ui/shader.c

   1 /*
   2  * QEMU opengl shader helper functions
   3  *
   4  * Copyright (c) 2014 Red Hat
   5  *
   6  * Authors:
   7  *    Gerd Hoffmann <kraxel@redhat.com>
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  22  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25  * THE SOFTWARE.
  26  */
  27 #include "qemu-common.h"
  28 #include "ui/shader.h"
  29
  30 /* ---------------------------------------------------------------------- */
  31
  32 GLuint qemu_gl_init_texture_blit(GLint texture_blit_prog)
  33 {
  34     static const GLfloat in_position[] = {
  35         -1, -1,
  36         1,  -1,
  37         -1,  1,
  38         1,   1,
  39     };
  40     GLint l_position;
  41     GLuint vao, buffer;
  42
  43     glGenVertexArrays(1, &vao);
  44     glBindVertexArray(vao);
  45
  46     /* this is the VBO that holds the vertex data */
  47     glGenBuffers(1, &buffer);
  48     glBindBuffer(GL_ARRAY_BUFFER, buffer);
  49     glBufferData(GL_ARRAY_BUFFER, sizeof(in_position), in_position,
  50                  GL_STATIC_DRAW);
  51
  52     l_position = glGetAttribLocation(texture_blit_prog, "in_position");
  53     glVertexAttribPointer(l_position, 2, GL_FLOAT, GL_FALSE, 0, 0);
  54     glEnableVertexAttribArray(l_position);
  55
  56     glBindBuffer(GL_ARRAY_BUFFER, 0);
  57     glBindVertexArray(0);
  58
  59     return vao;
  60 }
  61
  62 void qemu_gl_run_texture_blit(GLint texture_blit_prog,
  63                               GLint texture_blit_vao)
  64 {
  65     glUseProgram(texture_blit_prog);
  66     glBindVertexArray(texture_blit_vao);
  67     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
  68 }
  69
  70 /* ---------------------------------------------------------------------- */
  71
  72 GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src)
  73 {
  74     GLuint shader;
  75     GLint status, length;
  76     char *errmsg;
  77
  78     shader = glCreateShader(type);
  79     glShaderSource(shader, 1, &src, 0);
  80     glCompileShader(shader);
  81
  82     glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
  83     if (!status) {
  84         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
  85         errmsg = malloc(length);
  86         glGetShaderInfoLog(shader, length, &length, errmsg);
  87         fprintf(stderr, "%s: compile %s error\n%s\n", __func__,
  88                 (type == GL_VERTEX_SHADER) ? "vertex" : "fragment",
  89                 errmsg);
  90         free(errmsg);
  91         return 0;
  92     }
  93     return shader;
  94 }
  95
  96 GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag)
  97 {
  98     GLuint program;
  99     GLint status, length;
 100     char *errmsg;
 101
 102     program = glCreateProgram();
 103     glAttachShader(program, vert);
 104     glAttachShader(program, frag);
 105     glLinkProgram(program);
 106
 107     glGetProgramiv(program, GL_LINK_STATUS, &status);
 108     if (!status) {
 109         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
 110         errmsg = malloc(length);
 111         glGetProgramInfoLog(program, length, &length, errmsg);
 112         fprintf(stderr, "%s: link program: %s\n", __func__, errmsg);
 113         free(errmsg);
 114         return 0;
 115     }
 116     return program;
 117 }
 118
 119 GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
 120                                            const GLchar *frag_src)
 121 {
 122     GLuint vert_shader, frag_shader, program;
 123
 124     vert_shader = qemu_gl_create_compile_shader(GL_VERTEX_SHADER, vert_src);
 125     frag_shader = qemu_gl_create_compile_shader(GL_FRAGMENT_SHADER, frag_src);
 126     if (!vert_shader || !frag_shader) {
 127         return 0;
 128     }
 129
 130     program = qemu_gl_create_link_program(vert_shader, frag_shader);
 131     glDeleteShader(vert_shader);
 132     glDeleteShader(frag_shader);
 133
 134     return program;
 135 }