src/gl_minimal.c: Make GL example really fancy now

Show GL is working for real with some sinnyness!!!

Signed-off-by: Edward O'Callaghan <funfunctor@folklore1984.net>

1 files changed, 81 insertions, 0 deletions

diff --git a/src/gl_minimal.c b/src/gl_minimal.c
index 3898230..0e9d418 100644
--- a/src/gl_minimal.c
+++ b/src/gl_minimal.c
@@ -1,6 +1,7 @@
 #include <epoxy/gl.h>
 #include <epoxy/glx.h>
 
+#include <assert.h>
 #include <unistd.h>
 #include <stdio.h>
 
@@ -42,6 +43,86 @@ void run_gl_example(struct display * d)
 		sleep(3);
 	}
 
+	const GLfloat vertices[] = {
+	   0.0f,  0.5f,  0.0f,
+	   0.5f, -0.5f,  0.0f,
+	  -0.5f, -0.5f,  0.0f
+	};
+
+	GLuint vao, vbo;
+	glGenVertexArrays(1, &vao);
+	glGenBuffers(1, &vbo);
+
+	glBindVertexArray(vao);
+
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
+	glEnableVertexAttribArray(0);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+	glBindVertexArray(0);
+
+	const char* vertex_shader =
+	"#version 130\n"
+	"in vec3 position;"
+	"void main() {"
+	"  gl_Position = vec4(position.x, position.y, position.z, 1.0);"
+	"}";
+
+	const char* fragment_shader =
+	"#version 130\n"
+	"out vec4 frag_colour;"
+	"void main() {"
+	"  frag_colour = vec4(1.0f, 0.5f, 0.2f, 1.0f);"
+	"}";
+
+	GLint success;
+	GLchar infoLog[512];
+
+	GLuint vs = glCreateShader(GL_VERTEX_SHADER);
+	glShaderSource(vs, 1, &vertex_shader, NULL);
+	glCompileShader(vs);
+	glGetShaderiv(vs, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		glGetShaderInfoLog(vs, 512, NULL, infoLog);
+		printf("%s\n", infoLog);
+		assert(0);
+	}
+
+	GLuint fs = glCreateShader(GL_FRAGMENT_SHADER);
+	glShaderSource(fs, 1, &fragment_shader, NULL);
+	glCompileShader(fs);
+	glGetShaderiv(fs, GL_COMPILE_STATUS, &success);
+	if (!success) {
+		glGetShaderInfoLog(fs, 512, NULL, infoLog);
+		printf("%s\n", infoLog);
+		assert(0);
+	}
+
+	GLuint shader_programme = glCreateProgram();
+	glAttachShader(shader_programme, fs);
+	glAttachShader(shader_programme, vs);
+	glLinkProgram(shader_programme);
+	glDeleteShader(vs);
+	glDeleteShader(fs);
+
+	glClearColor(0.3,0.3,0.3, 1.0);
+	// wipe the drawing surface clear
+	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+	glBindVertexArray(vao);
+	glUseProgram(shader_programme);
+	// draw points 0-3 from the currently bound VAO with current in-use shader
+	glDrawArrays(GL_TRIANGLES, 0, 3);
+	glBindVertexArray(0);
+
+	glFlush();
+	sleep(3);
+
+	glDeleteVertexArrays(1, &vao);
+	glDeleteBuffers(1, &vbo);
+
 //	sleep(2);
 //	eglSwapBuffers(d->egl.display, d->egl.surface);
 //	sleep(2);