+void GL_SetMirrorState(qboolean state);
+
+void R_Viewport_TransformToScreen(const r_viewport_t *v, const vec4_t in, vec4_t out)
+{
+ vec4_t temp;
+ float iw;
+ Matrix4x4_Transform4 (&v->viewmatrix, in, temp);
+ Matrix4x4_Transform4 (&v->projectmatrix, temp, out);
+ iw = 1.0f / out[3];
+ out[0] = v->x + (out[0] * iw + 1.0f) * v->width * 0.5f;
+ out[1] = v->y + v->height - (out[1] * iw + 1.0f) * v->height * 0.5f;
+ out[2] = v->z + (out[2] * iw + 1.0f) * v->depth * 0.5f;
+}
+
+static void R_Viewport_ApplyNearClipPlane(r_viewport_t *v, double normalx, double normaly, double normalz, double dist)
+{
+ double q[4];
+ double d;
+ float clipPlane[4], v3[3], v4[3];
+ float normal[3];
+
+ // This is inspired by Oblique Depth Projection from http://www.terathon.com/code/oblique.php
+
+ VectorSet(normal, normalx, normaly, normalz);
+ Matrix4x4_Transform3x3(&v->viewmatrix, normal, clipPlane);
+ VectorScale(normal, dist, v3);
+ Matrix4x4_Transform(&v->viewmatrix, v3, v4);
+ // FIXME: LordHavoc: I think this can be done more efficiently somehow but I can't remember the technique
+ clipPlane[3] = -DotProduct(v4, clipPlane);
+
+#if 0
+{
+ // testing code for comparing results
+ float clipPlane2[4];
+ VectorCopy4(clipPlane, clipPlane2);
+ R_Mesh_Matrix(&identitymatrix);
+ VectorSet(q, normal[0], normal[1], normal[2], -dist);
+ qglClipPlane(GL_CLIP_PLANE0, q);
+ qglGetClipPlane(GL_CLIP_PLANE0, q);
+ VectorCopy4(q, clipPlane);
+}
+#endif
+
+ // Calculate the clip-space corner point opposite the clipping plane
+ // as (sgn(clipPlane.x), sgn(clipPlane.y), 1, 1) and
+ // transform it into camera space by multiplying it
+ // by the inverse of the projection matrix
+ q[0] = ((clipPlane[0] < 0.0f ? -1.0f : clipPlane[0] > 0.0f ? 1.0f : 0.0f) + v->m[8]) / v->m[0];
+ q[1] = ((clipPlane[1] < 0.0f ? -1.0f : clipPlane[1] > 0.0f ? 1.0f : 0.0f) + v->m[9]) / v->m[5];
+ q[2] = -1.0f;
+ q[3] = (1.0f + v->m[10]) / v->m[14];
+
+ // Calculate the scaled plane vector
+ d = 2.0f / DotProduct4(clipPlane, q);
+
+ // Replace the third row of the projection matrix
+ v->m[2] = clipPlane[0] * d;
+ v->m[6] = clipPlane[1] * d;
+ v->m[10] = clipPlane[2] * d + 1.0f;
+ v->m[14] = clipPlane[3] * d;
+}
+
+void R_Viewport_InitOrtho(r_viewport_t *v, const matrix4x4_t *cameramatrix, int x, int y, int width, int height, double x1, double y1, double x2, double y2, double nearclip, double farclip, const double *nearplane)