win_opengl: Split shader loading to it's own file.

src/win/win_opengl_glslp.c

@@ -0,0 +1,224 @@
+/*
+ * 86Box	A hypervisor and IBM PC system emulator that specializes in
+ *		running old operating systems and software designed for IBM
+ *		PC systems and compatibles from 1981 through fairly recent
+ *		system designs based on the PCI bus.
+ *
+ *		This file is part of the 86Box distribution.
+ *
+ *		File parser for .glslp and .glsl shader files
+ *		in the format of libretro.
+ *
+ * TODO:	Read .glslp files for multipass shaders and settings.
+ *
+ * Authors:	Teemu Korhonen
+ *
+ *		Copyright 2021 Teemu Korhonen
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+#include <glad/glad.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <86box/86box.h>
+#include <86box/plat.h>
+#include <86box/win_opengl_glslp.h>
+
+ /**
+  * @brief Default vertex shader.
+ */
+static const GLchar* vertex_shader = "#version 330 core\n\
+in vec2 VertexCoord;\n\
+in vec2 TexCoord;\n\
+out vec2 tex;\n\
+void main(){\n\
+	gl_Position = vec4(VertexCoord, 0.0, 1.0);\n\
+	tex = TexCoord;\n\
+}\n";
+
+/**
+ * @brief Default fragment shader.
+ */
+static const GLchar* fragment_shader = "#version 330 core\n\
+in vec2 tex;\n\
+uniform sampler2D texsampler;\n\
+void main() {\n\
+	gl_FragColor = texture(texsampler, tex);\n\
+}\n";
+
+/**
+ * @brief Reads a whole file into a null terminated string.
+ * @param Path Path to the file relative to executable path.
+ * @return Pointer to the string or NULL on error. Remember to free() after use.
+*/
+static char* read_file_to_string(const char* path)
+{
+	char* full_path = (char*)malloc(sizeof(char) * (strlen(path) + strlen(exe_path) + 1));
+
+	plat_append_filename(full_path, exe_path, path);
+
+	FILE* file_handle = plat_fopen(full_path, "rb");
+
+	free(full_path);
+
+	if (file_handle != NULL)
+	{
+		/* get file size */
+		fseek(file_handle, 0, SEEK_END);
+		long file_size = ftell(file_handle);
+		fseek(file_handle, 0, SEEK_SET);
+
+		/* read to buffer and close */
+		char* content = (char*)malloc(sizeof(char) * (file_size + 1));
+		size_t length = fread(content, sizeof(char), file_size, file_handle);
+		fclose(file_handle);
+		content[length] = 0;
+
+		return content;
+	}
+	return NULL;
+}
+
+/**
+ * @brief Compile custom shaders into a program.
+ * @return Shader program identifier.
+*/
+GLuint load_custom_shaders()
+{
+	GLint status = GL_FALSE;
+	int info_log_length;
+
+	/* TODO: get path from config */
+	char* shader = read_file_to_string("shaders/shader.glsl");
+
+	if (shader != NULL)
+	{
+		int success = 1;
+
+		const char* vertex_sources[2] = { "#define VERTEX\n", shader };
+		const char* fragment_sources[2] = { "#define FRAGMENT\n", shader };
+
+		GLuint vertex_id = glCreateShader(GL_VERTEX_SHADER);
+		GLuint fragment_id = glCreateShader(GL_FRAGMENT_SHADER);
+
+		glShaderSource(vertex_id, 2, vertex_sources, NULL);
+		glCompileShader(vertex_id);
+		glGetShaderiv(vertex_id, GL_COMPILE_STATUS, &status);
+
+		if (status == GL_FALSE)
+		{
+			glGetShaderiv(vertex_id, GL_INFO_LOG_LENGTH, &info_log_length);
+
+			GLchar* info_log_text = (GLchar*)malloc(sizeof(GLchar) * info_log_length);
+
+			glGetShaderInfoLog(vertex_id, info_log_length, NULL, info_log_text);
+
+			/* TODO: error logging */
+
+			free(info_log_text);
+
+			success = 0;
+		}
+
+		glShaderSource(fragment_id, 2, fragment_sources, NULL);
+		glCompileShader(fragment_id);
+		glGetShaderiv(fragment_id, GL_COMPILE_STATUS, &status);
+
+		if (status == GL_FALSE)
+		{
+			glGetShaderiv(fragment_id, GL_INFO_LOG_LENGTH, &info_log_length);
+
+			GLchar* info_log_text = (GLchar*)malloc(sizeof(GLchar) * info_log_length);
+
+			glGetShaderInfoLog(fragment_id, info_log_length, NULL, info_log_text);
+
+			/* TODO: error logging */
+
+			free(info_log_text);
+
+			success = 0;
+		}
+
+		free(shader);
+
+		GLuint prog_id = 0;
+
+		if (success)
+		{
+			prog_id = glCreateProgram();
+
+			glAttachShader(prog_id, vertex_id);
+			glAttachShader(prog_id, fragment_id);
+			glLinkProgram(prog_id);
+			glGetProgramiv(prog_id, GL_LINK_STATUS, &status);
+
+			if (status == GL_FALSE)
+			{
+				glGetProgramiv(prog_id, GL_INFO_LOG_LENGTH, &info_log_length);
+
+				GLchar* info_log_text = (GLchar*)malloc(sizeof(GLchar) * info_log_length);
+
+				glGetProgramInfoLog(prog_id, info_log_length, NULL, info_log_text);
+
+				/* TODO: error logging */
+
+				free(info_log_text);
+			}
+
+			glDetachShader(prog_id, vertex_id);
+			glDetachShader(prog_id, fragment_id);
+		}
+
+		glDeleteShader(vertex_id);
+		glDeleteShader(fragment_id);
+
+		return prog_id;
+	}
+	return 0;
+}
+
+/**
+ * @brief Compile default shaders into a program.
+ * @return Shader program identifier.
+*/
+GLuint load_default_shaders()
+{
+	GLuint vertex_id = glCreateShader(GL_VERTEX_SHADER);
+	GLuint fragment_id = glCreateShader(GL_FRAGMENT_SHADER);
+
+	glShaderSource(vertex_id, 1, &vertex_shader, NULL);
+	glCompileShader(vertex_id);
+
+	glShaderSource(fragment_id, 1, &fragment_shader, NULL);
+	glCompileShader(fragment_id);
+
+	GLuint prog_id = glCreateProgram();
+
+	glAttachShader(prog_id, vertex_id);
+	glAttachShader(prog_id, fragment_id);
+
+	glLinkProgram(prog_id);
+
+	glDetachShader(prog_id, vertex_id);
+	glDetachShader(prog_id, fragment_id);
+
+	glDeleteShader(vertex_id);
+	glDeleteShader(fragment_id);
+
+	return prog_id;
+}