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Switch OpenGL 2.1 backend to use vertex arrays

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This replaces the glBegin/glEnd stuff. Even though vertex arrays
aren't removed from newer OpenGL versions like glBegin/glEnd are,
they *are* deprecated, so I want to switch to VBOs eventually.
This commit is contained in:
Clownacy 2019-07-29 18:11:46 +00:00
parent 0b874153d4
commit 03b33adb70
1 changed files with 144 additions and 41 deletions
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185
src/Backends/Rendering/OpenGL2.cpp
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@ -29,6 +29,9 @@ static SDL_Window *window;
static SDL_GLContext context;
static GLuint colour_key_program_id;
static GLuint framebuffer_id;
static GLfloat vertex_buffer[4][2];
static GLfloat texture_coordinate_buffer[4][2];
static GLfloat colour_buffer[4][3];
static Backend_Surface framebuffer_surface;
@ -110,11 +113,17 @@ BOOL Backend_Init(SDL_Window *p_window)
if (!GLEW_EXT_framebuffer_object)
return FALSE;
glEnable(GL_TEXTURE_2D);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glEnableClientState(GL_TEXTURE_COORD_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, vertex_buffer);
glTexCoordPointer(2, GL_FLOAT, 0, texture_coordinate_buffer);
glColorPointer(3, GL_FLOAT, 0, colour_buffer);
glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
@ -172,17 +181,38 @@ void Backend_DrawScreen(void)
glBindTexture(GL_TEXTURE_2D, framebuffer_surface.texture_id);
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f(0.0f, 1.0f);
glVertex2f(-1.0f, -1.0f);
glTexCoord2f(1.0f, 1.0f);
glVertex2f(1.0f, -1.0f);
glTexCoord2f(1.0f, 0.0f);
glVertex2f(1.0f, 1.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex2f(-1.0f, 1.0f);
glEnd();
colour_buffer[0][0] = 1.0f;
colour_buffer[0][1] = 1.0f;
colour_buffer[0][2] = 1.0f;
colour_buffer[1][0] = colour_buffer[0][0];
colour_buffer[1][1] = colour_buffer[0][1];
colour_buffer[1][2] = colour_buffer[0][2];
colour_buffer[2][0] = colour_buffer[0][0];
colour_buffer[2][1] = colour_buffer[0][1];
colour_buffer[2][2] = colour_buffer[0][2];
colour_buffer[3][0] = colour_buffer[0][0];
colour_buffer[3][1] = colour_buffer[0][1];
colour_buffer[3][2] = colour_buffer[0][2];
texture_coordinate_buffer[0][0] = 0.0f;
texture_coordinate_buffer[0][1] = 1.0f;
texture_coordinate_buffer[1][0] = 1.0f;
texture_coordinate_buffer[1][1] = 1.0f;
texture_coordinate_buffer[2][0] = 1.0f;
texture_coordinate_buffer[2][1] = 0.0f;
texture_coordinate_buffer[3][0] = 0.0f;
texture_coordinate_buffer[3][1] = 0.0f;
vertex_buffer[0][0] = -1.0f;
vertex_buffer[0][1] = -1.0f;
vertex_buffer[1][0] = 1.0f;
vertex_buffer[1][1] = -1.0f;
vertex_buffer[2][0] = 1.0f;
vertex_buffer[2][1] = 1.0f;
vertex_buffer[3][0] = -1.0f;
vertex_buffer[3][1] = 1.0f;
glDrawArrays(GL_QUADS, 0, 4);
glPopMatrix();
@ -254,17 +284,48 @@ static void BlitCommon(Backend_Surface *source_surface, const RECT *rect, long x
glBindTexture(GL_TEXTURE_2D, source_surface->texture_id);
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f);
glTexCoord2f((GLfloat)rect->left / (GLfloat)source_surface->width, (GLfloat)rect->top / (GLfloat)source_surface->height);
glVertex2f((GLfloat)x, (GLfloat)y);
glTexCoord2f((GLfloat)rect->right / (GLfloat)source_surface->width, (GLfloat)rect->top / (GLfloat)source_surface->height);
glVertex2f((GLfloat)x + (rect->right - rect->left), (GLfloat)y);
glTexCoord2f((GLfloat)rect->right / (GLfloat)source_surface->width, (GLfloat)rect->bottom / (GLfloat)source_surface->height);
glVertex2f((GLfloat)x + (rect->right - rect->left), (GLfloat)y + (rect->bottom - rect->top));
glTexCoord2f((GLfloat)rect->left / (GLfloat)source_surface->width, (GLfloat)rect->bottom / (GLfloat)source_surface->height);
glVertex2f((GLfloat)x, (GLfloat)y + (rect->bottom - rect->top));
glEnd();
const GLfloat texture_left = (GLfloat)rect->left / (GLfloat)source_surface->width;
const GLfloat texture_right = (GLfloat)rect->right / (GLfloat)source_surface->width;
const GLfloat texture_top = (GLfloat)rect->top / (GLfloat)source_surface->height;
const GLfloat texture_bottom = (GLfloat)rect->bottom / (GLfloat)source_surface->height;
const GLfloat vertex_left = (GLfloat)x;
const GLfloat vertex_right = (GLfloat)x + (rect->right - rect->left);
const GLfloat vertex_top = (GLfloat)y;
const GLfloat vertex_bottom = (GLfloat)y + (rect->bottom - rect->top);
colour_buffer[0][0] = 1.0f;
colour_buffer[0][1] = 1.0f;
colour_buffer[0][2] = 1.0f;
colour_buffer[1][0] = colour_buffer[0][0];
colour_buffer[1][1] = colour_buffer[0][1];
colour_buffer[1][2] = colour_buffer[0][2];
colour_buffer[2][0] = colour_buffer[0][0];
colour_buffer[2][1] = colour_buffer[0][1];
colour_buffer[2][2] = colour_buffer[0][2];
colour_buffer[3][0] = colour_buffer[0][0];
colour_buffer[3][1] = colour_buffer[0][1];
colour_buffer[3][2] = colour_buffer[0][2];
texture_coordinate_buffer[0][0] = texture_left;
texture_coordinate_buffer[0][1] = texture_top;
texture_coordinate_buffer[1][0] = texture_right;
texture_coordinate_buffer[1][1] = texture_top;
texture_coordinate_buffer[2][0] = texture_right;
texture_coordinate_buffer[2][1] = texture_bottom;
texture_coordinate_buffer[3][0] = texture_left;
texture_coordinate_buffer[3][1] = texture_bottom;
vertex_buffer[0][0] = vertex_left;
vertex_buffer[0][1] = vertex_top;
vertex_buffer[1][0] = vertex_right;
vertex_buffer[1][1] = vertex_top;
vertex_buffer[2][0] = vertex_right;
vertex_buffer[2][1] = vertex_bottom;
vertex_buffer[3][0] = vertex_left;
vertex_buffer[3][1] = vertex_bottom;
glDrawArrays(GL_QUADS, 0, 4);
}
void Backend_Blit(Backend_Surface *source_surface, const RECT *rect, Backend_Surface *destination_surface, long x, long y, BOOL colour_key)
@ -300,13 +361,29 @@ static void ColourFillCommon(const RECT *rect, unsigned char red, unsigned char
// Use blank default texture, for a solid colour-fill
glBindTexture(GL_TEXTURE_2D, 0);
glBegin(GL_QUADS);
glColor3f(red / 255.0f, green / 255.0f, blue / 255.0f);
glVertex2f((GLfloat)rect->left, (GLfloat)rect->top);
glVertex2f((GLfloat)rect->right, (GLfloat)rect->top);
glVertex2f((GLfloat)rect->right, (GLfloat)rect->bottom);
glVertex2f((GLfloat)rect->left, (GLfloat)rect->bottom);
glEnd();
colour_buffer[0][0] = red / 255.0f;
colour_buffer[0][1] = green / 255.0f;
colour_buffer[0][2] = blue / 255.0f;
colour_buffer[1][0] = colour_buffer[0][0];
colour_buffer[1][1] = colour_buffer[0][1];
colour_buffer[1][2] = colour_buffer[0][2];
colour_buffer[2][0] = colour_buffer[0][0];
colour_buffer[2][1] = colour_buffer[0][1];
colour_buffer[2][2] = colour_buffer[0][2];
colour_buffer[3][0] = colour_buffer[0][0];
colour_buffer[3][1] = colour_buffer[0][1];
colour_buffer[3][2] = colour_buffer[0][2];
vertex_buffer[0][0] = (GLfloat)rect->left;
vertex_buffer[0][1] = (GLfloat)rect->top;
vertex_buffer[1][0] = (GLfloat)rect->right;
vertex_buffer[1][1] = (GLfloat)rect->top;
vertex_buffer[2][0] = (GLfloat)rect->right;
vertex_buffer[2][1] = (GLfloat)rect->bottom;
vertex_buffer[3][0] = (GLfloat)rect->left;
vertex_buffer[3][1] = (GLfloat)rect->bottom;
glDrawArrays(GL_QUADS, 0, 4);
}
void Backend_ColourFill(Backend_Surface *surface, const RECT *rect, unsigned char red, unsigned char green, unsigned char blue)
@ -424,17 +501,43 @@ static void DrawGlyphCommon(Backend_Glyph *glyph, long x, long y, const unsigned
glBindTexture(GL_TEXTURE_2D, glyph->texture_id);
glBegin(GL_QUADS);
glColor3f(colours[0] / 255.0f, colours[1] / 255.0f, colours[2] / 255.0f);
glTexCoord2f(0.0f, 0.0f);
glVertex2f((GLfloat)x, (GLfloat)y);
glTexCoord2f(1.0f, 0.0f);
glVertex2f((GLfloat)x + glyph->width, (GLfloat)y);
glTexCoord2f(1.0f, 1.0f);
glVertex2f((GLfloat)x + glyph->width, (GLfloat)y + glyph->height);
glTexCoord2f(0.0f, 1.0f);
glVertex2f((GLfloat)x, (GLfloat)y + glyph->height);
glEnd();
const GLfloat vertex_left = (GLfloat)x;
const GLfloat vertex_right = (GLfloat)x + glyph->width;
const GLfloat vertex_top = (GLfloat)y;
const GLfloat vertex_bottom = (GLfloat)y + glyph->height;
colour_buffer[0][0] = colours[0] / 255.0f;
colour_buffer[0][1] = colours[1] / 255.0f;
colour_buffer[0][2] = colours[2] / 255.0f;
colour_buffer[1][0] = colour_buffer[0][0];
colour_buffer[1][1] = colour_buffer[0][1];
colour_buffer[1][2] = colour_buffer[0][2];
colour_buffer[2][0] = colour_buffer[0][0];
colour_buffer[2][1] = colour_buffer[0][1];
colour_buffer[2][2] = colour_buffer[0][2];
colour_buffer[3][0] = colour_buffer[0][0];
colour_buffer[3][1] = colour_buffer[0][1];
colour_buffer[3][2] = colour_buffer[0][2];
texture_coordinate_buffer[0][0] = 0.0f;
texture_coordinate_buffer[0][1] = 0.0f;
texture_coordinate_buffer[1][0] = 1.0f;
texture_coordinate_buffer[1][1] = 0.0f;
texture_coordinate_buffer[2][0] = 1.0f;
texture_coordinate_buffer[2][1] = 1.0f;
texture_coordinate_buffer[3][0] = 0.0f;
texture_coordinate_buffer[3][1] = 1.0f;
vertex_buffer[0][0] = vertex_left;
vertex_buffer[0][1] = vertex_top;
vertex_buffer[1][0] = vertex_right;
vertex_buffer[1][1] = vertex_top;
vertex_buffer[2][0] = vertex_right;
vertex_buffer[2][1] = vertex_bottom;
vertex_buffer[3][0] = vertex_left;
vertex_buffer[3][1] = vertex_bottom;
glDrawArrays(GL_QUADS, 0, 4);
}
void Backend_DrawGlyph(Backend_Surface *surface, Backend_Glyph *glyph, long x, long y, const unsigned char *colours)