1 files changed, 189 insertions, 0 deletions
diff --git a/src/tex.c b/src/tex.c
new file mode 100644
index 0000000..b8254e1
--- /dev/null
+++ b/src/tex.c
@@ -0,0 +1,189 @@
+/*
+ *  Copyright (C) 2020 - Vito Caputo - <vcaputo@pengaru.com>
+ *
+ *  This program is free software: you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 3 as published
+ *  by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+
+#include "glad.h"
+#include "m4f.h"
+#include "macros.h"
+#include "shader.h"
+#include "tex.h"
+
+typedef struct tex_t {
+	unsigned	tex;
+	unsigned	refcnt;
+} tex_t;
+
+static unsigned	vbo, tcbo;
+static shader_t	*tex_shader;
+
+static const float	vertices[] = {
+	+1.f, +1.f, 0.f,
+	+1.f, -1.f, 0.f,
+	-1.f, +1.f, 0.f,
+	+1.f, -1.f, 0.f,
+	-1.f, -1.f, 0.f,
+	-1.f, +1.f, 0.f,
+};
+
+static const float	texcoords[] = {
+	1.f, 0.f,
+	1.f, 1.f,
+	0.f, 0.f,
+	1.f, 1.f,
+	0.f, 1.f,
+	0.f, 0.f,
+};
+
+
+static const char	*tex_vs = ""
+	"#version 120\n"
+
+	"uniform mat4	model_x;"
+
+	"attribute vec3	vertex;"
+	"attribute vec2	texcoord;"
+
+	"void main()"
+	"{"
+	"	gl_TexCoord[0].xy = texcoord;"
+	"	gl_Position = model_x * vec4(vertex, 1.f);"
+	"}"
+"";
+
+
+static const char	*tex_fs = ""
+	"#version 120\n"
+
+	"uniform sampler2D	tex0;"
+	"uniform float		alpha;"
+
+	"void main()"
+	"{"
+	"	gl_FragColor = texture2D(tex0, gl_TexCoord[0].st);"
+	"	gl_FragColor.a *= alpha;"
+	"}"
+"";
+
+
+/* Render simply renders a texd texture onto the screen */
+void tex_render(tex_t *tex, float alpha, m4f_t *model_x)
+{
+	int		*uniforms, *attributes;
+
+	assert(tex);
+	assert(model_x);
+
+	shader_use(tex_shader, NULL, &uniforms, NULL, &attributes);
+
+	glBindBuffer(GL_ARRAY_BUFFER, vbo);
+	glVertexAttribPointer(attributes[0], 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+	glEnableVertexAttribArray(attributes[0]);
+
+	glBindBuffer(GL_ARRAY_BUFFER, tcbo);
+	glVertexAttribPointer(attributes[1], 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), (void *)0);
+	glEnableVertexAttribArray(attributes[1]);
+
+	glBindTexture(GL_TEXTURE_2D, tex->tex);
+
+	glEnable(GL_BLEND);
+	glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+	glUniform1f(uniforms[0], alpha);
+	glUniformMatrix4fv(uniforms[1], 1, GL_FALSE, &model_x->m[0][0]);
+
+	glDrawArrays(GL_TRIANGLES, 0, 6);
+
+	glBindTexture(GL_TEXTURE_2D, 0);
+	glUseProgram(0);
+	glBindBuffer(GL_ARRAY_BUFFER, 0);
+}
+
+
+tex_t * tex_new(int width, int height, const unsigned char *buf)
+{
+	tex_t	*tex;
+
+	assert(buf);
+
+	if (!vbo) {
+		/* common to all tex instances */
+		tex_shader = shader_pair_new(tex_vs, tex_fs,
+					2,
+					(const char *[]) {
+						"alpha",
+						"model_x",
+					},
+					2,
+					(const char *[]) {
+						"vertex",
+						"texcoord",
+					});
+
+		glGenBuffers(1, &vbo);
+		glBindBuffer(GL_ARRAY_BUFFER, vbo);
+		glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+
+		glGenBuffers(1, &tcbo);
+		glBindBuffer(GL_ARRAY_BUFFER, tcbo);
+		glBufferData(GL_ARRAY_BUFFER, sizeof(texcoords), texcoords, GL_STATIC_DRAW);
+
+		glBindBuffer(GL_ARRAY_BUFFER, 0);
+	}
+
+	tex = calloc(1, sizeof(tex_t));
+	fatal_if(!tex, "Unable to allocate tex_t");
+
+	glGenTextures(1, &tex->tex);
+	glBindTexture(GL_TEXTURE_2D, tex->tex);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, buf);
+	glBindTexture(GL_TEXTURE_2D, 0);
+
+	tex->refcnt = 1;
+
+	return tex;
+}
+
+
+tex_t * tex_ref(tex_t *tex)
+{
+	assert(tex);
+
+	tex->refcnt++;
+
+	return tex;
+}
+
+
+tex_t * tex_free(tex_t *tex)
+{
+	if (!tex)
+		return NULL;
+
+	assert(tex->refcnt > 0);
+
+	tex->refcnt--;
+	if (!tex->refcnt) {
+		glDeleteTextures(1, &tex->tex);
+		free(tex);
+	}
+
+	return NULL;
+}