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GU Texture Problem

 
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Insert_witty_name



Joined: 10 May 2006
Posts: 376
PostPosted: Tue Sep 19, 2006 9:18 am    Post subject: GU Texture Problem Reply with quote
Hey.

I'm having issue with using GU to correctly display a texture.

I'm using an Ortho projection.

This is my drawing code:

Code:
void IMG_Draw(float sx, float sy, float width, float height, Image* image, float dx, float dy)
{
 if (!isDrawingStarted)
        return;
 
 sceKernelDcacheWritebackInvalidateAll();
 
 sceGumLoadIdentity();
 ScePspFVector3 pos = {dx + (width/2), dy + (height/2), 0};
 sceGumTranslate(&pos);
 
 if(image->rotation > 0.0f)
                    sceGumRotateZ(image->rotation);
 
 if(image->isSwizzled == 1)
        sceGuTexMode(GU_PSM_8888, 0, 0, GU_TRUE);
 
 sceGuTexImage(0, image->textureWidth, image->textureHeight, image->textureWidth, (void*) image->data);
 float u = 1.0f / ((float)image->textureWidth);
 float v = 1.0f / ((float)image->textureHeight);
 sceGuTexScale(u, v);
 
 float j = 0.0f;
   while (j < width) {
      VertexUV* vertices = (VertexUV*) sceGuGetMemory(4 * sizeof(VertexUV));
      float sliceWidth = 32.0f;
      if (j + sliceWidth > width) sliceWidth = width - j;
 
                vertices[0].u = sx + j;
                vertices[0].v = sy;
                vertices[0].x = (0 - (width/2)) + j;
                vertices[0].y = 0 - (height/2);
                vertices[0].z = 0;
                vertices[1].u = sx + sliceWidth + j;
                vertices[1].v = sy;
                vertices[1].x = (0 - (width/2)) + j + sliceWidth;
                vertices[1].y = 0 - (height/2);
                vertices[1].z = 0;
                vertices[2].u = sx + sliceWidth + j;
                vertices[2].v = sy + height;
                vertices[2].x = (0 - (width/2)) + j + sliceWidth;
                vertices[2].y = 0 + (height/2);
                vertices[2].z = 0;
                vertices[3].u = sx + j;
                vertices[3].v = sy + height;
                vertices[3].x = (0 - (width/2)) + j;
                vertices[3].y = 0 + (height/2);
                vertices[3].z = 0;
 
      sceGumDrawArray(GU_TRIANGLE_FAN, GU_TEXTURE_32BITF|GU_VERTEX_32BITF|GU_TRANSFORM_3D, 1*4, 0, vertices);
      j += sliceWidth;
   }

        sceGuTexMode(GU_PSM_8888, 0, 0, 0);
}


The problem is that I seem to get two horizontal lines across the screen (regardless of the image used).

Ilustrated in this screenshot:

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Insert_witty_name



Joined: 10 May 2006
Posts: 376
PostPosted: Tue Sep 26, 2006 6:17 pm    Post subject: Reply with quote
I'm still having problems with this if anyone has anything to suggest.

After extensive testing with Raphael it came to light that I need to change this line:

Code:
vertices[3].v = sy + height;


To this to correctly display a 512x512 texture:

Code:
vertices[3].v = sy + height + 2;


However this is not universal as it seems to change dependant upon the size of the texture. I'm not sure why this extra addition is needed as it should work without it.

I've tried stripping the function down to the bare minimum and used GU_SPRITES, not scaled the texture and given absolute U/V co-ordinates and still have the same issue.

Note that I'm using:

Code:
sceGuTexFilter(GU_NEAREST,GU_NEAREST);


If I change this to the following then I get no corruption - but the quality leaves very much to be desired:

Code:
sceGuTexFilter(GU_LINEAR,GU_LINEAR);


If anybody has any ideas I'd be happy to hear them.

Thanks.
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