Jump to content
• Advertisement # poefie

Member

7

141 Neutral

## About poefie

• Rank
Newbie
1. ## Is my texture mapper correct?

OK I've updated the original post.
2. I've been working on subpixel accuracy for my point sampler and at this point I'm not sure if it can get any better without anti-aliasing and filtering.  I can see some texel wobbling around the edges of the capsule model where the texture is really stretched. So my question is, is this a bug or merely as good as it gets?   If I run Chris Hecker's rasterizing code it seems to do the same thing.
3. Hmm, if a merger of our enterprises could be a strategic fit we might fast track a proactive result driven game plan with win-win synergy and out-of-the-box thinking. Hardball!   I'd rather profile than optimize, and to do that I need a fully working engine with all the bells and whistles first.
4. ## Is Programming Fun or Work for you?

I hate it I hate it I hate it I hate it!!!!!!!!! But I like what you can do with it. If only it would work the first time...
5. Thanks for the tips fir, I will look into it when I get there again.   I finally fixed it! The missing triangles were fixed by using slope size instead of vertex position to determine the direction of a line scan. if(slope1>slope2) instead of if(x1>x2) .   The gaps were fixed by using height= floor(y2)-floor(y1) instead of height=floor(y2-y1). Because |a-b| <= |a|-|b| so |10-5.9|=4 but |10|-|5.9|=5.
6. floatToInt is for faster integer conversion than casting. I replaced it with floor for your readability.   I do 1/z too:   zInv1 = 1 / it.vert1.z; it.vert1.x = ( viewDistance *  it.vert1.x ) * zInv1; it.vert1.y = ( viewDistance * -it.vert1.y ) * (aspectRatio * zInv1);   I don't have fast code sorry.
7. I don't know whats wrong here, I have two bits of code that do the same thing but only one works and I can't see why. The first listing draws the blue helicopter. The problem is there are gaps between the triangles. Also some triangles are missing. Maybe its a fencepost error related to pre-increment in a loop. Maybe Incorrect accumulation of fractional parts. Maybe Incorrect cutoff of fractional parts.   Wheres wally? __forceinline int * floatToInt(int *int_pointer, float f) { *int_pointer = floor(f); return int_pointer; } //textureTriangle2D members are all floats void Rasterizer::textureTriangle(textureTriangle2D & tri) { real temp; // real is a float int slopeLeft; int slopeRight; //sort top to bottom //y is 0 at top of screen if (tri.y1 > tri.y3) { SWAP(tri.y1, tri.y3, temp); SWAP(tri.x1, tri.x3, temp); } if (tri.y1 > tri.y2) { SWAP(tri.y1, tri.y2, temp); SWAP(tri.x1, tri.x2, temp); } if (tri.y2 > tri.y3) { SWAP(tri.y2, tri.y3, temp); SWAP(tri.x2, tri.x3, temp); } //height of top and bottom half of triangle real topHeight = tri.y2 - tri.y1; real bottomHeight = tri.y3 - tri.y2; floatToInt(&slopeRight, ((tri.x2 - tri.x1) * 65536) / topHeight); floatToInt(&slopeLeft, ((tri.x3 - tri.x1) * 65536) / (topHeight + bottomHeight)); int x1, x2, y1; floatToInt(&x1, tri.x1 * 65536); x2 = x1; floatToInt(&y1, tri.y1); int currentLocation; currentLocation = (pitch * y1); //flat bottom int h = floor(topHeight); if (h > 0) { if (tri.x2 > tri.x1) flatBottomTriangle(x1, slopeLeft, x2, slopeRight, h, currentLocation); else flatBottomTriangle(x2, slopeRight, x1, slopeLeft, h, currentLocation); } int offset; floatToInt(&offset, slopeLeft * floor(topHeight)); x1 = x1 + offset; floatToInt(&x2, tri.x2 * 65536); currentLocation += pitch *floor(topHeight); floatToInt(&slopeRight, ((tri.x3 - tri.x2) * 65536) / (bottomHeight)); int h = floor(bottomHeight); if (h > 0) { if (tri.x2 > tri.x1) flatBottomTriangle(x1, slopeLeft, x2, slopeRight, h, currentLocation); else flatBottomTriangle(x2, slopeRight, x1, slopeLeft, h, currentLocation); } } __forceinline void flatBottomTriangle(int x1, int slopeLeft, int x2, int slopeRight, real height, int currentLocation) { do { x1 += slopeLeft; x2 += slopeRight; int index = currentLocation + (x1 >> 16); while ( index ++ < currentLocation+(x2 >> 16) ) { //show overlapping pixels in red if (screenBuffer[index ] == 0) screenBuffer[index ] = 255; else screenBuffer[index ] = 255 << 16; } currentLocation += pitch; } while( --height > 0 ); } For what its worth I also have the following code which does the same thing and works. I can't see the difference. It draws they grey helicopter. __forceinline int * floatToInt(int *int_pointer, float f) { *int_pointer = floor(f); /*__asm fld f; __asm mov edx,int_pointer; __asm FRNDINT; __asm fistp dword ptr [edx];*/ return int_pointer; } //all textureTriangle2D members are floats void Rasterizer::flatTriangle( flatTriangle2D & tri ) { real temp; int clip; bool topDone = false; if ( tri.y1 > tri.y3 ) { SWAP( tri.x1, tri.x3, temp ); SWAP( tri.y1, tri.y3, temp ); } if ( tri.y1 > tri.y2 ) { SWAP( tri.y1, tri.y2, temp ); SWAP( tri.x1, tri.x2, temp ); } if ( tri.y2 > tri.y3 ) { SWAP( tri.x2, tri.x3, temp ); SWAP( tri.y2, tri.y3, temp ); } real x2x1 = tri.x2 - tri.x1; real x3x1 = tri.x3 - tri.x1; real x3x2 = tri.x3 - tri.x2; real y3y1 = tri.y3 - tri.y1; real y3y2 = tri.y3 - tri.y2; real y2y1 = tri.y2 - tri.y1; int x1; int x2; int y1; int y2; int y3; int tmp1 = 0; int tmp2 = 0; floatToInt( &y1, tri.y1 ); floatToInt( &y2, tri.y2 ); floatToInt( &y3, tri.y3 ); int shortSlope; int longSlope; floatToInt( &longSlope, ( x3x1 * 65536 ) / y3y1 ); //flat bottom if ( y1 != y2 ) { topDone = true; floatToInt( &x1, tri.x1 * 65536 ); floatToInt( &shortSlope, ( x2x1 * 65536 ) / y2y1 ); x2 = x1; for (; y1 < y2; y1++) { if ( x2 > x1 ) { tmp1 = x1 >> 16; tmp2 = x2 >> 16; if ( tmp1 < clipRect.left ) tmp1 = clipRect.left; if ( tmp2 > clipRect.right ) tmp2 = clipRect.right; if ( tmp1 < clipRect.right && tmp2 > clipRect.left) hLine( tmp1, tmp2, y1, tri.colour ); } else // from x2 to x1 { tmp1 = x2 >> 16; tmp2 = x1 >> 16; if ( tmp1 < clipRect.left) tmp1 = clipRect.left; if ( tmp2 > clipRect.right ) tmp2 = clipRect.right; if ( ( tmp1 < clipRect.right ) && ( tmp2 > clipRect.left ) ) hLine( tmp1, tmp2, y1, tri.colour ); } x1 += shortSlope; x2 += longSlope; } } //flat top if ( y2 != y3 ) { floatToInt( &x1, tri.x2 * 65536 ); if ( ! topDone ) { floatToInt( &x2, tri.x1 * 65536 ); } floatToInt( &shortSlope, ( x3x2 * 65536 ) / y3y2 ); for (; y2 < y3; y2++) { if ( x2 >= x1 ) { tmp1 = x1 >> 16; tmp2 = x2 >> 16; if ( tmp1 < clipRect.left ) tmp1 = clipRect.left; if ( tmp2 > clipRect.right ) tmp2 = clipRect.right; if ( tmp1 < clipRect.right && tmp2 > clipRect.left) hLine( tmp1, tmp2, y2, tri.colour ); } else // x2 starts x1 ends { tmp1 = x2 >> 16; tmp2 = x1 >> 16; if ( tmp1 < clipRect.left) tmp1 = clipRect.left; if ( tmp2 > clipRect.right ) tmp2 = clipRect.right; if ( ( tmp1 < clipRect.right ) && ( tmp2 > clipRect.left ) ) hLine( tmp1, tmp2, y2, tri.colour ); } x1 += shortSlope; x2 += longSlope; } } } inline void Rasterizer::hLine(int x, int x1, int y, COLOUR_DEPTH colour) { y *= pitch; while (x < x1) { screenBuffer[ y + x++ ] = colour; } }
• Advertisement
×

## Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!