reduce(r.begin(), r.end(), 0.0, std::plus<float>{}, [](float a) {return a * a; }) / r.size();
        float x3m = std::transform_reduce(r.begin(), r.end(), 0.0, std::plus<float>{}, [](float a) {return a * a * a; }) / r.size();
        float x4m = std::transform_reduce(r.begin(), r.end(), 0.0, std::plus<float>{}, [](float a) {return a * a * a * a; }) / r.size();

        float xym = std::transform_reduce(x.begin(), x.end(), y.begin(), 0.0, std::plus<float>{}, std::multiplies<float>{});
        xym /= fmin(x.size(), y.size());

        float x2ym = std::transform_reduce(x.begin(), x.end(), y.begin(), 0.0, std::plus<float>{}, [](float a, float b) { return a * a * b; });
        x2ym /= fmin(x.size(), y.size());

        float sxx = x2m - xm * xm;
        float sxy = xym - xm * ym;
        float sxx2 = x3m - xm * x2m;
        float sx2x2 = x4m - x2m * x2m;
        float sx2y = x2ym - x2m * ym;

        float b = (sxy * sx2x2 - sx2y * sxx2) / (sxx * sx2x2 - sxx2 * sxx2);
        float c = (sx2y * sxx - sxy * sxx2) / (sxx * sx2x2 - sxx2 * sxx2);
        float a = ym - b * xm - c * x2m;

        auto abc = [a, b, c](float xx) {
                return a + b * xx + c * xx*xx;
        };

        std::cout << "y = " << a << " + " << b << "x + " << c << "x^2" << std::endl;
        std::cout << " Input  Approximation" << std::endl;
        std::cout << " x   y     y1" << std::endl;
        //std::cout << sxx << std::endl;

        auto xit = x.cbegin();
        auto xend = x.cend();
        auto yit = y.cbegin();
        auto yend = y.cend();
        while (xit != xend && yit != yend) {
                printf("%2d %3d  %5.1f\n", xit, yit, abc(*xit));
                xit = std::next(xit);
                yit = std::next(yit);
        }
}

9

Window / Re: Making a window always on top

« on: November 08, 2016, 09:53:14 pm »

void makeWindowOnTop(sf::RenderWindow& window)
{
        HWND hwnd = window.getSystemHandle();
        SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, 0, 0, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
}