/*
 * Copyright © 2014 Keith Packard
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include "glamor_priv.h"
#include "glamor_program.h"
#include "glamor_transform.h"

static const glamor_facet glamor_facet_polyfillrect_130 = {
    .name = "poly_fill_rect",
    .version = 130,
    .vs_vars = "attribute vec4 primitive;\n",
    .vs_exec = ("       vec2 pos = primitive.zw * vec2(gl_VertexID&1, (gl_VertexID&2)>>1);\n"
                GLAMOR_POS(gl_Position, (primitive.xy + pos))),
};

static const glamor_facet glamor_facet_polyfillrect_120 = {
    .name = "poly_fill_rect",
    .vs_vars = "attribute vec2 primitive;\n",
    .vs_exec = ("        vec2 pos = vec2(0,0);\n"
                GLAMOR_POS(gl_Position, primitive.xy)),
};

static Bool
glamor_poly_fill_rect_gl(DrawablePtr drawable,
                         GCPtr gc, int nrect, xRectangle *prect)
{
    ScreenPtr screen = drawable->pScreen;
    glamor_screen_private *glamor_priv = glamor_get_screen_private(screen);
    PixmapPtr pixmap = glamor_get_drawable_pixmap(drawable);
    glamor_pixmap_private *pixmap_priv;
    glamor_program *prog;
    int off_x, off_y;
    GLshort *v;
    char *vbo_offset;
    int box_x, box_y;

    pixmap_priv = glamor_get_pixmap_private(pixmap);
    if (!GLAMOR_PIXMAP_PRIV_HAS_FBO(pixmap_priv))
        goto bail;

    glamor_make_current(glamor_priv);

    if (glamor_priv->glsl_version >= 130) {
        prog = glamor_use_program_fill(pixmap, gc,
                                       &glamor_priv->poly_fill_rect_program,
                                       &glamor_facet_polyfillrect_130);

        if (!prog)
            goto bail;

        /* Set up the vertex buffers for the points */

        v = glamor_get_vbo_space(drawable->pScreen, nrect * sizeof (xRectangle), &vbo_offset);

        glEnableVertexAttribArray(GLAMOR_VERTEX_POS);
        glVertexAttribDivisor(GLAMOR_VERTEX_POS, 1);
        glVertexAttribPointer(GLAMOR_VERTEX_POS, 4, GL_SHORT, GL_FALSE,
                              4 * sizeof (short), vbo_offset);

        memcpy(v, prect, nrect * sizeof (xRectangle));

        glamor_put_vbo_space(screen);
    } else {
        int n;

        prog = glamor_use_program_fill(pixmap, gc,
                                       &glamor_priv->poly_fill_rect_program,
                                       &glamor_facet_polyfillrect_120);

        if (!prog)
            goto bail;

        /* Set up the vertex buffers for the points */

        v = glamor_get_vbo_space(drawable->pScreen, nrect * 8 * sizeof (short), &vbo_offset);

        glEnableVertexAttribArray(GLAMOR_VERTEX_POS);
        glVertexAttribPointer(GLAMOR_VERTEX_POS, 2, GL_SHORT, GL_FALSE,
                              2 * sizeof (short), vbo_offset);

        for (n = 0; n < nrect; n++) {
            v[0] = prect->x;                v[1] = prect->y;
            v[2] = prect->x;                v[3] = prect->y + prect->height;
            v[4] = prect->x + prect->width; v[5] = prect->y + prect->height;
            v[6] = prect->x + prect->width; v[7] = prect->y;
            prect++;
            v += 8;
        }

        glamor_put_vbo_space(screen);
    }

    glEnable(GL_SCISSOR_TEST);

    glamor_pixmap_loop(pixmap_priv, box_x, box_y) {
        int nbox = RegionNumRects(gc->pCompositeClip);
        BoxPtr box = RegionRects(gc->pCompositeClip);

        glamor_set_destination_drawable(drawable, box_x, box_y, TRUE, FALSE, prog->matrix_uniform, &off_x, &off_y);

        while (nbox--) {
            glScissor(box->x1 + off_x,
                      box->y1 + off_y,
                      box->x2 - box->x1,
                      box->y2 - box->y1);
            box++;
            if (glamor_priv->glsl_version >= 130)
                glDrawArraysInstanced(GL_TRIANGLE_STRIP, 0, 4, nrect);
            else {
                if (glamor_priv->gl_flavor == GLAMOR_GL_DESKTOP) {
                    glDrawArrays(GL_QUADS, 0, nrect * 4);
                } else {
                    int i;
                    for (i = 0; i < nrect; i++) {
                        glDrawArrays(GL_TRIANGLE_FAN, i * 4, 4);
                    }
                }
            }
        }
    }

    glDisable(GL_SCISSOR_TEST);
    if (glamor_priv->glsl_version >= 130)
        glVertexAttribDivisor(GLAMOR_VERTEX_POS, 0);
    glDisableVertexAttribArray(GLAMOR_VERTEX_POS);

    return TRUE;
bail:
    return FALSE;
}

static void
glamor_poly_fill_rect_bail(DrawablePtr drawable,
                           GCPtr gc, int nrect, xRectangle *prect)
{
    glamor_fallback("to %p (%c)\n", drawable,
                    glamor_get_drawable_location(drawable));
    if (glamor_prepare_access(drawable, GLAMOR_ACCESS_RW) &&
        glamor_prepare_access_gc(gc)) {
        fbPolyFillRect(drawable, gc, nrect, prect);
    }
    glamor_finish_access_gc(gc);
    glamor_finish_access(drawable);
}

void
glamor_poly_fill_rect(DrawablePtr drawable,
                      GCPtr gc, int nrect, xRectangle *prect)
{
    if (glamor_poly_fill_rect_gl(drawable, gc, nrect, prect))
        return;
    glamor_poly_fill_rect_bail(drawable, gc, nrect, prect);
}