Question

well I think I know what the problem is. I am just having a hard time debugging it. I am working with the directx api and I am trying to generate a plane along the x and z axis according to a book I have. The problem is when I am creating my indices. I think I am setting values out of the bounds of the indices array. I am just having a hard time figuring out what I did wrong. I am unfamiliar with the this method of generating a plane. so its a little difficult for me. below is my code. Take emphasis on the indices loop.

[edit]
Ive been reviewing it. This is how the indices works

 int curVertex = x + (z * NUM_VERTSX);

This always gets the beginning vertices. so say we have 17 vertices on the x axis and 17 vertices on the z axis and we are on the first loop of the x and z axis

curVertx = 0 + (0 * 17)
curVertx = 0 + 0 = 0

say we are on the first loop of the z axis and second loop of the x axis

curVertx = 1 + (0 * 17)
curVertx = 1+ 0 = 1

indices[curIndex] = curVertex;
            indices[curIndex + 1] = curVertex + NUM_VERTSX;
            indices[curIndex + 2] = curVertex + 1;

            indices[curIndex + 3] = curVertex + 1;
            indices[curIndex + 4] = curVertex + NUM_VERTSX;
            indices[curIndex + 5] = curVertex + NUM_VERTSX + 1;

if we are on the first

loop indices[curIndex] = curVertex;

this equals the first vertex = 0.

indices[curIndex + 1] = curVertex + NUM_VERTSX;

this equals the second row vertices (its always the vertices below the starting vertices

x x x x

[x] x x x

#include "MyGame.h"
//#include "CubeVector.h"
/* This code sets a projection and shows a turning cube. What has been added is the project, rotation and
a rasterizer to change the rasterization of the cube. The issue that was going on was something with the effect file
which was causing the vertices not to be rendered correctly.*/
typedef struct 
{
    ID3D10Effect* pEffect;
    ID3D10EffectTechnique* pTechnique;

    //vertex information
    ID3D10Buffer* pVertexBuffer;
    ID3D10Buffer* pIndicesBuffer;
    ID3D10InputLayout* pVertexLayout;

    UINT numVertices;
    UINT numIndices;
}ModelObject;

ModelObject modelObject;
// World Matrix
D3DXMATRIX                  WorldMatrix;
// View Matrix
D3DXMATRIX                  ViewMatrix;
// Projection Matrix
D3DXMATRIX                  ProjectionMatrix;
ID3D10EffectMatrixVariable* pProjectionMatrixVariable = NULL;

//grid information
#define NUM_COLS 16
#define NUM_ROWS 16

#define CELL_WIDTH 32
#define CELL_HEIGHT 32

#define NUM_VERTSX (NUM_COLS + 1)
#define NUM_VERTSY (NUM_ROWS + 1)




bool MyGame::InitDirect3D()
{
    if(!DX3dApp::InitDirect3D())
    {
        return false;
    }

    D3D10_RASTERIZER_DESC rastDesc;
    rastDesc.FillMode = D3D10_FILL_WIREFRAME;
    rastDesc.CullMode = D3D10_CULL_FRONT;
    rastDesc.FrontCounterClockwise = true;
    rastDesc.DepthBias = false;
    rastDesc.DepthBiasClamp = 0;
    rastDesc.SlopeScaledDepthBias = 0;
    rastDesc.DepthClipEnable = false;
    rastDesc.ScissorEnable = false;
    rastDesc.MultisampleEnable = false;
    rastDesc.AntialiasedLineEnable = false;

    ID3D10RasterizerState *g_pRasterizerState;
    mpD3DDevice->CreateRasterizerState(&rastDesc, &g_pRasterizerState);
    mpD3DDevice->RSSetState(g_pRasterizerState);

    // Set up the World Matrix
    D3DXMatrixIdentity(&WorldMatrix);
    D3DXMatrixLookAtLH(&ViewMatrix, new D3DXVECTOR3(0.0f, 10.0f, -20.0f), new D3DXVECTOR3(0.0f, 0.0f, 0.0f), new D3DXVECTOR3(0.0f, 1.0f, 0.0f));
    // Set up the projection matrix
    D3DXMatrixPerspectiveFovLH(&ProjectionMatrix, (float)D3DX_PI * 0.5f, (float)mWidth/(float)mHeight, 0.1f, 100.0f);

    if(!CreateObject())
    {
        return false;
    }

    return true;
}

//These are actions that take place after the clearing of the buffer and before the present
void MyGame::GameDraw()
{

    static float rotationAngle = 0.0f;

    // create the rotation matrix using the rotation angle
    D3DXMatrixRotationY(&WorldMatrix, rotationAngle);
    rotationAngle += (float)D3DX_PI * 0.0f;

    // Set the input layout
    mpD3DDevice->IASetInputLayout(modelObject.pVertexLayout);

    // Set vertex buffer
    UINT stride = sizeof(VertexPos);
    UINT offset = 0;
    mpD3DDevice->IASetVertexBuffers(0, 1, &modelObject.pVertexBuffer, &stride, &offset);
    mpD3DDevice->IASetIndexBuffer(modelObject.pIndicesBuffer, DXGI_FORMAT_R32_UINT, 0);

    // Set primitive topology
    mpD3DDevice->IASetPrimitiveTopology(D3D10_PRIMITIVE_TOPOLOGY_TRIANGLELIST);

    // Combine and send the final matrix to the shader
    D3DXMATRIX finalMatrix = (WorldMatrix * ViewMatrix * ProjectionMatrix);
    pProjectionMatrixVariable->SetMatrix((float*)&finalMatrix);


    // make sure modelObject is valid


    // Render a model object
    D3D10_TECHNIQUE_DESC techniqueDescription;
    modelObject.pTechnique->GetDesc(&techniqueDescription);

    // Loop through the technique passes
    for(UINT p=0; p < techniqueDescription.Passes; ++p)
    {
        modelObject.pTechnique->GetPassByIndex(p)->Apply(0);

        // draw the cube using all 36 vertices and 12 triangles
        mpD3DDevice->DrawIndexed(modelObject.numIndices,0,0);
    }
}

//Render actually incapsulates Gamedraw, so you can call data before you actually clear the buffer or after you 
//present data
void MyGame::Render()
{
    DX3dApp::Render();
}

bool MyGame::CreateObject()
{
    VertexPos vertices[NUM_VERTSX * NUM_VERTSY];
    for(int z=0; z < NUM_VERTSY; ++z)
    {
        for(int x = 0; x < NUM_VERTSX; ++x)
        {
            vertices[x + z * NUM_VERTSX].pos.x = (float)x * CELL_WIDTH;
            vertices[x + z * NUM_VERTSX].pos.z = (float)z * CELL_HEIGHT;

            vertices[x + z * NUM_VERTSX].pos.y = 0.0f;

            vertices[x + z * NUM_VERTSX].color = D3DXVECTOR4(1.0, 0.0f, 0.0f, 0.0f);
        }
    }

    DWORD indices[NUM_VERTSX * NUM_VERTSY];
    int curIndex = 0;

    for(int z=0; z < NUM_ROWS; ++z)
    {
        for(int x = 0; x < NUM_COLS; ++x)
        {
            int curVertex = x + (z * NUM_VERTSX);
            indices[curIndex] = curVertex;
            indices[curIndex + 1] = curVertex + NUM_VERTSX;
            indices[curIndex + 2] = curVertex + 1;

            indices[curIndex + 3] = curVertex + 1;
            indices[curIndex + 4] = curVertex + NUM_VERTSX;
            indices[curIndex + 5] = curVertex + NUM_VERTSX + 1;

            curIndex += 6;
        }
    }



    //Create Layout
    D3D10_INPUT_ELEMENT_DESC layout[] = {
        {"POSITION",0,DXGI_FORMAT_R32G32B32_FLOAT, 0 , 0, D3D10_INPUT_PER_VERTEX_DATA, 0},
        {"COLOR",0,DXGI_FORMAT_R32G32B32A32_FLOAT, 0 , 12, D3D10_INPUT_PER_VERTEX_DATA, 0}
    };

    UINT numElements = (sizeof(layout)/sizeof(layout[0]));
    modelObject.numVertices = sizeof(vertices)/sizeof(VertexPos);

    //Create buffer desc
    D3D10_BUFFER_DESC bufferDesc;
    bufferDesc.Usage = D3D10_USAGE_DEFAULT;
    bufferDesc.ByteWidth = sizeof(VertexPos) * modelObject.numVertices;
    bufferDesc.BindFlags = D3D10_BIND_VERTEX_BUFFER;
    bufferDesc.CPUAccessFlags = 0;
    bufferDesc.MiscFlags = 0;

    D3D10_SUBRESOURCE_DATA initData;
    initData.pSysMem = vertices;
    //Create the buffer

    HRESULT hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pVertexBuffer);
    if(FAILED(hr))
        return false;

    modelObject.numIndices = sizeof(indices)/sizeof(DWORD);

    bufferDesc.ByteWidth = sizeof(DWORD) * modelObject.numIndices;
    bufferDesc.BindFlags = D3D10_BIND_INDEX_BUFFER;

    initData.pSysMem = indices;

    hr = mpD3DDevice->CreateBuffer(&bufferDesc, &initData, &modelObject.pIndicesBuffer);
    if(FAILED(hr))
        return false;


    /////////////////////////////////////////////////////////////////////////////
    //Set up fx files
    LPCWSTR effectFilename = L"effect.fx";
    modelObject.pEffect = NULL;

     hr = D3DX10CreateEffectFromFile(effectFilename,
        NULL,
        NULL,
        "fx_4_0",
        D3D10_SHADER_ENABLE_STRICTNESS,
        0,
        mpD3DDevice,
        NULL,
        NULL,
        &modelObject.pEffect,
        NULL,
        NULL);

    if(FAILED(hr))
        return false;

    pProjectionMatrixVariable = modelObject.pEffect->GetVariableByName("Projection")->AsMatrix();
    //Dont sweat the technique. Get it!
    LPCSTR effectTechniqueName = "Render";

    modelObject.pTechnique = modelObject.pEffect->GetTechniqueByName(effectTechniqueName);
    if(modelObject.pTechnique == NULL)
        return false;


    //Create Vertex layout
    D3D10_PASS_DESC passDesc;
    modelObject.pTechnique->GetPassByIndex(0)->GetDesc(&passDesc);

    hr = mpD3DDevice->CreateInputLayout(layout, numElements,
        passDesc.pIAInputSignature,
        passDesc.IAInputSignatureSize,
        &modelObject.pVertexLayout);
    if(FAILED(hr))
        return false;

    return true;
}

Answer 1

Your indices array contains 6 entries per ‘cell’ (since you’re drawing two triangles for each), therefore it should be declared as

DWORD indices[NUM_ROWS * NUM_COLS * 6]

The error you get tells you, that you write outside the boundaries of indices, this is usually either a hint towards a wrong declaration (or a wrong index calculation).