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Rotating texture coordinates to animate multi-textured flare

4 posts in this topic

I have a "flare" texture(.dds) and an alpha texture (.bmp). I'm trying to use these with multi-texturing to create a blended flare image. I then put the final image onto each face of a cube. So far, I have accomplished this. However, the next step is what I have trouble understanding. I want to rotate both textures at different rates to create a flare animation. In turn, I must map the animation to each face of the cube like before. When I run my program, the textures are rotating in a circle instead of rotating about their own axes

Here is a screen shot:
Clearly this is not what I wanted.

Basically what I am doing is this: I create two D3DXVECTOR2s to be used as offsets. One for both textures. I then rotate them a bit each frame(at different rates). Lastly, I add both offsets in the vertex shader, and store the results in the cooresponding members of the outVS structure like this:
OutputVS TerrainMultiTexVS(float3 posL : POSITION0,
float3 normalL : NORMAL0,
float2 tex0: TEXCOORD0)

//omitted code

outVS.tex0 = tex0 + gTexOffset;
outVS.tex1 = tex0 + gBlendOffset;

// Done--return the output.
return outVS;
Note how "tex0" is used in both additions. That is because "tex0" is the only set of texture coordinates that is fed into the vertex shader.

Again, I don't want them orbiting the center of the faces in a circle. I want them to simply rotate about their own axes. (which is of course the center of each face)

Here is some source code...

// this is from Vertex.h
struct VertexPNT
:pos(0.0f, 0.0f, 0.0f),
normal(0.0f, 0.0f, 0.0f),
tex0(0.0f, 0.0f){}
VertexPNT(float x, float y, float z,
float nx, float ny, float nz,
float u, float v):pos(x,y,z), normal(nx,ny,nz), tex0(u,v){}
VertexPNT(const D3DXVECTOR3& v, const D3DXVECTOR3& n, const D3DXVECTOR2& uv)
:pos(v),normal(n), tex0(uv){}
D3DXVECTOR3 normal;
static IDirect3DVertexDeclaration9* Decl;

// this is from Vertex.cpp
HR(gd3dDevice->CreateVertexDeclaration(VertexPNTElements, &VertexPNT::Decl));

// found in class definition
D3DXHANDLE mhTexOffset;
D3DXHANDLE mhBlendOffset;
D3DXVECTOR2 mTexOffset;
D3DXVECTOR2 mBlendOffset;
float angle_Tex;
float angle_Blend;


// found in constructor
angle_Tex = 0.0f;
angle_Blend = 0.0f;
mTexOffset = D3DXVECTOR2(0.0f, 0.0f);
mBlendOffset = D3DXVECTOR2(0.0f, 0.0f);

HR(D3DXCreateTextureFromFile(gd3dDevice, "flare.dds", &mTex));
HR(D3DXCreateTextureFromFile(gd3dDevice, "flarealpha.bmp", &mBlend));

void FlareCubeDemo::updateScene(float dt)
// Get snapshot of input devices.
// Check input.
if( gDInput->keyDown(DIK_W) )
mCameraHeight += 25.0f * dt;
if( gDInput->keyDown(DIK_S) )
mCameraHeight -= 25.0f * dt;
// Divide by 50 to make mouse less sensitive.
mCameraRotationY += gDInput->mouseDX() / 100.0f;
mCameraRadius += gDInput->mouseDY() / 25.0f;
// If we rotate over 360 degrees, just roll back to 0
if( fabsf(mCameraRotationY) >= 2.0f * D3DX_PI )
mCameraRotationY = 0.0f;
// Don't let radius get too small.
if( mCameraRadius < 5.0f )
mCameraRadius = 5.0f;
angle_Tex = 0.001;
angle_Blend = 0.005;
// The camera position/orientation relative to world space can
// change every frame based on input, so we need to rebuild the
// view matrix every frame with the latest changes.

mTexOffset += D3DXVECTOR2(-0.5f, -0.5f);
mBlendOffset += D3DXVECTOR2(-0.5f, -0.5f);
D3DXMatrixRotationZ(&Mt, angle_Tex);
D3DXMatrixRotationZ(&Mb, angle_Blend);
D3DXVec2TransformCoord(&mTexOffset, &mTexOffset, &Mt);
D3DXVec2TransformCoord(&mBlendOffset, &mBlendOffset, &Mb);

mTexOffset += D3DXVECTOR2(0.5f, 0.5f);
mBlendOffset += D3DXVECTOR2(0.5f, 0.5f);

void FlareCubeDemo::drawScene()
// Clear the backbuffer and depth buffer.
HR(gd3dDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0xffeeeeee, 1.0f, 0));
// Setup the rendering FX
HR(mFX->SetMatrix(mhWVP, &(mWorld*mView*mProj)));
D3DXMATRIX worldInvTrans;
D3DXMatrixInverse(&worldInvTrans, 0, &mWorld);
D3DXMatrixTranspose(&worldInvTrans, &worldInvTrans);
HR(mFX->SetMatrix(mhWorldInvTrans, &worldInvTrans));
HR(mFX->SetValue(mhLightVecW, &mLightVecW, sizeof(D3DXVECTOR3)));
HR(mFX->SetValue(mhDiffuseMtrl, &mDiffuseMtrl, sizeof(D3DXCOLOR)));
HR(mFX->SetValue(mhDiffuseLight, &mDiffuseLight, sizeof(D3DXCOLOR)));
HR(mFX->SetValue(mhAmbientMtrl, &mAmbientMtrl, sizeof(D3DXCOLOR)));
HR(mFX->SetValue(mhAmbientLight, &mAmbientLight, sizeof(D3DXCOLOR)));
HR(mFX->SetValue(mhSpecularLight, &mSpecularLight, sizeof(D3DXCOLOR)));
HR(mFX->SetValue(mhSpecularMtrl, &mSpecularMtrl, sizeof(D3DXCOLOR)));
HR(mFX->SetFloat(mhSpecularPower, mSpecularPower));
HR(mFX->SetMatrix(mhWorld, &mWorld));
HR(mFX->SetTexture(mhTex, mTex));
HR(mFX->SetTexture(mhBlend, mBlend));
HR(mFX->SetValue(mhTexOffset, &mTexOffset, sizeof(D3DXVECTOR2)));
HR(mFX->SetValue(mhBlendOffset, &mBlendOffset, sizeof(D3DXVECTOR2)));
HR(gd3dDevice->SetStreamSource(0, mBoxVB, 0, sizeof(VertexPNT)));
// Begin passes.
UINT numPasses = 0;
HR(mFX->Begin(&numPasses, 0));
for(UINT i = 0; i < numPasses; ++i)

HR(gd3dDevice->DrawIndexedPrimitive(D3DPT_TRIANGLELIST, 0, 0, 24, 0, 12));

// Present the backbuffer.
HR(gd3dDevice->Present(0, 0, 0, 0));
void FlareCubeDemo::buildBoxGeometry()
// Create the vertex buffer.
HR(gd3dDevice->CreateVertexBuffer(24 * sizeof(VertexPNT), D3DUSAGE_WRITEONLY,
0, D3DPOOL_MANAGED, &mBoxVB, 0));
// Write box vertices to the vertex buffer.
VertexPNT* v = 0;
HR(mBoxVB->Lock(0, 0, (void**)&v, 0));
// Fill in the front face vertex data.
v[0] = VertexPNT(-1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 1.0f);
v[1] = VertexPNT(-1.0f, 1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 0.0f, 0.0f);
v[2] = VertexPNT( 1.0f, 1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 0.0f);
v[3] = VertexPNT( 1.0f, -1.0f, -1.0f, 0.0f, 0.0f, -1.0f, 1.0f, 1.0f);
// Fill in the back face vertex data.
v[4] = VertexPNT(-1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 1.0f);
v[5] = VertexPNT( 1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 1.0f);
v[6] = VertexPNT( 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f);
v[7] = VertexPNT(-1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f);
// Fill in the top face vertex data.
v[8] = VertexPNT(-1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f);
v[9] = VertexPNT(-1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f);
v[10] = VertexPNT( 1.0f, 1.0f, 1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 0.0f);
v[11] = VertexPNT( 1.0f, 1.0f, -1.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f);
// Fill in the bottom face vertex data.
v[12] = VertexPNT(-1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 1.0f);
v[13] = VertexPNT( 1.0f, -1.0f, -1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 1.0f);
v[14] = VertexPNT( 1.0f, -1.0f, 1.0f, 0.0f, -1.0f, 0.0f, 0.0f, 0.0f);
v[15] = VertexPNT(-1.0f, -1.0f, 1.0f, 0.0f, -1.0f, 0.0f, 1.0f, 0.0f);
// Fill in the left face vertex data.
v[16] = VertexPNT(-1.0f, -1.0f, 1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 1.0f);
v[17] = VertexPNT(-1.0f, 1.0f, 1.0f, -1.0f, 0.0f, 0.0f, 0.0f, 0.0f);
v[18] = VertexPNT(-1.0f, 1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 0.0f);
v[19] = VertexPNT(-1.0f, -1.0f, -1.0f, -1.0f, 0.0f, 0.0f, 1.0f, 1.0f);
// Fill in the right face vertex data.
v[20] = VertexPNT( 1.0f, -1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 1.0f);
v[21] = VertexPNT( 1.0f, 1.0f, -1.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f);
v[22] = VertexPNT( 1.0f, 1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 0.0f);
v[23] = VertexPNT( 1.0f, -1.0f, 1.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f);

// Create the vertex buffer.
HR(gd3dDevice->CreateIndexBuffer(36 * sizeof(WORD), D3DUSAGE_WRITEONLY,
// Write box indices to the index buffer.
WORD* i = 0;
HR(mBoxIB->Lock(0, 0, (void**)&i, 0));
// Fill in the front face index data
i[0] = 0; i[1] = 1; i[2] = 2;
i[3] = 0; i[4] = 2; i[5] = 3;
// Fill in the back face index data
i[6] = 4; i[7] = 5; i[8] = 6;
i[9] = 4; i[10] = 6; i[11] = 7;
// Fill in the top face index data
i[12] = 8; i[13] = 9; i[14] = 10;
i[15] = 8; i[16] = 10; i[17] = 11;
// Fill in the bottom face index data
i[18] = 12; i[19] = 13; i[20] = 14;
i[21] = 12; i[22] = 14; i[23] = 15;
// Fill in the left face index data
i[24] = 16; i[25] = 17; i[26] = 18;
i[27] = 16; i[28] = 18; i[29] = 19;
// Fill in the right face index data
i[30] = 20; i[31] = 21; i[32] = 22;
i[33] = 20; i[34] = 22; i[35] = 23;

And finally, the effect file in its entirety...

// CHAPTER 11 11.13 EXERCISE 6
uniform extern float4x4 gWorld;
uniform extern float4x4 gWorldInvTrans;
uniform extern float4x4 gWVP;
uniform extern float4 gAmbientMtrl;
uniform extern float4 gAmbientLight;
uniform extern float4 gDiffuseMtrl;
uniform extern float4 gDiffuseLight;
uniform extern float4 gSpecularMtrl;
uniform extern float4 gSpecularLight;
uniform extern float gSpecularPower;
uniform extern float3 gLightVecW;
uniform extern float3 gEyePosW;
uniform extern texture gTex;
uniform extern texture gBlend;
uniform extern float2 gTexOffset;
uniform extern float2 gBlendOffset;
// Use Anisotropic filtering since when we are low to the ground, the
// ground plane is near a 90 degree angle with our view direction.
sampler Tex0S = sampler_state
Texture = <gTex>;
MinFilter = Anisotropic;
MagFilter = LINEAR;
MipFilter = LINEAR;
MaxAnisotropy = 8;
AddressU = WRAP;
AddressV = WRAP;
sampler BlendS = sampler_state
Texture = <gBlend>;
MinFilter = LINEAR;
MagFilter = LINEAR;
MipFilter = LINEAR;
AddressU = WRAP;
AddressV = WRAP;

struct OutputVS
float4 posH : POSITION0;
float4 diffuse : COLOR0;
float4 spec : COLOR1;
float2 tex0 : TEXCOORD0;
float2 tex1 : TEXCOORD1;

OutputVS MultiTexVS(float3 posL : POSITION0,
float3 normalL : NORMAL0,
float2 tex0: TEXCOORD0)
// Zero out our output.
OutputVS outVS = (OutputVS)0;

// Transform normal to world space.
float3 normalW = mul(float4(normalL, 0.0f), gWorldInvTrans).xyz;
normalW = normalize(normalW);

// Transform vertex position to world space.
float3 posW = mul(float4(posL, 1.0f), gWorld).xyz;

// Compute the color: Equation 10.3.

// Compute the vector from the vertex to the eye position.
float3 toEye = normalize(gEyePosW - posW);

// Compute the reflection vector.
float3 r = reflect(-gLightVecW, normalW);

// Determine how much (if any) specular light makes it into the eye.
float t = pow(max(dot(r, toEye), 0.0f), gSpecularPower);

// Determine the diffuse light intensity that strikes the vertex.
float s = max(dot(gLightVecW, normalW), 0.0f);

// Compute the ambient, diffuse and specular terms separatly.
float3 spec = t*(gSpecularMtrl*gSpecularLight).rgb;
float3 diffuse = s*(gDiffuseMtrl*gDiffuseLight).rgb;
float3 ambient = gAmbientMtrl*gAmbientLight;

// Sum all the terms together and copy over the diffuse alpha.
outVS.diffuse.rgb = ambient + diffuse;
outVS.diffuse.a = gDiffuseMtrl.a;
outVS.spec = float4(spec, 0.0f);

// Transform to homogeneous clip space.
outVS.posH = mul(float4(posL, 1.0f), gWVP);

outVS.tex0 = tex0 + gTexOffset;
outVS.tex1 = tex0 + gBlendOffset;

// Done--return the output.
return outVS;
float4 MultiTexPS(float4 diffuse : COLOR0,
float4 spec : COLOR1,
float2 tex0 : TEXCOORD0,
float2 tex1 : TEXCOORD1) : COLOR
// Layer maps are tiled
float3 c0 = tex2D(Tex0S, tex0).rgb;

// Blendmap is not tiled.
float3 B = tex2D(BlendS, tex1).rgb;

// Scale the colors by each layer by its corresponding weight
// stored in the blendmap.
c0 *= B;

// Sum the colors and modulate with the lighting color.
float3 final = (c0) * diffuse.rgb;

return float4(final + spec, diffuse.a);
technique MultiTexTech
pass P0
// Specify the vertex and pixel shader associated with this pass.
vertexShader = compile vs_2_0 TerrainMultiTexVS();
pixelShader = compile ps_2_0 TerrainMultiTexPS();

What am I doing wrong? Do I have to redesign the whole thing usings two sets of texture coordinates instead of using offsets?

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Note that it only "appeared" to me that the textures are going around in a circle about the plane of each face. It is possible that I am seeing it wrong and that it is doing something entirely different. That could explain why the screen shot looks the way it is. Either way though, it's still not what I wanted, and I must be doing something wrong.

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Won't somebody help me? Please note, this is [i]not[/i] homework. I am simply studying this on my own for fun.

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outVS.tex0 = tex0 + gTexOffset;
outVS.tex1 = tex0 + gBlendOffset;
You're not really rotating here, just translating. Use a proper transformation, something like:

outVS.tex0 = mul(float4(tex0, 0, 1), gTexTransform1).xy;
outVS.tex1 = mul(float4(tex0, 0, 1), gTexTransform2).xy;
... and provide the rotation matrices just like you do with gWVP.

Edit: Correction: added .xy to suppress truncation warning.

Edit2: No feedback... entering lurk-mode. Edited by unbird

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Thanks unbird. I did what you suggested and everything works as expected now.

P.S. I will try to make a point of giving feedback in the future.

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