1 files changed, 203 insertions, 0 deletions
diff --git a/platform/gl/gl.c b/platform/gl/gl.c
new file mode 100644
index 0000000..915c37c
--- /dev/null
+++ b/platform/gl/gl.c
@@ -0,0 +1,203 @@
+// The OpenGL platform. Uses GLFW for an interface with the OS. The code
+// quality here is meh. Things could be organized more into functions, but as
+// for now, it works fine, and isn't worth improving immediately.
+
+#include <GLFW/glfw3.h>
+#include <glad/glad.h>
+
+#include "common.h"
+#include "teensy.h"
+#include "platform.h"
+
+static char vert[] =
+    "#version 330 core\n"
+    "layout (location = 0) in vec2 v_pos;\n"
+    "layout (location = 1) in vec2 v_uv;\n"
+    "\n"
+    "out vec2 f_uv;\n"
+    "\n"
+    "void main() {\n"
+    "    gl_Position = vec4(v_pos, 0.0, 1.0);\n"
+    "    f_uv = v_uv;\n"
+    "}\n"
+;
+
+static char frag[] =
+    "#version 330 core\n"
+    "\n"
+    "in vec2 f_uv;\n"
+    "\n"
+    "out vec4 color;\n"
+    "\n"
+    "uniform sampler2D tex;\n"
+    "\n"
+    "void main() {\n"
+    "    color = texture2D(tex, f_uv);\n"
+    "}\n"
+;
+
+struct gl_platform {
+    GLFWwindow *win;
+    GLuint vao;
+    GLuint vbo;
+    GLuint program;
+    GLint uniform_tex_loc;
+    GLuint screen_handle;
+};
+
+struct gl_platform p;
+
+static
+GLuint compile_shader(GLenum type, const char *src)
+{
+    GLuint shader = glCreateShader(type);
+    glShaderSource(shader, 1, &src, NULL);
+    glCompileShader(shader);
+
+    int ok;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, &ok);
+    if (!ok) {
+        char msg[1024];
+        glGetShaderInfoLog(shader, 1024, NULL, msg);
+        ty_log_fatal(TY_PLATFORM_ERR, "failed to compile shader: %s", msg);
+    }
+
+    return shader;
+}
+
+void ty_platform_init(struct ty_ctx *ctx)
+{
+    if (glfwInit() < 0)
+        ty_log_fatal(TY_PLATFORM_ERR, "Could not init GLFW");
+
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+    glfwWindowHint(GLFW_RESIZABLE, GLFW_FALSE);
+
+    p.win = glfwCreateWindow(
+        ctx->creation_hints.win_width,
+        ctx->creation_hints.win_height,
+        ctx->creation_hints.win_title,
+        NULL,
+        NULL
+    );
+
+    if (!p.win)
+        ty_log_fatal(TY_PLATFORM_ERR, "Could not init GLFW window");
+
+    glfwMakeContextCurrent(p.win);
+
+    if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
+        ty_log_fatal(TY_PLATFORM_ERR, "Could not init GLAD");
+
+    struct ty_vec2 vertices[] = {
+        ty_vec2(-1, -1), ty_vec2(0, 1),
+        ty_vec2( 1, -1), ty_vec2(1, 1),
+        ty_vec2( 1,  1), ty_vec2(1, 0),
+                                         
+        ty_vec2(-1, -1), ty_vec2(0, 1),
+        ty_vec2( 1,  1), ty_vec2(1, 0),
+        ty_vec2(-1,  1), ty_vec2(0, 0),
+    };
+    
+    glGenTextures(1, &p.screen_handle);
+    glBindTexture(GL_TEXTURE_2D, p.screen_handle);
+
+    glGenVertexArrays(1, &p.vao);
+    glGenBuffers(1, &p.vbo);
+
+    glBindVertexArray(p.vao);
+
+    glBindBuffer(GL_ARRAY_BUFFER, p.vbo);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+    glVertexAttribPointer(
+        0,
+        2, GL_FLOAT,
+        GL_FALSE,
+        sizeof(struct ty_vec2) * 2, (void*)0
+    );
+    glEnableVertexAttribArray(0);
+    glVertexAttribPointer(
+        1,
+        2, GL_FLOAT,
+        GL_FALSE,
+        sizeof(struct ty_vec2) * 2, (void*)sizeof(struct ty_vec2)
+    );
+    glEnableVertexAttribArray(1);
+
+    p.program = glCreateProgram();
+    GLuint vert_sh = compile_shader(GL_VERTEX_SHADER, vert);
+    GLuint frag_sh = compile_shader(GL_FRAGMENT_SHADER, frag);
+    glAttachShader(p.program, vert_sh);
+    glAttachShader(p.program, frag_sh);
+    glLinkProgram(p.program);
+
+    glDeleteShader(vert_sh);
+    glDeleteShader(frag_sh);
+
+    int ok;
+    glGetProgramiv(p.program, GL_LINK_STATUS, &ok);
+    if (!ok) {
+        char msg[1024];
+        glGetProgramInfoLog(p.program, 1024, NULL, msg);
+        ty_log_fatal(TY_PLATFORM_ERR, "failed to link shaders: %s", msg);
+    }
+
+    p.uniform_tex_loc = glGetUniformLocation(p.program, "texture");
+}
+
+void ty_platform_deinit(void)
+{
+    glfwDestroyWindow(p.win);
+    glfwTerminate();
+}
+
+void ty_platform_frame(struct ty_image img)
+{
+    glfwPollEvents();
+
+    int win_width, win_height;
+    glfwGetWindowSize(p.win, &win_width, &win_height);
+
+    glViewport(0, 0, win_width, win_height);
+
+    glActiveTexture(GL_TEXTURE0);
+    glBindTexture(GL_TEXTURE_2D, p.screen_handle);
+    glTexImage2D(
+        GL_TEXTURE_2D,
+        0,
+        GL_RGB,
+        img.width, img.height,
+        0,
+        GL_RGB,
+        GL_UNSIGNED_BYTE,
+        img.data
+    );
+    glGenerateMipmap(GL_TEXTURE_2D);
+
+    glClearColor(0, 0, 0, 1);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    glUseProgram(p.program);
+    glUniform1i(p.uniform_tex_loc, 0);
+
+    glBindVertexArray(p.vao);
+    glDrawArrays(GL_TRIANGLES, 0, 6);
+
+    glfwSwapBuffers(p.win);
+
+    if (glfwGetKey(p.win, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
+        glfwSetWindowShouldClose(p.win, true);
+    }
+}
+
+bool ty_platform_os_wants_quit(void)
+{
+    return glfwWindowShouldClose(p.win);
+}
+
+double ty_platform_get_time(void)
+{
+    return glfwGetTime();
+}