# dx9 tutorial help

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I am able to draw a triangular pyramid to the screen, I am working with the directxtutorial.com web site. I really like this tutorial. I want to draw 20 triangular pyramids to the screen. Here is the code I am working with.
        { -1.0f, -1.0f, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -1.0f, 1.0f,-1.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ 1.0f, 1.0f, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ 1.0f, -1.0f, -1.0f, D3DCOLOR_XRGB(0, 0, 255), },


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Is this a thread for the 'Announcements' section? Or are you asking us how you might go about drawing 20 pyramids to the screen?

Stitchs.

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I want to know how to draw 20 triangular pyramids to the screen

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I want to know how to draw 20 triangular pyramids to the screen

Repeat the code for 1 pyramids 20 times, but of set each one by x (otherwise they will be drawn on top of each other)?

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so I should use a for loop?

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Use a for-loop where for each increment, you change the coordinates so that each pyramid is drawn at a certain distance away from the last. This will put them into a single row or column of pyrmaids.

If you wanted a pattern, try using a second for-loop nested in your first. The first can move the pyramids along the X-axis, then the second moves them on the Y-axis. This results in, for example. five triangles being drawn in a column, inner loop exits to outer loop, column start moves to the right. This is repeated until you have 20 drawn on the screen, in 4 columns of 5 pyramids.

Regards,

Stitchs.

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am I on the right track with this code
        { x, -x, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -x, x,-1.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ x, x, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ x, -x, -1.0f, D3DCOLOR_XRGB(0, 0, 255), },


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am I on the right track with this code

        { x, -x, 0.0f, D3DCOLOR_XRGB(0, 255, 0), },
{ -x, x,-1.0f, D3DCOLOR_XRGB(0, 0, 255), },
{ x, x, 0.0f, D3DCOLOR_XRGB(255, 0, 0), },
{ x, -x, -1.0f, D3DCOLOR_XRGB(0, 0, 255), },


Well,yes and no, the first 3 floats are X,Y and Z (i assume, sorry), this (im pretty sure) will create them in a diagonal pattern

for(float i; i <= (20*32); i+=32.0f){

...[code]
{ -i, -1.0f, 0.0f,d3dcolor_xrgb(0,255,0),}
[code]
....

}


the loop increases by 32 each itteration, thus, the spacing between the pyramid will be 32px on the x axis

bare in mind its only an example :)

hopw that helps

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You'll want to create a static model of your pyramid. That means no variables in the pyramid declaration. Once that's done you use a transform to place the pyramid where you want to render it in the world.

This process is described in lesson 5 on the site you're using.

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Posted 13 April 2013 - 04:03 PM

You'll want to create a static model of your pyramid. That means no variables in the pyramid declaration. Once that's done you use a transform to place the pyramid where you want to render it in the world.

well I  have read the lesson 5 several times, I understand how to scale and rotate an object but don't understand of how to transform an object. what I want to do is draw several objects to the screen. I am able to draw a single object to the center of the screen. let me know if  you need more explanation. I am trying to ask more intelligent questions.

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To draw it more than once you just change the transform and then draw it again.

D3DXMatrixTranslation()

should be what you're looking for.

You have to reset the world matrix for every time you render the model. That means set the matrix to the identity, then do your scaling, rotation and translation -> every time. Once the matrix is set just do your draw call.

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well I have reread session 5 and 7 but I am still stuck I will do more research. thanks for all the help. should I post code?

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should I post code?

yep!

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ok here  is the code I am working with

// this is the function used to render a single frame
void

render_frame(void)
{
d3ddev->Clear(0,

NULL, D3DCLEAR_TARGET, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
d3ddev->Clear(0,

NULL, D3DCLEAR_ZBUFFER, D3DCOLOR_XRGB(0, 0, 0), 1.0f, 0);
d3ddev->BeginScene();
d3ddev->SetFVF(

CUSTOMFVF);

// set the view transform

D3DXMATRIX matView; // the view transform matrix
D3DXMatrixLookAtLH(&matView,
&

D3DXVECTOR3 (0.0f, 8.0f, 25.0f), // the camera position
&

D3DXVECTOR3 (0.0f, 0.0f, 0.0f), // the look-at position
&

D3DXVECTOR3 (0.0f, 1.0f, 0.0f)); // the up direction
d3ddev->SetTransform(

D3DTS_VIEW, &matView); // set the view transform to matView

// set the projection transform

D3DXMATRIX matProjection; // the projection transform matrix
D3DXMatrixPerspectiveFovLH(&matProjection,

D3DXToRadian(45), // the horizontal field of view
(

FLOAT)SCREEN_WIDTH / (FLOAT)SCREEN_HEIGHT, // aspect ratio
1.0f,

// the near view-plane
100.0f);

// the far view-plane
d3ddev->SetTransform(

D3DTS_PROJECTION, &matProjection); // set the projection

// set the world transform

static float index = 0.0f; index+=0.03f; // an ever-increasing float value

D3DXMATRIX matRotateY; // a matrix to store the rotation for each triangle
D3DXMatrixRotationY(&matRotateY, index);

// the rotation matrix
d3ddev->SetTransform(

D3DTS_WORLD, &(matRotateY)); // set the world transform

// select the vertex buffer to display
d3ddev->SetStreamSource(0, v_buffer, 0,

sizeof(CUSTOMVERTEX));
d3ddev->SetIndices(i_buffer);

// draw the Hypercraft
d3ddev->DrawIndexedPrimitive(

D3DPT_TRIANGLELIST, 0, 0, 10, 0, 6);
d3ddev->EndScene();
d3ddev->Present(

NULL, NULL, NULL, NULL);
}


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D3DXMATRIX matRotateY, matTranslate, matWorld;

//generate the rotation
D3DXMatrixRotationY(&matRotateY, index);

//generate the translation
D3DXMatrixTranslation(&matTranslate, x, y, z);

//concatenate them into the world matrix - if you add scaling then it comes first (world = scale * rot * trans)
matWorld = matRotate * matTranslate;

d3ddev->SetTransform(D3DTS_WORLD, &matWorld);


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I am able to draw the triangular pyramid in the upper left corner of the screen. I just want to draw two pyramids to the screen. Thanks for all the help khatharr.

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Set the model, set the matrix, draw, set the new matrix, draw.

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cool thanks, I am working on putting a tail fin on my space ship, as per the tutorial