Agfdhyk

I want to translate and scale a rectangle to specific coordinates. At this time I have to scale the rectangle only in the y plane. The translation works well, I have problems with the scaling, the rectangle is not placed at the right position. I tried to apply another solutions I found here and in another posts in stack overflow without success. This should be very easy, but I can't find the solution. I become from my source the top, bottom, left and right coordinates.
This is a part of the code.
Vertex and Fragment Shader:

vertexShaderSource = "#version 150 n"

"in vec2 aPos;n"

"in vec4 aColor;n"

"uniform mat4 projection;n"

"uniform mat4 model;n"

"uniform bool isLine;n"

"out vec4 oColor;n"

"void main() {n"

"   gl_Position =  projection *  model * vec4(aPos, 0.0, 1.0);n"

"   oColor = aColor;n"

"}n";

fragmentShaderSource = "#version 150 n"

"in vec4 oColor;n"

"out vec4 outColor; n"

"void main() {n"

"     outColor = oColor;n"

"}n";

Vertices:

GLfloat vertices = {

    // positions                           //colors              //alpha

    coordsLine->lineRight, coordsLine->top, 0.8f, 0.498f, 0.1960f, 0.4f,   // top right

    coordsLine->lineRight, coordsLine->bottom, 0.8f, 0.498f, 0.1960f, 0.4f, // bottom right

    coordsLine->lineLeft, coordsLine->bottom, 0.8f, 0.498f, 0.1960f, 0.4f, // bottom left

    coordsLine->lineLeft, coordsLine->top, 0.8f, 0.498f, 00.1960f, 0.4f // top left

};

Projection:

projection = glm::ortho(0.f, (float)dev->GetWidth(),(float)dev->GetHeight(), 0.f,  0.f, 1.f);

projection = glm::scale(projection, glm::vec3(dev->GetXScale(), dev->GetYScale(), 1.f));

Before the render loop:

tempLineLeft = coordsLine->lineLeft;

tempLineTop = coordsLine->top;lineHeight = coordsLine->bottom - coordsLine->top;

sourceLineMiddleHeight =(coordsLine->bottom - coordsLine->top) / 2.f;

sourceLineMiddleWidth = (coordsLine->lineRight - coordsLine->lineLeft) / 2.f;

I have to scale the projection to a device. This is working well without problems. Here is the translation and scaling, inside the render loop:

//Inside the Render Loop



if(tempLineLeft != coordsLine->lineLeft) {

    glUseProgram(shaderProgram);

    if(lineHeight != coordsLine->bottom - coordsLine->top) {

        destinationLineMiddleHeight = (coordsLine->bottom - coordsLine->top) / 2.f;

        scaleY = (coordsLine->bottom - coordsLine->top) / lineHeight;

        model = glm::translate(model, glm::vec3(coordsLine->lineLeft - tempLineLeft, coordsLine->top - tempLineTop, 0.f));

        model = glm::scale(model, glm::vec3(1.f, scaleY, 1.f));

        model = glm::translate(model, glm::vec3(0.f, destinationLineMiddleHeight, 0.f));



        }

        else {

            model = glm::translate(model, glm::vec3(0.f, destinationLineMiddleHeight, 0.f));



        }



    }

if(lineHeight != coordsLine->bottom - coordsLine->top)

    lineHeight = coordsLine->bottom - coordsLine->top;

tempLineLeft = coordsLine->lineLeft;

tempLineTop = coordsLine->top;

sourceLineMiddleHeight =(coordsLine->bottom - coordsLine->top) / 2.f;

sourceLineMiddleWidth = (coordsLine->lineRight - coordsLine->lineLeft) / 2.f;



glEnable (GL_BLEND);

glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);



glUseProgram(shaderProgram);

glBindVertexArray(VAO);

glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);

EDIT:
The real problem is the following: when I scale the object, it is jumping upwards/downwards, I have to translate it back to the target coordinates, and this doesn't works. I take some pictures, maybe it's clear what I'm meaning:
Object witouth Scale:

Object scaled:

This should be a trivial problem, I cann't find an equation to solve that.