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Diffstat (limited to 'mesalib/src/mesa/swrast/s_aatriangle.c')
| -rw-r--r-- | mesalib/src/mesa/swrast/s_aatriangle.c | 417 |
1 files changed, 417 insertions, 0 deletions
diff --git a/mesalib/src/mesa/swrast/s_aatriangle.c b/mesalib/src/mesa/swrast/s_aatriangle.c new file mode 100644 index 000000000..078f16aea --- /dev/null +++ b/mesalib/src/mesa/swrast/s_aatriangle.c @@ -0,0 +1,417 @@ +/* + * Mesa 3-D graphics library + * Version: 6.5.3 + * + * Copyright (C) 1999-2007 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 "main/glheader.h" +#include "main/context.h" +#include "main/colormac.h" +#include "main/context.h" +#include "main/macros.h" +#include "main/imports.h" +#include "s_aatriangle.h" +#include "s_context.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. + * A point (x,y,z) lies on plane iff a*x+b*y+c*z+d = 0. + */ +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; + + /* Crossproduct "(a,b,c):= dv1 x dv2" is orthogonal to plane. */ + const GLfloat a = py * qz - pz * qy; + const GLfloat b = pz * qx - px * qz; + const GLfloat c = px * qy - py * qx; + /* Point on the plane = "r*(a,b,c) + w", with fixed "r" depending + on the distance of plane from origin and arbitrary "w" parallel + to the plane. */ + /* The scalar product "(r*(a,b,c)+w)*(a,b,c)" is "r*(a^2+b^2+c^2)", + which is equal to "-d" below. */ + 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]) +{ + ASSERT(plane[2] != 0.0F); + return (plane[3] + plane[0] * x + plane[1] * y) / -plane[2]; +} + + +#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]) +{ + const GLfloat denom = plane[3] + plane[0] * x + plane[1] * y; + if (denom == 0.0F) + return 0.0F; + else + return -plane[2] / denom; +} + + +/* + * Solve plane and return clamped GLchan value. + */ +static INLINE GLchan +solve_plane_chan(GLfloat x, GLfloat y, const GLfloat plane[4]) +{ + const GLfloat z = (plane[3] + plane[0] * x + plane[1] * y) / -plane[2]; +#if CHAN_TYPE == GL_FLOAT + return CLAMP(z, 0.0F, CHAN_MAXF); +#else + if (z < 0) + return 0; + else if (z > CHAN_MAX) + return CHAN_MAX; + return (GLchan) IROUND_POS(z); +#endif +} + + +static INLINE GLfloat +plane_dx(const GLfloat plane[4]) +{ + return -plane[0] / plane[2]; +} + +static INLINE GLfloat +plane_dy(const GLfloat plane[4]) +{ + return -plane[1] / plane[2]; +} + + + +/* + * 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) +{ + /* Given a position [0,3]x[0,3] return the sub-pixel sample position. + * Contributed by Ray Tice. + * + * Jitter sample positions - + * - average should be .5 in x & y for each column + * - each of the 16 rows and columns should be used once + * - the rectangle formed by the first four points + * should contain the other points + * - the distrubition should be fairly even in any given direction + * + * The pattern drawn below isn't optimal, but it's better than a regular + * grid. In the drawing, the center of each subpixel is surrounded by + * four dots. The "x" marks the jittered position relative to the + * subpixel center. + */ +#define POS(a, b) (0.5+a*4+b)/16 + static const GLfloat samples[16][2] = { + /* start with the four corners */ + { POS(0, 2), POS(0, 0) }, + { POS(3, 3), POS(0, 2) }, + { POS(0, 0), POS(3, 1) }, + { POS(3, 1), POS(3, 3) }, + /* continue with interior samples */ + { POS(1, 1), POS(0, 1) }, + { POS(2, 0), POS(0, 3) }, + { POS(0, 3), POS(1, 3) }, + { POS(1, 2), POS(1, 0) }, + { POS(2, 3), POS(1, 2) }, + { POS(3, 2), POS(1, 1) }, + { POS(0, 1), POS(2, 2) }, + { POS(1, 0), POS(2, 1) }, + { POS(2, 1), POS(2, 3) }, + { POS(3, 0), POS(2, 0) }, + { POS(1, 3), POS(3, 0) }, + { POS(2, 2), POS(3, 2) } + }; + + 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]; + /* cross product determines if sample is inside or outside each edge */ + GLfloat cross = (dx0 * (sy - v0[1]) - dy0 * (sx - v0[0])); + /* 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 (cross == 0.0F) + cross = dx0 + dy0; + if (cross < 0.0F) { + /* sample point is outside first edge */ + insideCount -= 1.0F; + stop = 16; + } + else { + /* sample point is inside first edge */ + cross = (dx1 * (sy - v1[1]) - dy1 * (sx - v1[0])); + if (cross == 0.0F) + cross = dx1 + dy1; + if (cross < 0.0F) { + /* sample point is outside second edge */ + insideCount -= 1.0F; + stop = 16; + } + else { + /* sample point is inside first and second edges */ + cross = (dx2 * (sy - v2[1]) - dy2 * (sx - v2[0])); + if (cross == 0.0F) + cross = dx2 + dy2; + if (cross < 0.0F) { + /* sample point is outside third edge */ + 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. */ + static const GLfloat samples[15][2] = { + /* start with the four corners */ + { POS(0, 2), POS(0, 0) }, + { POS(3, 3), POS(0, 2) }, + { POS(0, 0), POS(3, 1) }, + { POS(3, 1), POS(3, 3) }, + /* continue with interior samples */ + { POS(1, 1), POS(0, 1) }, + { POS(2, 0), POS(0, 3) }, + { POS(0, 3), POS(1, 3) }, + { POS(1, 2), POS(1, 0) }, + { POS(2, 3), POS(1, 2) }, + { POS(3, 2), POS(1, 1) }, + { POS(0, 1), POS(2, 2) }, + { POS(1, 0), POS(2, 1) }, + { POS(2, 1), POS(2, 3) }, + { POS(3, 0), POS(2, 0) }, + { POS(1, 3), POS(3, 0) } + }; + 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, + const SWvertex *v0, + const SWvertex *v1, + const SWvertex *v2) +{ +#define DO_Z +#define DO_RGBA +#include "s_aatritemp.h" +} + + +static void +index_aa_tri(GLcontext *ctx, + const SWvertex *v0, + const SWvertex *v1, + const SWvertex *v2) +{ +#define DO_Z +#define DO_ATTRIBS +#define DO_INDEX +#include "s_aatritemp.h" +} + + +static void +general_aa_tri(GLcontext *ctx, + const SWvertex *v0, + const SWvertex *v1, + const SWvertex *v2) +{ +#define DO_Z +#define DO_RGBA +#define DO_ATTRIBS +#include "s_aatritemp.h" +} + + + +/* + * Examine GL state and set swrast->Triangle to an + * appropriate antialiased triangle rasterizer function. + */ +void +_swrast_set_aa_triangle_function(GLcontext *ctx) +{ + SWcontext *swrast = SWRAST_CONTEXT(ctx); + + ASSERT(ctx->Polygon.SmoothFlag); + + if (ctx->Texture._EnabledCoordUnits != 0 + || ctx->FragmentProgram._Current + || swrast->_FogEnabled + || NEED_SECONDARY_COLOR(ctx)) { + SWRAST_CONTEXT(ctx)->Triangle = general_aa_tri; + } + else if (ctx->Visual.rgbMode) { + SWRAST_CONTEXT(ctx)->Triangle = rgba_aa_tri; + } + else { + SWRAST_CONTEXT(ctx)->Triangle = index_aa_tri; + } + + ASSERT(SWRAST_CONTEXT(ctx)->Triangle); +} |