/* $XFree86: xc/extras/Mesa/src/aatriangle.c,v 1.3 2001/12/11 09:18:54 alanh Exp $ */
/*
* Mesa 3-D graphics library
* Version: 3.3
*
* 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
*/
#ifdef PC_HEADER
#include "all.h"
#else
#include "glheader.h"
#include "aatriangle.h"
#include "span.h"
#include "types.h"
#include "vb.h"
#include "mmath.h"
#endif
/*
* 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 GLubyte value.
*/
static INLINE GLubyte
solve_plane_0_255(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 > 255.0F)
return 255;
return (GLubyte) (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)
{
#define B 0.125
static const GLfloat samples[16][2] = {
/* start with the four corners */
{ 0.00+B, 0.00+B },
{ 0.75+B, 0.00+B },
{ 0.00+B, 0.75+B },
{ 0.75+B, 0.75+B },
/* continue with interior samples */
{ 0.25+B, 0.00+B },
{ 0.50+B, 0.00+B },
{ 0.00+B, 0.25+B },
{ 0.25+B, 0.25+B },
{ 0.50+B, 0.25+B },
{ 0.75+B, 0.25+B },
{ 0.00+B, 0.50+B },
{ 0.25+B, 0.50+B },
{ 0.50+B, 0.50+B },
{ 0.75+B, 0.50+B },
{ 0.25+B, 0.75+B },
{ 0.50+B, 0.75+B }
};
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+B, 0.00+B },
{ 0.75+B, 0.00+B },
{ 0.00+B, 0.75+B },
{ 0.75+B, 0.75+B },
/* continue with interior samples */
{ 0.25+B, 0.00+B },
{ 0.50+B, 0.00+B },
{ 0.00+B, 0.25+B },
{ 0.25+B, 0.25+B },
{ 0.50+B, 0.25+B },
{ 0.75+B, 0.25+B },
{ 0.00+B, 0.50+B },
{ 0.25+B, 0.50+B },
/*{ 0.50, 0.50 },*/
{ 0.75+B, 0.50+B },
{ 0.25+B, 0.75+B },
{ 0.50+B, 0.75+B }
};
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 "aatritemp.h"
}
static void
index_aa_tri(GLcontext *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint pv)
{
#define DO_Z
#define DO_INDEX
#include "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_STUV0
#include "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_STUV0
#define DO_SPEC
#include "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_STUV0
#define DO_STUV1
#include "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_STUV0
#define DO_STUV1
#define DO_SPEC
#include "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.ReallyEnabled >= TEXTURE1_1D) {
ctx->Driver.TriangleFunc = spec_multitex_aa_tri;
}
else {
ctx->Driver.TriangleFunc = spec_tex_aa_tri;
}
}
else {
if (ctx->Texture.ReallyEnabled >= TEXTURE1_1D) {
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);
}