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/osdep.h"
  28 #include "qemu-common.h"
  29 #include "ui/shader.h"
  30
  31 /* ---------------------------------------------------------------------- */
  32
  33 GLuint qemu_gl_init_texture_blit(GLint texture_blit_prog)
  34 {
  35     static const GLfloat in_position[] = {
  36         -1, -1,
  37         1,  -1,
  38         -1,  1,
  39         1,   1,
  40     };
  41     GLint l_position;
  42     GLuint vao, buffer;
  43
  44     glGenVertexArrays(1, &vao);
  45     glBindVertexArray(vao);
  46
  47     /* this is the VBO that holds the vertex data */
  48     glGenBuffers(1, &buffer);
  49     glBindBuffer(GL_ARRAY_BUFFER, buffer);
  50     glBufferData(GL_ARRAY_BUFFER, sizeof(in_position), in_position,
  51                  GL_STATIC_DRAW);
  52
  53     l_position = glGetAttribLocation(texture_blit_prog, "in_position");
  54     glVertexAttribPointer(l_position, 2, GL_FLOAT, GL_FALSE, 0, 0);
  55     glEnableVertexAttribArray(l_position);
  56
  57     glBindBuffer(GL_ARRAY_BUFFER, 0);
  58     glBindVertexArray(0);
  59
  60     return vao;
  61 }
  62
  63 void qemu_gl_run_texture_blit(GLint texture_blit_prog,
  64                               GLint texture_blit_vao)
  65 {
  66     glUseProgram(texture_blit_prog);
  67     glBindVertexArray(texture_blit_vao);
  68     glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
  69 }
  70
  71 /* ---------------------------------------------------------------------- */
  72
  73 GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src)
  74 {
  75     GLuint shader;
  76     GLint status, length;
  77     char *errmsg;
  78
  79     shader = glCreateShader(type);
  80     glShaderSource(shader, 1, &src, 0);
  81     glCompileShader(shader);
  82
  83     glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
  84     if (!status) {
  85         glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &length);
  86         errmsg = malloc(length);
  87         glGetShaderInfoLog(shader, length, &length, errmsg);
  88         fprintf(stderr, "%s: compile %s error\n%s\n", __func__,
  89                 (type == GL_VERTEX_SHADER) ? "vertex" : "fragment",
  90                 errmsg);
  91         free(errmsg);
  92         return 0;
  93     }
  94     return shader;
  95 }
  96
  97 GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag)
  98 {
  99     GLuint program;
 100     GLint status, length;
 101     char *errmsg;
 102
 103     program = glCreateProgram();
 104     glAttachShader(program, vert);
 105     glAttachShader(program, frag);
 106     glLinkProgram(program);
 107
 108     glGetProgramiv(program, GL_LINK_STATUS, &status);
 109     if (!status) {
 110         glGetProgramiv(program, GL_INFO_LOG_LENGTH, &length);
 111         errmsg = malloc(length);
 112         glGetProgramInfoLog(program, length, &length, errmsg);
 113         fprintf(stderr, "%s: link program: %s\n", __func__, errmsg);
 114         free(errmsg);
 115         return 0;
 116     }
 117     return program;
 118 }
 119
 120 GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
 121                                            const GLchar *frag_src)
 122 {
 123     GLuint vert_shader, frag_shader, program;
 124
 125     vert_shader = qemu_gl_create_compile_shader(GL_VERTEX_SHADER, vert_src);
 126     frag_shader = qemu_gl_create_compile_shader(GL_FRAGMENT_SHADER, frag_src);
 127     if (!vert_shader || !frag_shader) {
 128         return 0;
 129     }
 130
 131     program = qemu_gl_create_link_program(vert_shader, frag_shader);
 132     glDeleteShader(vert_shader);
 133     glDeleteShader(frag_shader);
 134
 135     return program;
 136 }