Hi,

I am writing a school project of mine, drawing different circuits transfer function (voltage transfer and phase). I wrote my code in C++ msvc Win32 native app with D3D9 and it works just fine. Only problem is, somehow rendering misses every second line, actually not missing but barely drawing it, and it's very frustrating. What could be the problem?

[attachment=21163:d3d9.png]

void render(void)
	{
		D3DXMATRIX world, scale, translate, center;
		D3DXMATRIX view;
		D3DXMATRIX final;
		H transfer;
		LPVOID lpVertices;
		DWORD vertexCount;
		VERTEX vertex;
		double xScale, yScale;
		double marginsWidthH, marginsWidthV;

		// ha nem létezik az áramkör
		if (lpcirc == NULL)
			return;

		// elkérjük a transzfer karakterisztikát
		transfer = lpcirc->getH();
		// ha üres
		if (transfer.count == 0)
			return;

		// margó szélessége egységre nézve
		marginsWidthH = BODE_WINDOW_MARGIN / (WindowWidth / 2.0f);
		marginsWidthV = BODE_WINDOW_MARGIN / (WindowHeight / 2.0f);

		// Identitás mátrix mindenre
		D3DXMatrixIdentity(&world);
		D3DXMatrixIdentity(&scale);
		D3DXMatrixIdentity(&center);
		D3DXMatrixIdentity(&translate);
		// Identitás mátrix a nézetre
		D3DXMatrixIdentity(&view);

		/// =========================================
		/// Pár adat, amit el?re ki kell számolni
		/// =========================================
		// min, max frekvenciakitev?
		double pwMin = transfer.fs[0].pw;
		double pwMax = transfer.fs[transfer.count - 1].pw;
		// min, max átvitel
		double fsMin = 10.0 * log(ABS2(transfer.minFs.Zu2_u1));
		double fsMax = 10.0 * log(ABS2(transfer.maxFs.Zu2_u1));
		// min, max fázis
		double phMin = ARG(transfer.minPh.Zu2_u1);
		double phMax = ARG(transfer.maxPh.Zu2_u1);

		/// =========================================
		/// Transzferkarakterisztika
		/// =========================================

		// egységre leskálázva, margó beleszámít
		xScale = (1.0 - marginsWidthH) / (pwMax - pwMin);
		// abszolútérték skálája egységre nézve
		yScale = (1.0 - marginsWidthV) / (fsMax - fsMin);

		// töröljük a képerny?t
		lpd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET, 0xFFDDDDDD, 1.0f, 0);
		// kezd?dhet a rajzolás
		lpd3dDevice->BeginScene();

		// betoljuk a függvényt az origóba
		D3DXMatrixTranslation(&center, (float) -pwMin, (float) -fsMax, 0.0);
		// megskálázzuk, hogy a diagramunk elférjen az ablakban
		D3DXMatrixScaling(&scale, 2.0f * (float) xScale, 2.0f * (float) yScale, 1.0f);
		// eltoljuk a függvényt a -1.0-ba x tengelyen (ablak bal széle) + margó
		// y tengelyen 1.0 (ablak teteje ) - margó
		D3DXMatrixTranslation(&translate, -1.0f + (float) marginsWidthH, 1.0f - (float) marginsWidthV, 0.0f);

		// ered? mátrix
		final = world * center * scale * translate;
		// transzformációk beállítása
		lpd3dDevice->SetTransform(D3DTS_WORLD, &final);
		lpd3dDevice->SetTransform(D3DTS_VIEW, &view);

		/// =========================================
		/// Transzferkarakterisztika rajzolása
		/// =========================================

		// elkérjük a vertex buffert
		lpd3dVertexBuffer->Lock(0, BODE_VERTEXBUFFER_SIZE, (LPVOID*) &lpVertices, 0);
		// egyel?re nincs pont
		vertexCount = 0;

		// végigmegyünk az összes ponton az átviteli függvényben
		for (int i = 0; i < transfer.count; i++)
		{
			vertex.color = 0x66000000;
			vertex.x = (float) transfer.fs[i].pw;
			vertex.y = (float) (10.0 * log(ABS2(transfer.fs[i].Zu2_u1)));
			vertex.z = 1.0f;

			// bemásoljuk a videómemóriába
			memcpy(((VERTEX*) lpVertices + vertexCount), &vertex, sizeof(VERTEX));
			// egyel több pont a halmazban
			vertexCount++;
		}

		// feloldjuk a videómemóriát
		lpd3dVertexBuffer->Unlock();

		lpd3dDevice->SetStreamSource(0, lpd3dVertexBuffer, 0, sizeof(VERTEX));
		lpd3dDevice->SetFVF(BODE_D3DFVF);
		lpd3dDevice->DrawPrimitive(D3DPT_LINESTRIP, 0, vertexCount - 1);

		/// =========================================
		/// Transzferkarakterisztika VÉGE
		/// =========================================

		// Identitás mátrix mindenre
		D3DXMatrixIdentity(&world);
		D3DXMatrixIdentity(&scale);
		D3DXMatrixIdentity(&center);
		D3DXMatrixIdentity(&translate);
		// Identitás mátrix a nézetre
		D3DXMatrixIdentity(&view);

		/// =========================================
		/// Fázismenet
		/// =========================================

		// egységre leskálázva, margó beleszámít
		xScale = (1.0 - marginsWidthH) / (pwMax - pwMin);
		// abszolútérték skálája egységre nézve
		yScale = (1.0 - marginsWidthV) / (phMax - phMin);

		// betoljuk a függvényt az origóba
		D3DXMatrixTranslation(&center, (float) -pwMin, (float) -phMax, 0.0f);
		// megskálázzuk, hogy a diagramunk elférjen az ablakban
		D3DXMatrixScaling(&scale, 2.0f * (float) xScale, 2.0f * (float) yScale, 1.0f);
		// eltoljuk a függvényt a -1.0-ba x tengelyen (ablak bal széle) + margó
		// y tengelyen 1.0 (ablak teteje ) - margó
		D3DXMatrixTranslation(&translate, -1.0f + (float) marginsWidthH, 1.0f - (float) marginsWidthV, 0.0f);

		// ered? mátrix
		final = world * center * scale * translate;
		// transzformációk beállítása
		lpd3dDevice->SetTransform(D3DTS_WORLD, &final);
		lpd3dDevice->SetTransform(D3DTS_VIEW, &view);

		/// =========================================
		/// Fázismenet rajzolása
		/// =========================================

		// elkérjük a vertex buffert
		lpd3dVertexBuffer->Lock(0, BODE_VERTEXBUFFER_SIZE, (LPVOID*) &lpVertices, 0);
		// egyel?re nincs pont
		vertexCount = 0;

		// végigmegyünk az összes ponton az átviteli függvényben
		for (int i = 0; i < transfer.count; i++)
		{
			vertex.color = 0xFFFF0000;
			vertex.x = (float) transfer.fs[i].pw;
			vertex.y = (float) ARG(transfer.fs[i].Zu2_u1);
			vertex.z = 1.0f;

			// bemásoljuk a videómemóriába
			memcpy(((VERTEX*) lpVertices + vertexCount), &vertex, sizeof(VERTEX));
			// egyel több pont a halmazban
			vertexCount++;
		}

		// feloldjuk a videómemóriát
		lpd3dVertexBuffer->Unlock();

		lpd3dDevice->SetStreamSource(0, lpd3dVertexBuffer, 0, sizeof(VERTEX));
		lpd3dDevice->SetFVF(BODE_D3DFVF);
		lpd3dDevice->DrawPrimitive(D3DPT_LINESTRIP, 0, vertexCount - 1);

		/// =========================================
		/// Fázismenet VÉGE
		/// =========================================


		// vége a rajzolásnak
		lpd3dDevice->EndScene();
		// mutassa meg az eredményt
		lpd3dDevice->Present(NULL, NULL, NULL, NULL);
	}

lpd3dDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);

Maybe adding this line before DrawPrimite will be helpful.

Please, share the result.

That may be the VERY common mistake that you forget about the window borders and top bar when you specify dimensions. If you make a window 800x600 pixels large, you cannot use this values also as backbuffer dimensions, because the client area will be less than 800x600 (depends on the Windows version and settings). Because then DirectX performs some stretching for you, which will result in errors similar to yours (as it tries to display a 800x600 image on a lets say 784x578 large area).

You must use the AdjustWindowRect function to find the window dimensions required for a particular client area size. (Or the inverse, using for example GetClientRect, but AdjustWindowRect is IMHO better because it allows you to have a specific backbuffer size rather than window size.)

lpd3dDevice->SetRenderState(D3DRS_CULLMODE, D3DCULL_NONE);

Maybe adding this line before DrawPrimite will be helpful.

Please, share the result.

Unfortunately it didn't work, I also tried other Render switches with no solution.

You must use the AdjustWindowRect function to find the window dimensions required for a particular client area size.

So what you say is when DirectX is done converting everything to pixel, in the processing of this little stretch some pixels get faded because their size becomes less than 1?

I don't know what kind of filtering (if any) it's doing during this process. But the result almost never is satisfying ;)

I also don't know whether it really is the source of your problem, that was just a tip. How do you create your window and how do you set the backbuffer dimensions?

Well Tom,

You saved me , setting buffer sizes to Client area solved the problem, Thanks.

Strange is I have another project, and there is no problem with such thing, actually I copied all the initialization from there.

Here is the result of your contribution:

[attachment=21178:Screenshot (3).png]

Strange is I have another project, and there is no problem with such thing, actually I copied all the initialization from there.

There most certainly is the very same problem, it just may be less visible (almost invisible).

In more complex graphics, like in a normal game, you probably wouldn't notice at all that few rows and columns of pixels are badly displayed.

And also in a project like this one, where you have 1 pixel thin lines, you may be lucky - for example in the screenshot you showed here, if the errors were not in the horizontal zone, but in the slope, do you think you would notice it?

if the errors were not in the horizontal zone, but in the slope, do you think you would notice it?

makes sense :D