Recursive reflection in OpenGL: Base on the recursive algorithm in unit 10 secti

Question

Recursive reflection in OpenGL:

Base on the recursive algorithm in unit 10 section 2 objective 3 (shown below), implement a recursive routine in the program of unit 11 section 2 objective 1 (shown below) to produce a similar reflective effect. The minimum requirement is to rewrite the method render() of the program to implement the recursive ray tracing algorithm. The implemented recursive method should cast a ray from the ray source to the scene. The ray may either hit the wall (a non-reflective surface here) or hit the floor (a reflective surface here). If it hits the wall, the method can terminate the recursion and return the local color of the wall. If the ray hits the floor, the method should (recursively) invoke itself with the reflection ray, and calculate and return the mixed color as demonstrated in the original render() routine. You may hard-code the inclusion test or you may implement your own method to support the inclusion. Also you may need to hard-code the normal vector of the wall and the floor. Feel free to change the program to suit your needs.

Recursive algorithm in unit 10 section 2 objective 3 (pseudocode):

Program of unit 11 section 2 objective 1 (uses basic ray tracing rather than a recursive ray tracing algorithm):

Explanation / Answer

// check mirror recursion count if (MirrorRecursion >= MAX_MIRROR_RECURSION) return DM_MIRROR_NO_ERROR; MirrorRecursion++; // create stencil mask glClear(GL_STENCIL_BUFFER_BIT); glEnable(GL_STENCIL_TEST); glStencilFunc(GL_ALWAYS, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glColorMask(0, 0, 0, 0); glBegin(GL_QUADS); glNormal3f(1.0f, 0.0f, 0.0f); glTexCoord2f(0.0f, 0.0f); glVertex3f(a.x, a.y, a.z); glVertex3f(b.x, b.y, b.z); glVertex3f(c.x, c.y, c.z); glVertex3f(d.x, d.y, d.z); glEnd(); // draw mirrored scene glColorMask(1, 1, 1, 1); glStencilFunc(GL_EQUAL, 1, 1); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); glEnable(GL_CLIP_PLANE0); glClipPlane(GL_CLIP_PLANE0, p); dmFlipFaces(); glPushMatrix(); glMultMatrixf(m); glClear(GL_DEPTH_BUFFER_BIT); Scene->Render(); glPopMatrix(); dmFlipFaces(); glDisable(GL_CLIP_PLANE0); glDisable(GL_STENCIL_TEST); MirrorRecursion--;

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