qemu/ui/shader.c

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/*
* QEMU opengl shader helper functions
*
* Copyright (c) 2014 Red Hat
*
* Authors:
* Gerd Hoffmann <kraxel@redhat.com>
*
* 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
* THE AUTHORS OR COPYRIGHT HOLDERS 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.
*/
#include "qemu-common.h"
#include "ui/shader.h"
/* ---------------------------------------------------------------------- */
GLuint qemu_gl_init_texture_blit(GLint texture_blit_prog)
{
static const GLfloat in_position[] = {
-1, -1,
1, -1,
-1, 1,
1, 1,
};
GLint l_position;
GLuint vao, buffer;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
/* this is the VBO that holds the vertex data */
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(in_position), in_position,
GL_STATIC_DRAW);
l_position = glGetAttribLocation(texture_blit_prog, "in_position");
glVertexAttribPointer(l_position, 2, GL_FLOAT, GL_FALSE, 0, 0);
glEnableVertexAttribArray(l_position);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindVertexArray(0);
return vao;
}
void qemu_gl_run_texture_blit(GLint texture_blit_prog,
GLint texture_blit_vao)
{
glUseProgram(texture_blit_prog);
glBindVertexArray(texture_blit_vao);
glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
}
/* ---------------------------------------------------------------------- */
GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src)
{
GLuint shader;
GLint status, length;
char *errmsg;
shader = glCreateShader(type);
glShaderSource(shader, 1, &src, 0);
glCompileShader(shader);
glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
if (!status) {
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
errmsg = malloc(length);
glGetShaderInfoLog(shader, length, &length, errmsg);
fprintf(stderr, "%s: compile %s error\n%s\n", __func__,
(type == GL_VERTEX_SHADER) ? "vertex" : "fragment",
errmsg);
free(errmsg);
return 0;
}
return shader;
}
GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag)
{
GLuint program;
GLint status, length;
char *errmsg;
program = glCreateProgram();
glAttachShader(program, vert);
glAttachShader(program, frag);
glLinkProgram(program);
glGetProgramiv(program, GL_LINK_STATUS, &status);
if (!status) {
glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
errmsg = malloc(length);
glGetProgramInfoLog(program, length, &length, errmsg);
fprintf(stderr, "%s: link program: %s\n", __func__, errmsg);
free(errmsg);
return 0;
}
return program;
}
GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
const GLchar *frag_src)
{
GLuint vert_shader, frag_shader, program;
vert_shader = qemu_gl_create_compile_shader(GL_VERTEX_SHADER, vert_src);
frag_shader = qemu_gl_create_compile_shader(GL_FRAGMENT_SHADER, frag_src);
if (!vert_shader || !frag_shader) {
return 0;
}
program = qemu_gl_create_link_program(vert_shader, frag_shader);
glDeleteShader(vert_shader);
glDeleteShader(frag_shader);
return program;
}