renderer/opengl: setup image uniforms

src/renderer/OpenGL.zig

@@ -22,6 +22,7 @@ const math = @import("../math.zig");
 const Surface = @import("../Surface.zig");
 
 const CellProgram = @import("opengl/CellProgram.zig");
+const ImageProgram = @import("opengl/ImageProgram.zig");
 const gl_image = @import("opengl/image.zig");
 const custom = @import("opengl/custom.zig");
 const Image = gl_image.Image;
@@ -148,17 +149,22 @@ const SetScreenSize = struct {
         );
 
         // Update the projection uniform within our shader
-        try gl_state.cell_program.program.setUniform(
-            "projection",
+        inline for (.{ "cell_program", "image_program" }) |name| {
+            const program = @field(gl_state, name);
+            const bind = try program.program.use();
+            defer bind.unbind();
+            try program.program.setUniform(
+                "projection",
 
-            // 2D orthographic projection with the full w/h
-            math.ortho2d(
-                -1 * @as(f32, @floatFromInt(padding.left)),
-                @floatFromInt(padded_size.width + padding.right),
-                @floatFromInt(padded_size.height + padding.bottom),
-                -1 * @as(f32, @floatFromInt(padding.top)),
-            ),
-        );
+                // 2D orthographic projection with the full w/h
+                math.ortho2d(
+                    -1 * @as(f32, @floatFromInt(padding.left)),
+                    @floatFromInt(padded_size.width + padding.right),
+                    @floatFromInt(padded_size.height + padding.bottom),
+                    -1 * @as(f32, @floatFromInt(padding.top)),
+                ),
+            );
+        }
 
         // Update our custom shader resolution
         if (gl_state.custom) |*custom_state| {
@@ -173,13 +179,21 @@ const SetFontSize = struct {
     fn apply(self: SetFontSize, r: *const OpenGL) !void {
         const gl_state = r.gl_state orelse return error.OpenGLUninitialized;
 
-        try gl_state.cell_program.program.setUniform(
-            "cell_size",
-            @Vector(2, f32){
-                @floatFromInt(self.metrics.cell_width),
-                @floatFromInt(self.metrics.cell_height),
-            },
-        );
+        inline for (.{ "cell_program", "image_program" }) |name| {
+            const program = @field(gl_state, name);
+            const bind = try program.program.use();
+            defer bind.unbind();
+            try program.program.setUniform(
+                "cell_size",
+                @Vector(2, f32){
+                    @floatFromInt(self.metrics.cell_width),
+                    @floatFromInt(self.metrics.cell_height),
+                },
+            );
+        }
+
+        const bind = try gl_state.cell_program.program.use();
+        defer bind.unbind();
         try gl_state.cell_program.program.setUniform(
             "strikethrough_position",
             @as(f32, @floatFromInt(self.metrics.strikethrough_position)),
@@ -1743,6 +1757,7 @@ fn drawCells(
 /// OpenGL context is replaced.
 const GLState = struct {
     cell_program: CellProgram,
+    image_program: ImageProgram,
     texture: gl.Texture,
     texture_color: gl.Texture,
     custom: ?custom.State,
@@ -1830,8 +1845,13 @@ const GLState = struct {
         const cell_program = try CellProgram.init();
         errdefer cell_program.deinit();
 
+        // Build our image renderer
+        const image_program = try ImageProgram.init();
+        errdefer image_program.deinit();
+
         return .{
             .cell_program = cell_program,
+            .image_program = image_program,
             .texture = tex,
             .texture_color = tex_color,
             .custom = custom_state,
@@ -1842,6 +1862,7 @@ const GLState = struct {
         if (self.custom) |v| v.deinit(alloc);
         self.texture.destroy();
         self.texture_color.destroy();
+        self.image_program.deinit();
         self.cell_program.deinit();
     }
 };

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();
+    }
+};

src/renderer/shaders/image.f.glsl

@@ -0,0 +1,11 @@
+#version 330 core
+
+in vec2 tex_coords;
+
+layout(location = 0) out vec4 out_FragColor;
+
+uniform sampler2D image;
+
+void main() {
+    out_FragColor = texture(image, tex_coords);
+}

src/renderer/shaders/image.v.glsl

@@ -0,0 +1,44 @@
+#version 330 core
+
+layout (location = 0) in vec2 grid_pos;
+layout (location = 1) in vec2 cell_offset;
+layout (location = 2) in vec4 source_rect;
+layout (location = 3) in vec2 dest_size;
+
+out vec2 tex_coord;
+
+uniform sampler2D image;
+uniform vec2 cell_size;
+uniform mat4 projection;
+
+void main() {
+    // The size of the image in pixels
+    vec2 image_size = textureSize(image, 0);
+
+    // Turn the cell position into a vertex point depending on the
+    // gl_VertexID. Since we use instanced drawing, we have 4 vertices
+    // for each corner of the cell. We can use gl_VertexID to determine
+    // which one we're looking at. Using this, we can use 1 or 0 to keep
+    // or discard the value for the vertex.
+    //
+    // 0 = top-right
+    // 1 = bot-right
+    // 2 = bot-left
+    // 3 = top-left
+    vec2 position;
+    position.x = (gl_VertexID == 0 || gl_VertexID == 1) ? 1. : 0.;
+    position.y = (gl_VertexID == 0 || gl_VertexID == 3) ? 0. : 1.;
+
+    // The texture coordinates start at our source x/y, then add the width/height
+    // as enabled by our instance id, then normalize to [0, 1]
+    tex_coord = source_rect.xy;
+    tex_coord += source_rect.zw * position;
+    tex_coord /= image_size;
+
+    // The position of our image starts at the top-left of the grid cell and
+    // adds the source rect width/height components.
+    vec2 image_pos = (cell_size * grid_pos) + cell_offset;
+    image_pos += dest_size * position;
+
+    gl_Position = projection * vec4(image_pos.xy, 0, 1.0);
+}