lib/gamnit: add a portable version of the triangle example

[nit.git] / lib / gamnit / examples / triangle / src / portable_triangle.nit

diff --git a/lib/gamnit/examples/triangle/src/portable_triangle.nit b/lib/gamnit/examples/triangle/src/portable_triangle.nit
new file mode 100644 (file)
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+++ b/lib/gamnit/examples/triangle/src/portable_triangle.nit
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+# This file is part of NIT ( http://www.nitlanguage.org ).
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Portable example of using Gamnit with custom calls to OpenGL ES 2.0
+#
+# References:
+# * The book OpenGL ES 2.0 Programming Guide
+# * https://code.google.com/p/opengles-book-samples/source/browse/trunk/LinuxX11/Chapter_2/Hello_Triangle/Hello_Triangle.c
+module portable_triangle is
+       app_name "gamnit Triangle"
+       app_namespace "org.nitlanguage.triangle"
+       app_version(1, 0, git_revision)
+end
+
+import gamnit
+
+redef class App
+
+       # Our only program for the graphic card
+       var program: GLProgram is noautoinit
+
+       # The only vertex sharder
+       var vertex_shader: GLVertexShader is noautoinit
+
+       # The only fragment sharder
+       var fragment_shader: GLFragmentShader is noautoinit
+
+       # Vertex data for the triangle
+       var vertex_array: VertexArray is noautoinit
+
+       redef fun on_create
+       do
+               super
+
+               var display = display
+               assert display != null
+
+               print "Width: {display.width}"
+               print "Height: {display.height}"
+
+               assert_no_gl_error
+               assert gl.shader_compiler else print "Cannot compile shaders"
+
+               # GL program
+               program = new GLProgram
+               if not program.is_ok then
+                       print "Program is not ok: {gl.error.to_s}\nLog:"
+                       print program.info_log
+                       abort
+               end
+               assert_no_gl_error
+
+               # Vertex shader
+               vertex_shader = new GLVertexShader
+               assert vertex_shader.is_ok else print "Vertex shader is not ok: {gl.error}"
+               vertex_shader.source = """
+               attribute vec4 vPosition;
+               void main()
+               {
+                 gl_Position = vPosition;
+               }
+               """@glsl_vertex_shader.to_cstring
+               vertex_shader.compile
+               assert vertex_shader.is_compiled else print "Vertex shader compilation failed with: {vertex_shader.info_log} {program.info_log}"
+               assert_no_gl_error
+
+               # Fragment shader
+               fragment_shader = new GLFragmentShader
+               assert fragment_shader.is_ok else print "Fragment shader is not ok: {gl.error}"
+               fragment_shader.source = """
+               precision mediump float;
+               void main()
+               {
+                       gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
+               }
+               """@glsl_fragment_shader.to_cstring
+               fragment_shader.compile
+               assert fragment_shader.is_compiled else print "Fragment shader compilation failed with: {fragment_shader.info_log}"
+               assert_no_gl_error
+
+               # Attach to program
+               program.attach_shader vertex_shader
+               program.attach_shader fragment_shader
+               program.bind_attrib_location(0, "vPosition")
+               program.link
+               assert program.is_linked else print "Linking failed: {program.info_log}"
+               assert_no_gl_error
+
+               # Draw!
+               var vertices = [0.0, 0.5, 0.0, -0.5, -0.5, 0.0, 0.5, -0.5, 0.0]
+               vertex_array = new VertexArray(0, 3, vertices)
+               vertex_array.attrib_pointer
+       end
+
+       redef fun frame_core
+       do
+               var display = display
+               if display != null then
+                       gl.clear_color(0.5, 0.0, 0.5, 1.0)
+
+                       assert_no_gl_error
+                       gl.viewport(0, 0, display.width, display.height)
+                       gl.clear((new GLBuffer).color)
+                       program.use
+                       vertex_array.enable
+
+                       glDrawArrays(new GLDrawMode.triangles, 0, 3)
+
+                       display.flip
+               end
+       end
+
+       redef fun on_stop
+       do
+               # Clean up
+               program.delete
+               vertex_shader.delete
+               fragment_shader.delete
+
+               # Close gamnit
+               var display = display
+               if display != null then display.close
+       end
+end
+
+if "NIT_TESTING".environ == "true" then exit(0)
+super