renderer/opengl: setup image uniforms

src/renderer/opengl/ImageProgram.zig

@@ -0,0 +1,134 @@
+/// The OpenGL program for rendering terminal cells.
+const ImageProgram = @This();
+
+const std = @import("std");
+const gl = @import("opengl");
+
+program: gl.Program,
+vao: gl.VertexArray,
+ebo: gl.Buffer,
+vbo: gl.Buffer,
+
+pub const Input = extern struct {
+    /// vec2 grid_coord
+    grid_col: u16,
+    grid_row: u16,
+
+    /// vec2 cell_offset
+    cell_offset_x: u32 = 0,
+    cell_offset_y: u32 = 0,
+
+    /// vec4 source_rect
+    source_x: u32 = 0,
+    source_y: u32 = 0,
+    source_width: u32 = 0,
+    source_height: u32 = 0,
+
+    /// vec2 dest_size
+    dest_width: u32 = 0,
+    dest_height: u32 = 0,
+};
+
+pub fn init() !ImageProgram {
+    // Load and compile our shaders.
+    const program = try gl.Program.createVF(
+        @embedFile("../shaders/image.v.glsl"),
+        @embedFile("../shaders/image.f.glsl"),
+    );
+    errdefer program.destroy();
+
+    // Set our program uniforms
+    const pbind = try program.use();
+    defer pbind.unbind();
+
+    // Set all of our texture indexes
+    try program.setUniform("image", 0);
+
+    // Setup our VAO
+    const vao = try gl.VertexArray.create();
+    errdefer vao.destroy();
+    const vaobind = try vao.bind();
+    defer vaobind.unbind();
+
+    // Element buffer (EBO)
+    const ebo = try gl.Buffer.create();
+    errdefer ebo.destroy();
+    var ebobind = try ebo.bind(.element_array);
+    defer ebobind.unbind();
+    try ebobind.setData([6]u8{
+        0, 1, 3, // Top-left triangle
+        1, 2, 3, // Bottom-right triangle
+    }, .static_draw);
+
+    // Vertex buffer (VBO)
+    const vbo = try gl.Buffer.create();
+    errdefer vbo.destroy();
+    var vbobind = try vbo.bind(.array);
+    defer vbobind.unbind();
+    var offset: usize = 0;
+    try vbobind.attributeAdvanced(0, 2, gl.c.GL_UNSIGNED_SHORT, false, @sizeOf(Input), offset);
+    offset += 2 * @sizeOf(u16);
+    try vbobind.attributeAdvanced(1, 2, gl.c.GL_UNSIGNED_INT, false, @sizeOf(Input), offset);
+    offset += 2 * @sizeOf(u32);
+    try vbobind.attributeAdvanced(2, 4, gl.c.GL_UNSIGNED_INT, false, @sizeOf(Input), offset);
+    offset += 4 * @sizeOf(u32);
+    try vbobind.attributeAdvanced(3, 2, gl.c.GL_UNSIGNED_INT, false, @sizeOf(Input), offset);
+    offset += 2 * @sizeOf(u32);
+    try vbobind.enableAttribArray(0);
+    try vbobind.enableAttribArray(1);
+    try vbobind.enableAttribArray(2);
+    try vbobind.enableAttribArray(3);
+    try vbobind.attributeDivisor(0, 1);
+    try vbobind.attributeDivisor(1, 1);
+    try vbobind.attributeDivisor(2, 1);
+    try vbobind.attributeDivisor(3, 1);
+
+    return .{
+        .program = program,
+        .vao = vao,
+        .ebo = ebo,
+        .vbo = vbo,
+    };
+}
+
+pub fn bind(self: ImageProgram) !Binding {
+    const program = try self.program.use();
+    errdefer program.unbind();
+
+    const vao = try self.vao.bind();
+    errdefer vao.unbind();
+
+    const ebo = try self.ebo.bind(.element_array);
+    errdefer ebo.unbind();
+
+    const vbo = try self.vbo.bind(.array);
+    errdefer vbo.unbind();
+
+    return .{
+        .program = program,
+        .vao = vao,
+        .ebo = ebo,
+        .vbo = vbo,
+    };
+}
+
+pub fn deinit(self: ImageProgram) void {
+    self.vbo.destroy();
+    self.ebo.destroy();
+    self.vao.destroy();
+    self.program.destroy();
+}
+
+pub const Binding = struct {
+    program: gl.Program.Binding,
+    vao: gl.VertexArray.Binding,
+    ebo: gl.Buffer.Binding,
+    vbo: gl.Buffer.Binding,
+
+    pub fn unbind(self: Binding) void {
+        self.vbo.unbind();
+        self.ebo.unbind();
+        self.vao.unbind();
+        self.program.unbind();
+    }
+};