63 lines
2.4 KiB
Java
63 lines
2.4 KiB
Java
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import algebra.*;
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import java.lang.Math.*;
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/**
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* The PerspectiveCorrectRasterizer class extends Rasterizer to perform Persepctive Correct interpolation
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* of attributes.
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*
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* @author cdehais
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*/
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public class PerspectiveCorrectRasterizer extends Rasterizer {
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public PerspectiveCorrectRasterizer (Shader shader) {
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super(shader);
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}
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/**
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* Rasterizes the triangular face made of the Fragment v1, v2 and v3
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*/
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public void rasterizeFace (Fragment v1, Fragment v2, Fragment v3) {
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Matrix C = makeBarycentricCoordsMatrix (v1, v2, v3);
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/* iterate over the triangle's bounding box */
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int xmin = Math.min (v1.getX (), Math.min (v2.getX (), v3.getX ()));
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int ymin = Math.min (v1.getY (), Math.min (v2.getY (), v3.getY ()));
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int xmax = Math.max (v1.getX (), Math.max (v2.getX (), v3.getX ()));
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int ymax = Math.max (v1.getY (), Math.max (v2.getY (), v3.getY ()));
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Fragment fragment = new Fragment (0, 0);
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int numAttributes = fragment.getNumAttributes ();
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try {
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for (int x = xmin; x <= xmax; x++) {
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for (int y = ymin; y <= ymax; y++) {
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/* setup position now to allow early clipping */
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fragment.setPosition (x, y);
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if (!shader.isClipped (fragment)) {
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Vector3 v = new Vector3 (1.0, (double)x, (double)y);
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Vector bar = C.multiply (v);
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if ((bar.get (0) >= 0.0) && (bar.get (1) >= 0.0) && (bar.get (2) >= 0.0)) {
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double oneOverZ = bar.get (0) / v1.getDepth () +
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bar.get (1) / v2.getDepth () +
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bar.get (2) / v3.getDepth ();
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for (int i = 0; i < numAttributes; i++) {
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double aOverZ = bar.get (0) * v1.getAttribute (i) / v1.getDepth () +
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bar.get (1) * v2.getAttribute (i) / v2.getDepth () +
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bar.get (2) * v3.getAttribute (i) / v3.getDepth ();
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fragment.setAttribute (i, aOverZ / oneOverZ);
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}
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shader.shade (fragment);
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}
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}
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}
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}
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} catch (SizeMismatchException e) {
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/* should not reach */
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e.printStackTrace ();
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}
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}
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}
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