redesigned box clipping code in R_Shadow_ScissorForBBox, now clips edges

against the nearplane rather than doing brush building (too slow)

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@7812 d7cf8633-e32d-0410-b094-e92efae38249

diff --git a/r_shadow.c b/r_shadow.c
index c520ac5711273bb37046adbe048e31f2a4f1f73c..ebcb4601810e1c8867123ebc888a1847a543749e 100644 (file)
--- a/r_shadow.c
+++ b/r_shadow.c
@@ -1193,14 +1193,41 @@ void R_Shadow_RenderMode_End(void)
        r_shadow_rendermode = R_SHADOW_RENDERMODE_NONE;
 }
 
+int bboxedges[12][2] =
+{
+       // top
+       {0, 1}, // +X
+       {0, 2}, // +Y
+       {1, 3}, // Y, +X
+       {2, 3}, // X, +Y
+       // bottom
+       {4, 5}, // +X
+       {4, 6}, // +Y
+       {5, 7}, // Y, +X
+       {6, 7}, // X, +Y
+       // verticals
+       {0, 4}, // +Z
+       {1, 5}, // X, +Z
+       {2, 6}, // Y, +Z
+       {3, 7}, // XY, +Z
+};
+
 qboolean R_Shadow_ScissorForBBox(const float *mins, const float *maxs)
 {
        int i, ix1, iy1, ix2, iy2;
        float x1, y1, x2, y2;
        vec4_t v, v2;
-       rmesh_t mesh;
-       mplane_t planes[11];
-       float vertex3f[256*3];
+       float vertex[20][3];
+       int j, k;
+       vec4_t plane4f;
+       int numvertices;
+       float corner[8][4];
+       float dist[8];
+       int sign[8];
+       float f;
+
+       if (!r_shadow_scissor.integer)
+               return false;
 
        // if view is inside the light box, just say yes it's visible
        if (BoxesOverlap(r_view.origin, r_view.origin, mins, maxs))
@@ -1209,40 +1236,52 @@ qboolean R_Shadow_ScissorForBBox(const float *mins, const float *maxs)
                return false;
        }
 
-       // create a temporary brush describing the area the light can affect in worldspace
-       VectorNegate(r_view.frustum[0].normal, planes[ 0].normal);planes[ 0].dist = -r_view.frustum[0].dist;
-       VectorNegate(r_view.frustum[1].normal, planes[ 1].normal);planes[ 1].dist = -r_view.frustum[1].dist;
-       VectorNegate(r_view.frustum[2].normal, planes[ 2].normal);planes[ 2].dist = -r_view.frustum[2].dist;
-       VectorNegate(r_view.frustum[3].normal, planes[ 3].normal);planes[ 3].dist = -r_view.frustum[3].dist;
-       VectorNegate(r_view.frustum[4].normal, planes[ 4].normal);planes[ 4].dist = -r_view.frustum[4].dist;
-       VectorSet   (planes[ 5].normal,  1, 0, 0);         planes[ 5].dist =  maxs[0];
-       VectorSet   (planes[ 6].normal, -1, 0, 0);         planes[ 6].dist = -mins[0];
-       VectorSet   (planes[ 7].normal, 0,  1, 0);         planes[ 7].dist =  maxs[1];
-       VectorSet   (planes[ 8].normal, 0, -1, 0);         planes[ 8].dist = -mins[1];
-       VectorSet   (planes[ 9].normal, 0, 0,  1);         planes[ 9].dist =  maxs[2];
-       VectorSet   (planes[10].normal, 0, 0, -1);         planes[10].dist = -mins[2];
-
-       // turn the brush into a mesh
-       memset(&mesh, 0, sizeof(rmesh_t));
-       mesh.maxvertices = 256;
-       mesh.vertex3f = vertex3f;
-       mesh.epsilon2 = (1.0f / (32.0f * 32.0f));
-       R_Mesh_AddBrushMeshFromPlanes(&mesh, 11, planes);
-
-       // if that mesh is empty, the light is not visible at all
-       if (!mesh.numvertices)
-               return true;
+       x1 = y1 = x2 = y2 = 0;
 
-       if (!r_shadow_scissor.integer)
-               return false;
+       // transform all corners that are infront of the nearclip plane
+       VectorNegate(r_view.frustum[4].normal, plane4f);
+       plane4f[3] = r_view.frustum[4].dist;
+       numvertices = 0;
+       for (i = 0;i < 8;i++)
+       {
+               Vector4Set(corner[i], (i & 1) ? maxs[0] : mins[0], (i & 2) ? maxs[1] : mins[1], (i & 4) ? maxs[2] : mins[2], 1);
+               dist[i] = DotProduct4(corner[i], plane4f);
+               sign[i] = dist[i] > 0;
+               if (!sign[i])
+               {
+                       VectorCopy(corner[i], vertex[numvertices]);
+                       numvertices++;
+               }
+       }
+       // if some points are behind the nearclip, add clipped edge points to make
+       // sure that the scissor boundary is complete
+       if (numvertices > 0 && numvertices < 8)
+       {
+               // add clipped edge points
+               for (i = 0;i < 12;i++)
+               {
+                       j = bboxedges[i][0];
+                       k = bboxedges[i][1];
+                       if (sign[j] != sign[k])
+                       {
+                               f = dist[j] / (dist[j] - dist[k]);
+                               VectorLerp(corner[j], f, corner[k], vertex[numvertices]);
+                               numvertices++;
+                       }
+               }
+       }
+
+       // if we have no points to check, the light is behind the view plane
+       if (!numvertices)
+               return true;
 
-       // if that mesh is not empty, check what area of the screen it covers
+       // if we have some points to transform, check what screen area is covered
        x1 = y1 = x2 = y2 = 0;
        v[3] = 1.0f;
-       //Con_Printf("%i vertices to transform...\n", mesh.numvertices);
-       for (i = 0;i < mesh.numvertices;i++)
+       //Con_Printf("%i vertices to transform...\n", numvertices);
+       for (i = 0;i < numvertices;i++)
        {
-               VectorCopy(mesh.vertex3f + i * 3, v);
+               VectorCopy(vertex[i], v);
                GL_TransformToScreen(v, v2);
                //Con_Printf("%.3f %.3f %.3f %.3f transformed to %.3f %.3f %.3f %.3f\n", v[0], v[1], v[2], v[3], v2[0], v2[1], v2[2], v2[3]);
                if (i)