A bunch more examples, focused in drawing and VBOs.

Mango0x45 · Aug 18, 2014 · 94827f3 · 94827f3
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Showing 6 changed files with 107 additions and 10 deletions.
diff --git a/html/examples/vbo_draw_indexed.htm b/html/examples/vbo_draw_indexed.htm
@@ -0,0 +1,28 @@
+// This definition is needed for type safety.
+#define BUFFER_OFFSET(i) ((char *)NULL + (i))
+
+{%glBindBuffer}(GL_ARRAY_BUFFER, vertex_buffer); // vertex_buffer is retrieved from {%glGenBuffers}
+{%glBindBuffer}(GL_ELEMENT_ARRAY_BUFFER, index_buffer); // index_buffer is retrieved from {%glGenBuffers}
+
+{%glEnableVertexAttribArray}(texcoord_attrib_index); // Attribute indexes were received from calls to {%glGetAttribLocation}, or passed into {%glBindAttribLocation}.
+{%glEnableVertexAttribArray}(normal_attrib_index);
+{%glEnableVertexAttribArray}(position_attrib_index);
+
+// vertex_stride is the size of bytes of each vertex in the buffer object
+// vertex_position_offset and kin are the offset in bytes of the position data
+// in each vertex. For example if your vertex structure is
+// [ position, texcoord, normal ] then position vertex_position_offset will
+// have offset 0, vertex_texcoord_offset is 12 (position is 3 * sizeof(float)
+// bytes large, and texcoord comes just after) and vertex_normal_offset is
+// 20 = 5 * sizeof(float).
+{%glVertexAttribPointer}(texcoord_attrib_index, 2, GL_FLOAT, false, vertex_stride, BUFFER_OFFSET(vertex_texcoord_offset));
+{%glVertexAttribPointer}(normal_attrib_index, 3, GL_FLOAT, false, vertex_stride, BUFFER_OFFSET(vertex_normal_offset));
+{%glVertexAttribPointer}(position_attrib_index, 3, GL_FLOAT, false, vertex_stride, BUFFER_OFFSET(vertex_position_offset));
+
+// num_vertices is the number of verts in your vertex_data.
+// index_data is an array of unsigned int offsets into vertex_data.
+{%glDrawElements}(GL_TRIANGLES, num_vertices, GL_UNSIGNED_INT, NULL);
+
+{%glDisableVertexAttribArray}(position_attrib_index);
+{%glDisableVertexAttribArray}(texcoord_attrib_index);
+{%glDisableVertexAttribArray}(normal_attrib_index);
diff --git a/html/examples/vbo_load.htm b/html/examples/vbo_load.htm
@@ -0,0 +1,19 @@
+// data_size_in_bytes is the size in bytes of your vertex data.
+// data_vertices is your actual vertex data, probably a huge array of floats
+
+GLuint vertex_buffer; // Save this for later rendering
+{%glGenBuffers}(1, &vertex_buffer);
+{%glBindBuffer}(GL_ARRAY_BUFFER, vertex_buffer);
+{%glBufferData}(GL_ARRAY_BUFFER, data_size_in_bytes, 0, GL_STATIC_DRAW);
+{%glBufferSubData}(GL_ARRAY_BUFFER, 0, data_size_in_bytes, data_vertices);
+
+GLint size = 0;
+{%glGetBufferParameteriv}(GL_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
+if(data_size_in_bytes != size)
+{
+	{%glDeleteBuffers}(1, &vertex_buffer);
+	// Log the error
+	return;
+}
+
+// Success
diff --git a/html/examples/vbo_load_index.htm b/html/examples/vbo_load_index.htm
@@ -0,0 +1,20 @@
+// data_size_in_bytes is the size in bytes of your vertex data.
+// data_indices is an array of integer offsets into your vertex data.
+
+GLuint index_buffer; // Save this for later rendering
+{%glGenBuffers}(1, &index_buffer);
+{%glBindBuffer}(GL_ELEMENT_ARRAY_BUFFER, index_buffer);
+{%glBufferData}(GL_ELEMENT_ARRAY_BUFFER, data_size_in_bytes, 0, GL_STATIC_DRAW);
+{%glBufferSubData}(GL_ELEMENT_ARRAY_BUFFER, 0, data_size_in_bytes, data_indices);
+
+GLint size = 0;
+{%glGetBufferParameteriv}(GL_ELEMENT_ARRAY_BUFFER, GL_BUFFER_SIZE, &size);
+if(data_size_in_bytes != size)
+{
+	{%glDeleteBuffers}(1, &index_buffer);
+	// Log the error
+	return;
+}
+
+// Success
+
diff --git a/html/examples/vertex_array.htm → html/examples/vertexarray_draw.htm b/html/examples/vertex_array.htm → html/examples/vertexarray_draw.htm
@@ -1,17 +1,16 @@
 {%glEnableVertexAttribArray}(texcoord_attrib_index); // Attribute indexes were received from calls to {%glGetAttribLocation}, or passed into {%glBindAttribLocation}.
-{%glVertexAttribPointer}(texcoord_attrib_index, 2, GL_FLOAT, false, 0, texcoords_data); // texcoords_data is a float*, 2 per vertex, representing UV coordinates.
-
 {%glEnableVertexAttribArray}(normal_attrib_index);
-{%glVertexAttribPointer}(normal_attrib_index, 3, GL_FLOAT, false, 0, normals_data); // normals_data is a float*, 3 per vertex, representing normal vectors.
-
 {%glEnableVertexAttribArray}(color_attrib_index);
-{%glVertexAttribPointer}(color_attrib_index, 3, GL_UNSIGNED_BYTE, true, sizeof(unsigned char)*3, colors_data); // colors_data is a unsigned char*, 3 per vertex, representing the color of each vertex.
-
 {%glEnableVertexAttribArray}(position_attrib_index);
+
+{%glVertexAttribPointer}(texcoord_attrib_index, 2, GL_FLOAT, false, 0, texcoords_data); // texcoords_data is a float*, 2 per vertex, representing UV coordinates.
+{%glVertexAttribPointer}(normal_attrib_index, 3, GL_FLOAT, false, 0, normals_data); // normals_data is a float*, 3 per vertex, representing normal vectors.
+{%glVertexAttribPointer}(color_attrib_index, 3, GL_UNSIGNED_BYTE, true, sizeof(unsigned char)*3, colors_data); // colors_data is a unsigned char*, 3 per vertex, representing the color of each vertex.
 {%glVertexAttribPointer}(position_attrib_index, 3, GL_FLOAT, false, 0, vertex_data); // vertex_data is a float*, 3 per vertex, representing the position of each vertex
+
 {%glDrawArrays}(GL_TRIANGLES, 0, vertex_data);
-{%glDisableVertexAttribArray}(position_attrib_index);
 
+{%glDisableVertexAttribArray}(position_attrib_index);
 {%glDisableVertexAttribArray}(texcoord_attrib_index);
 {%glDisableVertexAttribArray}(normal_attrib_index);
 {%glDisableVertexAttribArray}(color_attrib_index);
diff --git a/html/examples/vertexarray_draw_indexed.htm b/html/examples/vertexarray_draw_indexed.htm
@@ -0,0 +1,15 @@
+{%glEnableVertexAttribArray}(texcoord_attrib_index); // Attribute indexes were received from calls to {%glGetAttribLocation}, or passed into {%glBindAttribLocation}.
+{%glEnableVertexAttribArray}(normal_attrib_index);
+{%glEnableVertexAttribArray}(position_attrib_index);
+
+{%glVertexAttribPointer}(texcoord_attrib_index, 2, GL_FLOAT, false, 0, texcoords_data); // texcoords_data is a float*, 2 per vertex, representing UV coordinates.
+{%glVertexAttribPointer}(normal_attrib_index, 3, GL_FLOAT, false, 0, normals_data); // normals_data is a float*, 3 per vertex, representing normal vectors.
+{%glVertexAttribPointer}(position_attrib_index, 3, GL_FLOAT, false, 0, vertex_data); // vertex_data is a float*, 3 per vertex, representing the position of each vertex
+
+// num_vertices is the number of verts in your vertex_data.
+// index_data is an array of unsigned int offsets into vertex_data.
+{%glDrawElements}(GL_TRIANGLES, num_vertices, GL_UNSIGNED_INT, index_data);
+
+{%glDisableVertexAttribArray}(position_attrib_index);
+{%glDisableVertexAttribArray}(texcoord_attrib_index);
+{%glDisableVertexAttribArray}(normal_attrib_index);
diff --git a/opengl.py b/opengl.py
@@ -15,9 +15,25 @@
 example_functions = {}
 
 examples = {
-  'vertex_array': {
-    'description': 'Render a mesh with glDrawArrays using texture UV, normal, and color vertex attributes.',
-    'commands': [ 'glEnableVertexAttribArray', 'glVertexAttribPointer', 'glDrawArrays' ],
+  'vertexarray_draw': {
+    'description': 'Render a vertex array (not loaded into OpenGL) using texture UV, color, and normal vertex attributes.',
+    'commands': [ 'glDrawArrays' ],
+  },
+  'vertexarray_draw_indexed': {
+    'description': 'Render an indexed vertex array (not loaded into OpenGL) using texture UV and normal vertex attributes.',
+    'commands': [ 'glVertexAttribPointer', 'glDrawElements' ],
+  },
+  'vbo_load': {
+    'description': 'Load a vertex buffer into OpenGL for later rendering.',
+    'commands': [ 'glGenBuffers', 'glBindBuffer', 'glBufferData', 'glBufferSubData', 'glGetBufferParameteriv', 'glDeleteBuffers' ],
+  },
+  'vbo_load_index': {
+    'description': 'Load an index buffer into OpenGL for later rendering.',
+    'commands': [ 'glGenBuffers', 'glBindBuffer', 'glBufferData', 'glBufferSubData', 'glGetBufferParameteriv', 'glDeleteBuffers' ],
+  },
+  'vbo_draw_indexed': {
+    'description': 'Render an indexed buffer object using texture UV and normal vertex attributes.',
+    'commands': [ 'glBindBuffer', 'glEnableVertexAttribArray', 'glVertexAttribPointer', 'glDrawElements' ],
   },
   'shader_compile': {
     'description': 'Compile a program from a vertex shader and a fragment shader.',