opengl: add shader helper functions.

Helper functions to compile, link and run opengl shader programs.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

include/ui/shader.h

+#ifdef CONFIG_OPENGL
+# include <GLES2/gl2.h>
+# include <GLES2/gl2ext.h>
+#endif
+
+GLuint qemu_gl_create_compile_shader(GLenum type, const GLchar *src);
+GLuint qemu_gl_create_link_program(GLuint vert, GLuint frag);
+GLuint qemu_gl_create_compile_link_program(const GLchar *vert_src,
+                                           const GLchar *frag_src);

ui/Makefile.objs

@@ -24,4 +24,11 @@ sdl.mo-objs := sdl2.o sdl2-input.o sdl2-2d.o
 endif
 sdl.mo-cflags := $(SDL_CFLAGS)
 
+ifeq ($(CONFIG_OPENGL),y)
+common-obj-y += shader.o
+endif
+
 gtk.o-cflags := $(GTK_CFLAGS) $(VTE_CFLAGS)
+shader.o-cflags += $(OPENGL_CFLAGS)
+
+shader.o-libs += $(OPENGL_LIBS)

ui/shader.c

+/*
+ * 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_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;
+}