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+/* $Id: s_aatriangle.c,v 1.1 2000/10/31 18:00:04 keithw Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version: 3.5
+ *
+ * Copyright (C) 1999-2000 Brian Paul All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
+ * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+
+/*
+ * Antialiased Triangle rasterizers
+ */
+
+
+#include "s_aatriangle.h"
+#include "s_span.h"
+
+
+/*
+ * Compute coefficients of a plane using the X,Y coords of the v0, v1, v2
+ * vertices and the given Z values.
+ */
+static INLINE void
+compute_plane(const GLfloat v0[], const GLfloat v1[], const GLfloat v2[],
+ GLfloat z0, GLfloat z1, GLfloat z2, GLfloat plane[4])
+{
+ const GLfloat px = v1[0] - v0[0];
+ const GLfloat py = v1[1] - v0[1];
+ const GLfloat pz = z1 - z0;
+
+ const GLfloat qx = v2[0] - v0[0];
+ const GLfloat qy = v2[1] - v0[1];
+ const GLfloat qz = z2 - z0;
+
+ const GLfloat a = py * qz - pz * qy;
+ const GLfloat b = pz * qx - px * qz;
+ const GLfloat c = px * qy - py * qx;
+ const GLfloat d = -(a * v0[0] + b * v0[1] + c * z0);
+
+ plane[0] = a;
+ plane[1] = b;
+ plane[2] = c;
+ plane[3] = d;
+}
+
+
+/*
+ * Compute coefficients of a plane with a constant Z value.
+ */
+static INLINE void
+constant_plane(GLfloat value, GLfloat plane[4])
+{
+ plane[0] = 0.0;
+ plane[1] = 0.0;
+ plane[2] = -1.0;
+ plane[3] = value;
+}
+
+#define CONSTANT_PLANE(VALUE, PLANE) \
+do { \
+ PLANE[0] = 0.0F; \
+ PLANE[1] = 0.0F; \
+ PLANE[2] = -1.0F; \
+ PLANE[3] = VALUE; \
+} while (0)
+
+
+
+/*
+ * Solve plane equation for Z at (X,Y).
+ */
+static INLINE GLfloat
+solve_plane(GLfloat x, GLfloat y, const GLfloat plane[4])
+{
+ GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2];
+ return z;
+}
+
+
+#define SOLVE_PLANE(X, Y, PLANE) \
+ ((PLANE[3] + PLANE[0] * (X) + PLANE[1] * (Y)) / -PLANE[2])
+
+
+/*
+ * Return 1 / solve_plane().
+ */
+static INLINE GLfloat
+solve_plane_recip(GLfloat x, GLfloat y, const GLfloat plane[4])
+{
+ GLfloat z = -plane[2] / (plane[3] + plane[0] * x + plane[1] * y);
+ return z;
+}
+
+
+
+/*
+ * Solve plane and return clamped GLchan value.
+ */
+static INLINE GLchan
+solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4])
+{
+ GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2] + 0.5F;
+ if (z < 0.0F)
+ return 0;
+ else if (z > CHAN_MAXF)
+ return CHAN_MAXF;
+ return (GLchan) (GLint) z;
+}
+
+
+
+/*
+ * Compute how much (area) of the given pixel is inside the triangle.
+ * Vertices MUST be specified in counter-clockwise order.
+ * Return: coverage in [0, 1].
+ */
+static GLfloat
+compute_coveragef(const GLfloat v0[3], const GLfloat v1[3],
+ const GLfloat v2[3], GLint winx, GLint winy)
+{
+ static const GLfloat samples[16][2] = {
+ /* start with the four corners */
+ { 0.00, 0.00 },
+ { 0.75, 0.00 },
+ { 0.00, 0.75 },
+ { 0.75, 0.75 },
+ /* continue with interior samples */
+ { 0.25, 0.00 },
+ { 0.50, 0.00 },
+ { 0.00, 0.25 },
+ { 0.25, 0.25 },
+ { 0.50, 0.25 },
+ { 0.75, 0.25 },
+ { 0.00, 0.50 },
+ { 0.25, 0.50 },
+ { 0.50, 0.50 },
+ { 0.75, 0.50 },
+ { 0.25, 0.75 },
+ { 0.50, 0.75 }
+ };
+ const GLfloat x = (GLfloat) winx;
+ const GLfloat y = (GLfloat) winy;
+ const GLfloat dx0 = v1[0] - v0[0];
+ const GLfloat dy0 = v1[1] - v0[1];
+ const GLfloat dx1 = v2[0] - v1[0];
+ const GLfloat dy1 = v2[1] - v1[1];
+ const GLfloat dx2 = v0[0] - v2[0];
+ const GLfloat dy2 = v0[1] - v2[1];
+ GLint stop = 4, i;
+ GLfloat insideCount = 16.0F;
+
+#ifdef DEBUG
+ {
+ const GLfloat area = dx0 * dy1 - dx1 * dy0;
+ assert(area >= 0.0);
+ }
+#endif
+
+ for (i = 0; i < stop; i++) {
+ const GLfloat sx = x + samples[i][0];
+ const GLfloat sy = y + samples[i][1];
+ const GLfloat fx0 = sx - v0[0];
+ const GLfloat fy0 = sy - v0[1];
+ const GLfloat fx1 = sx - v1[0];
+ const GLfloat fy1 = sy - v1[1];
+ const GLfloat fx2 = sx - v2[0];
+ const GLfloat fy2 = sy - v2[1];
+ /* cross product determines if sample is inside or outside each edge */
+ GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
+ GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
+ GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
+ /* Check if the sample is exactly on an edge. If so, let cross be a
+ * positive or negative value depending on the direction of the edge.
+ */
+ if (cross0 == 0.0F)
+ cross0 = dx0 + dy0;
+ if (cross1 == 0.0F)
+ cross1 = dx1 + dy1;
+ if (cross2 == 0.0F)
+ cross2 = dx2 + dy2;
+ if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
+ /* point is outside triangle */
+ insideCount -= 1.0F;
+ stop = 16;
+ }
+ }
+ if (stop == 4)
+ return 1.0F;
+ else
+ return insideCount * (1.0F / 16.0F);
+}
+
+
+
+/*
+ * Compute how much (area) of the given pixel is inside the triangle.
+ * Vertices MUST be specified in counter-clockwise order.
+ * Return: coverage in [0, 15].
+ */
+static GLint
+compute_coveragei(const GLfloat v0[3], const GLfloat v1[3],
+ const GLfloat v2[3], GLint winx, GLint winy)
+{
+ /* NOTE: 15 samples instead of 16.
+ * A better sample distribution could be used.
+ */
+ static const GLfloat samples[15][2] = {
+ /* start with the four corners */
+ { 0.00, 0.00 },
+ { 0.75, 0.00 },
+ { 0.00, 0.75 },
+ { 0.75, 0.75 },
+ /* continue with interior samples */
+ { 0.25, 0.00 },
+ { 0.50, 0.00 },
+ { 0.00, 0.25 },
+ { 0.25, 0.25 },
+ { 0.50, 0.25 },
+ { 0.75, 0.25 },
+ { 0.00, 0.50 },
+ { 0.25, 0.50 },
+ /*{ 0.50, 0.50 },*/
+ { 0.75, 0.50 },
+ { 0.25, 0.75 },
+ { 0.50, 0.75 }
+ };
+ const GLfloat x = (GLfloat) winx;
+ const GLfloat y = (GLfloat) winy;
+ const GLfloat dx0 = v1[0] - v0[0];
+ const GLfloat dy0 = v1[1] - v0[1];
+ const GLfloat dx1 = v2[0] - v1[0];
+ const GLfloat dy1 = v2[1] - v1[1];
+ const GLfloat dx2 = v0[0] - v2[0];
+ const GLfloat dy2 = v0[1] - v2[1];
+ GLint stop = 4, i;
+ GLint insideCount = 15;
+
+#ifdef DEBUG
+ {
+ const GLfloat area = dx0 * dy1 - dx1 * dy0;
+ assert(area >= 0.0);
+ }
+#endif
+
+ for (i = 0; i < stop; i++) {
+ const GLfloat sx = x + samples[i][0];
+ const GLfloat sy = y + samples[i][1];
+ const GLfloat fx0 = sx - v0[0];
+ const GLfloat fy0 = sy - v0[1];
+ const GLfloat fx1 = sx - v1[0];
+ const GLfloat fy1 = sy - v1[1];
+ const GLfloat fx2 = sx - v2[0];
+ const GLfloat fy2 = sy - v2[1];
+ /* cross product determines if sample is inside or outside each edge */
+ GLfloat cross0 = (dx0 * fy0 - dy0 * fx0);
+ GLfloat cross1 = (dx1 * fy1 - dy1 * fx1);
+ GLfloat cross2 = (dx2 * fy2 - dy2 * fx2);
+ /* Check if the sample is exactly on an edge. If so, let cross be a
+ * positive or negative value depending on the direction of the edge.
+ */
+ if (cross0 == 0.0F)
+ cross0 = dx0 + dy0;
+ if (cross1 == 0.0F)
+ cross1 = dx1 + dy1;
+ if (cross2 == 0.0F)
+ cross2 = dx2 + dy2;
+ if (cross0 < 0.0F || cross1 < 0.0F || cross2 < 0.0F) {
+ /* point is outside triangle */
+ insideCount--;
+ stop = 15;
+ }
+ }
+ if (stop == 4)
+ return 15;
+ else
+ return insideCount;
+}
+
+
+
+static void
+rgba_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_RGBA
+#include "s_aatritemp.h"
+}
+
+
+static void
+index_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_INDEX
+#include "s_aatritemp.h"
+}
+
+
+/*
+ * Compute mipmap level of detail.
+ */
+static INLINE GLfloat
+compute_lambda(const GLfloat sPlane[4], const GLfloat tPlane[4],
+ GLfloat invQ, GLfloat width, GLfloat height)
+{
+ GLfloat dudx = sPlane[0] / sPlane[2] * invQ * width;
+ GLfloat dudy = sPlane[1] / sPlane[2] * invQ * width;
+ GLfloat dvdx = tPlane[0] / tPlane[2] * invQ * height;
+ GLfloat dvdy = tPlane[1] / tPlane[2] * invQ * height;
+ GLfloat r1 = dudx * dudx + dudy * dudy;
+ GLfloat r2 = dvdx * dvdx + dvdy * dvdy;
+ GLfloat rho2 = r1 + r2;
+ /* return log base 2 of rho */
+ return log(rho2) * 1.442695 * 0.5; /* 1.442695 = 1/log(2) */
+}
+
+
+static void
+tex_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_RGBA
+#define DO_TEX
+#include "s_aatritemp.h"
+}
+
+
+static void
+spec_tex_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_RGBA
+#define DO_TEX
+#define DO_SPEC
+#include "s_aatritemp.h"
+}
+
+
+static void
+multitex_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_RGBA
+#define DO_MULTITEX
+#include "s_aatritemp.h"
+}
+
+static void
+spec_multitex_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
+{
+#define DO_Z
+#define DO_RGBA
+#define DO_MULTITEX
+#define DO_SPEC
+#include "s_aatritemp.h"
+}
+
+
+/*
+ * Examine GL state and set ctx->Driver.TriangleFunc to an
+ * appropriate antialiased triangle rasterizer function.
+ */
+void
+_mesa_set_aa_triangle_function(GLcontext *ctx)
+{
+ ASSERT(ctx->Polygon.SmoothFlag);
+ if (ctx->Texture.ReallyEnabled) {
+ if (ctx->Light.Enabled &&
+ ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR) {
+ if (ctx->Texture.MultiTextureEnabled) {
+ ctx->Driver.TriangleFunc = spec_multitex_aa_tri;
+ }
+ else {
+ ctx->Driver.TriangleFunc = spec_tex_aa_tri;
+ }
+ }
+ else {
+ if (ctx->Texture.MultiTextureEnabled) {
+ ctx->Driver.TriangleFunc = multitex_aa_tri;
+ }
+ else {
+ ctx->Driver.TriangleFunc = tex_aa_tri;
+ }
+ }
+ }
+ else {
+ if (ctx->Visual.RGBAflag) {
+ ctx->Driver.TriangleFunc = rgba_aa_tri;
+ }
+ else {
+ ctx->Driver.TriangleFunc = index_aa_tri;
+ }
+ }
+ ASSERT(ctx->Driver.TriangleFunc);
+}
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