path: root/src/cairo-glsl.c

/* cairo - a vector graphics library with display and print output
 *
 * Copyright © 2008,2009 Intel Corporation
 *
 * This library is free software; you can redistribute it and/or
 * modify it either under the terms of the GNU Lesser General Public
 * License version 2.1 as published by the Free Software Foundation
 * (the "LGPL") or, at your option, under the terms of the Mozilla
 * Public License Version 1.1 (the "MPL"). If you do not alter this
 * notice, a recipient may use your version of this file under either
 * the MPL or the LGPL.
 *
 * You should have received a copy of the LGPL along with this library
 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 * You should have received a copy of the MPL along with this library
 * in the file COPYING-MPL-1.1
 *
 * The contents of this file are subject to the Mozilla Public License
 * Version 1.1 (the "License"); you may not use this file except in
 * compliance with the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
 * the specific language governing rights and limitations.
 *
 * The Original Code is the cairo graphics library.
 *
 * The Initial Developer of the Original Code is Intel Corporation.
 *
 * Contributor(s):
 *	Eric Anholt <eric@anholt.net>
 *	Carl Worth <cworth@cworth.org>
 */

#include "cairo-glsl-private.h"
#include "cairo-gl-private.h"

static void
_cairo_glsl_transform_uniforms_init (cairo_glsl_transform_uniforms_t *uniforms,
				     GLint prog)
{
    uniforms->x_bias = glGetUniformLocationARB (prog, "x_bias");
    uniforms->x_scale = glGetUniformLocationARB (prog, "x_scale");
    uniforms->y_bias = glGetUniformLocationARB (prog, "y_bias");
    uniforms->y_scale = glGetUniformLocationARB (prog, "y_scale");
}

/* We don't use a full matrix for our transformations because it's
 * wasteful when all we want is to rescale to NDC and possibly do a flip
 * if it's the front buffer.
 */
static void
_cairo_glsl_transform_uniforms_set_for_surface (cairo_glsl_transform_uniforms_t *uniforms,
						cairo_gl_surface_t *surface)
{
    int onscreen = (surface->fb == 0);

    glUniform1fARB (uniforms->x_bias, -surface->width / 2.0f);
    glUniform1fARB (uniforms->x_scale, 2.0f / surface->width);
    glUniform1fARB (uniforms->y_bias, -surface->height / 2.0f);

    if (onscreen)
	glUniform1fARB(uniforms->y_scale,
		       -2.0f / surface->height);
    else
	glUniform1fARB(uniforms->y_scale,
		       2.0f / surface->height);
}

static cairo_status_t
_cairo_glsl_link (GLint prog)
{
    GLint ok;

    glLinkProgram (prog);

    glGetObjectParameterivARB (prog, GL_OBJECT_LINK_STATUS_ARB, &ok);
    if (!ok) {
#if CAIRO_DEBUG_GLSL
	GLchar *info;
	GLint size;

	glGetObjectParameterivARB (prog, GL_OBJECT_INFO_LOG_LENGTH_ARB, &size);
	info = malloc (size);

	glGetInfoLogARB (prog, size, NULL, info);
	fprintf (stderr, "Failed to link: %s\n", info);
#endif
	return CAIRO_STATUS_GLSL_PROGRAM_ERROR;
    }

    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_glsl_compile (GLenum type, const char *source, GLint *prog_ret)
{
    GLint ok;
    GLint prog;

    prog = glCreateShaderObjectARB (type);
    glShaderSourceARB (prog, 1, (const GLchar **)&source, NULL);
    glCompileShaderARB (prog);

    glGetObjectParameterivARB (prog, GL_OBJECT_COMPILE_STATUS_ARB, &ok);
    if (!ok) {
#if CAIRO_DEBUG_GLSL
	GLchar *info;
	GLint size;

	glGetObjectParameterivARB (prog, GL_OBJECT_INFO_LOG_LENGTH_ARB, &size);
	info = malloc (size);

	glGetInfoLogARB (prog, size, NULL, info);
	fprintf (stderr, "Failed to compile %s: %s\n",
		 type == GL_FRAGMENT_SHADER ? "FS" : "VS",
		 info);
	fprintf (stderr, "Program source:\n%s", source);
#endif
	return CAIRO_STATUS_GLSL_PROGRAM_ERROR;
    }

    *prog_ret = prog;
    return CAIRO_STATUS_SUCCESS;
}

static cairo_status_t
_cairo_glsl_shader_solid_init (cairo_glsl_shader_solid_t *solid)
{
    cairo_status_t status;

    const char *solid_vs_only =
	"uniform vec4 color;\n"
	"uniform float x_bias;\n"
	"uniform float x_scale;\n"
	"uniform float y_bias;\n"
	"uniform float y_scale;\n"
	"void main()\n"
	"{\n"
	"	gl_Position = vec4((gl_Vertex.x + x_bias) * x_scale,\n"
	"			   (gl_Vertex.y + y_bias) * y_scale,\n"
	"			   0,\n"
	"			   1);\n"
	"	gl_Color = color;\n"
	"}\n";
    const char *solid_vs =
	"uniform float x_bias;\n"
	"uniform float x_scale;\n"
	"uniform float y_bias;\n"
	"uniform float y_scale;\n"
	"void main()\n"
	"{\n"
	"	gl_Position = vec4((gl_Vertex.x + x_bias) * x_scale,\n"
	"			   (gl_Vertex.y + y_bias) * y_scale,\n"
	"			   0,\n"
	"			   1);\n"
	"}\n";
    const char *solid_fs =
	"uniform vec4 color;\n"
	"void main()\n"
	"{\n"
	"	gl_FragColor = color;\n"
	"}\n";
    GLint fs_prog, vs_prog;

    solid->prog = glCreateProgramObjectARB ();
    if (GLEW_ARB_fragment_shader) {
	status = _cairo_glsl_compile (GL_VERTEX_SHADER_ARB,
				      solid_vs, &vs_prog);
	if (status)
	    return status;

	status = _cairo_glsl_compile (GL_FRAGMENT_SHADER_ARB,
				      solid_fs, &fs_prog);
	if (status)
	    return status;

	glAttachObjectARB (solid->prog, vs_prog);
	glAttachObjectARB (solid->prog, fs_prog);
    } else {
	status = _cairo_glsl_compile (GL_VERTEX_SHADER_ARB,
				      solid_vs_only, &vs_prog);
	if (status)
	    return status;

	glAttachObjectARB (solid->prog, vs_prog);
    }
    status = _cairo_glsl_link (solid->prog);
    if (status)
	return status;

    solid->color_uniform_location =
	glGetUniformLocationARB (solid->prog, "color");
    _cairo_glsl_transform_uniforms_init (&solid->uniforms, solid->prog);

    return CAIRO_STATUS_SUCCESS;
}

void
_cairo_glsl_shaders_init (cairo_glsl_shaders_t *shaders)
{
    _cairo_glsl_shader_solid_init (&shaders->solid);
}

cairo_int_status_t
_cairo_glsl_fill_rectangles (void			*abstract_surface,
			     cairo_operator_t		 op,
			     const cairo_color_t	*cairo_color,
			     cairo_rectangle_int_t	*rects,
			     int			 num_rects)
{
    cairo_gl_surface_t *surface = abstract_surface;
    cairo_gl_context_t *ctx;
    cairo_glsl_shader_solid_t *solid;
    GLfloat gl_color[4];
    int i;

    if (! _cairo_gl_operator_is_supported (op))
	return CAIRO_INT_STATUS_UNSUPPORTED;

    ctx = _cairo_gl_context_acquire (surface->ctx);
    solid = &ctx->shaders.solid;

    _cairo_gl_set_destination (surface);
    _cairo_gl_set_operator (surface, op);

    glUseProgramObjectARB (solid->prog);

    gl_color[0] = cairo_color->red * cairo_color->alpha;
    gl_color[1] = cairo_color->green * cairo_color->alpha;
    gl_color[2] = cairo_color->blue * cairo_color->alpha;
    gl_color[3] = cairo_color->alpha;

    glUniform4fvARB (solid->color_uniform_location, 1, gl_color);

    _cairo_glsl_transform_uniforms_set_for_surface (&solid->uniforms,
						    surface);

    glBegin (GL_TRIANGLES);
    for (i = 0; i < num_rects; i++) {
	glVertex2f (rects[i].x, rects[i].y);
	glVertex2f (rects[i].x + rects[i].width, rects[i].y);
	glVertex2f (rects[i].x + rects[i].width, rects[i].y + rects[i].height);
	glVertex2f (rects[i].x, rects[i].y);
	glVertex2f (rects[i].x, rects[i].y + rects[i].height);
	glVertex2f (rects[i].x + rects[i].width, rects[i].y + rects[i].height);
    }
    glEnd();

    glUseProgramObjectARB (0);

    _cairo_gl_context_release (ctx);

    return CAIRO_STATUS_SUCCESS;
}