initial commit

1 files changed, 118 insertions, 0 deletions

diff --git a/src/shader.zig b/src/shader.zig
new file mode 100644
index 0000000..ed36035
--- /dev/null
+++ b/src/shader.zig
@@ -0,0 +1,118 @@
+const std = @import("std");
+const panic = std.debug.panic
+const c = @import("c.zig");
+
+
+pub const ShaderProgram = struct {
+    program_id: c.GLuint,
+    vertex_id: c.GLuint,
+    fragment_id: c.GLuint,
+    maybe_geometry_id: ?c.GLuint,
+
+    pub fn bind(sp: ShaderProgram) void {
+        c.glUseProgram(sp.program_id);
+    }
+
+    pub fn attribLocation(sp: ShaderProgram, name: [*]const u8) c.GLint {
+        const id = c.glGetAttribLocation(sp.program_id, name);
+        if (id == -1) {
+            panic("invalid attrib: {}\n", .{name});
+        }
+        return id;
+    }
+
+    pub fn uniformLocation(sp: ShaderProgram, name: [*]const u8) c.GLint {
+        const id = c.glGetUniformLocation(sp.program_id, name);
+        if (id == -1) {
+            panic("invalid uniform: {}\n", .{name});
+        }
+        return id;
+    }
+
+    pub fn setUniformInt(sp: ShaderProgram, uniform_id: c.GLint, value: c_int) void {
+        c.glUniform1i(uniform_id, value);
+    }
+
+    pub fn setUniformFloat(sp: ShaderProgram, uniform_id: c.GLint, value: f32) void {
+        c.glUniform1f(uniform_id, value);
+    }
+
+    pub fn setUniformVec3(sp: ShaderProgram, uniform_id: c.GLint, value: math3d.Vec3) void {
+        c.glUniform3fv(uniform_id, 1, value.data[0..].ptr);
+    }
+
+    pub fn setUniformVec4(sp: ShaderProgram, uniform_id: c.GLint, value: Vec4) void {
+        c.glUniform4fv(uniform_id, 1, value.data[0..].ptr);
+    }
+
+    pub fn setUniformMat4x4(sp: ShaderProgram, uniform_id: c.GLint, value: Mat4x4) void {
+        c.glUniformMatrix4fv(uniform_id, 1, c.GL_FALSE, value.data[0][0..].ptr);
+    }
+
+    pub fn create(
+        vertex_source: []const u8,
+        frag_source: []const u8,
+        maybe_geometry_source: ?[]u8,
+    ) !ShaderProgram {
+        var sp: ShaderProgram = undefined;
+        sp.vertex_id = try initGlShader(vertex_source, "vertex", c.GL_VERTEX_SHADER);
+        sp.fragment_id = try initGlShader(frag_source, "fragment", c.GL_FRAGMENT_SHADER);
+        sp.maybe_geometry_id = if (maybe_geometry_source) |geo_source|
+            try initGlShader(geo_source, "geometry", c.GL_GEOMETRY_SHADER)
+        else
+            null;
+
+        sp.program_id = c.glCreateProgram();
+        c.glAttachShader(sp.program_id, sp.vertex_id);
+        c.glAttachShader(sp.program_id, sp.fragment_id);
+        if (sp.maybe_geometry_id) |geo_id| {
+            c.glAttachShader(sp.program_id, geo_id);
+        }
+        c.glLinkProgram(sp.program_id);
+
+        var ok: c.GLint = undefined;
+        c.glGetProgramiv(sp.program_id, c.GL_LINK_STATUS, &ok);
+        if (ok != 0) return sp;
+
+        var error_size: c.GLint = undefined;
+        c.glGetProgramiv(sp.program_id, c.GL_INFO_LOG_LENGTH, &error_size);
+        const message = try c_allocator.alloc(u8, @intCast(usize, error_size));
+        c.glGetProgramInfoLog(sp.program_id, error_size, &error_size, message.ptr);
+        panic("Error linking shader program: {}\n", .{message.ptr});
+    }
+
+    pub fn destroy(sp: *ShaderProgram) void {
+        if (sp.maybe_geometry_id) |geo_id| {
+            c.glDetachShader(sp.program_id, geo_id);
+        }
+        c.glDetachShader(sp.program_id, sp.fragment_id);
+        c.glDetachShader(sp.program_id, sp.vertex_id);
+
+        if (sp.maybe_geometry_id) |geo_id| {
+            c.glDeleteShader(geo_id);
+        }
+        c.glDeleteShader(sp.fragment_id);
+        c.glDeleteShader(sp.vertex_id);
+
+        c.glDeleteProgram(sp.program_id);
+    }
+};
+
+fn initGlShader(source: []const u8, name: [*]const u8, kind: c.GLenum) !c.GLuint {
+    const shader_id = c.glCreateShader(kind);
+    const source_ptr: ?[*]const u8 = source.ptr;
+    const source_len = @intCast(c.GLint, source.len);
+    c.glShaderSource(shader_id, 1, &source_ptr, &source_len);
+    c.glCompileShader(shader_id);
+
+    var ok: c.GLint = undefined;
+    c.glGetShaderiv(shader_id, c.GL_COMPILE_STATUS, &ok);
+    if (ok != 0) return shader_id;
+
+    var error_size: c.GLint = undefined;
+    c.glGetShaderiv(shader_id, c.GL_INFO_LOG_LENGTH, &error_size);
+
+    const message = try c_allocator.alloc(u8, @intCast(usize, error_size));
+    c.glGetShaderInfoLog(shader_id, error_size, &error_size, message.ptr);
+    panic("Error compiling {} shader:\n{}\n", .{ name, message.ptr });
+}